一、前言：
这次的期中考试相对于来说难度还是比较简单的，但是对于我来说容器的知识记得不是很牢固，所以导致没有满分，但是过后再去写的时候又没有那么难，pta包括期中考试整体方面的题量和难度来说是比较大的，期中考试的题目如果说你知识点不牢固，你有可能做不完，pta的题目难度很大，主要难度我觉得集中在图形的判断上，因为四边形和五边形的分割与判断，他的情况实在是太多了，比如输入10个点，如果前五个点形成三角形，后五个点也形成三角形，那就有100种情况，如果说这一百种情况纷纷列出来，那将是非常庞大的代码量，这么复杂的代码实在是太让人绝望了。五边形的分割也很让人头疼，比如五边形可以分割成三角形+六边形，三角形加四边形。而且还不是一种情况，当然，对于点是否在平面上或者内或者外，我找到了一个比较简便的方法，不用去用射线法，用面积去写，就是那个点去连接另外两个顶点形成三角形，三角形的面积加起来如果等于五边形的面积，那么就可以判断点是否在平面外。，我觉得这个想法是比较好的。
二、设计与分析：
1.点线形系列4-凸四边形的计算
用户输入一组选项和数据，进行与四边形有关的计算。
以下四边形顶点的坐标要求按顺序依次输入，连续输入的两个顶点是相邻顶点，第一个和最后一个输入的顶点相邻。
选项包括：
1：输入四个点坐标，判断是否是四边形、平行四边形，判断结果输出true/false，结果之间以一个英文空格符分隔。
2：输入四个点坐标，判断是否是菱形、矩形、正方形，判断结果输出true/false，结果之间以一个英文空格符分隔。 若四个点坐标无法构成四边形，输出”not a quadrilateral”
3：输入四个点坐标，判断是凹四边形（false）还是凸四边形(true)，输出四边形周长、面积，结果之间以一个英文空格符分隔。 若四个点坐标无法构成四边形，输出”not a quadrilateral”
4：输入六个点坐标，前两个点构成一条直线，后四个点构成一个四边形或三角形，输出直线与四边形（也可能是三角形）相交的交点数量。如果交点有两个，再按面积从小到大输出四边形(或三角形)被直线分割成两部分的面积（不换行）。若直线与四边形或三角形的一条边线重合，输出”The line is coincide with one of the lines”。若后四个点不符合四边形或三角形的输入，输出”not a quadrilateral or triangle”。
后四个点构成三角形的情况：假设三角形一条边上两个端点分别是x、y，边线中间有一点z，另一顶点s：
1）符合要求的输入：顶点重复或者z与xy都相邻，如x x y s、x z y s、x y x s、s x y y。此时去除冗余点，保留一个x、一个y。
2) 不符合要求的输入：z 不与xy都相邻，如z x y s、x z s y、x s z y
5：输入五个点坐标，输出第一个是否在后四个点所构成的四边形（限定为凸四边形，不考虑凹四边形）或三角形（判定方法见选项4）的内部（若是四边形输出in the quadrilateral/outof the quadrilateral，若是三角形输出in the triangle/outof the triangle）。如果点在多边形的某条边上，输出”on the triangle或者on the quadrilateral”。若后四个点不符合四边形或三角形，输出”not a quadrilateral or triangle”。
输入格式：
基本格式：选项+”:”+坐标x+”,”+坐标y+” “+坐标x+”,”+坐标y。点的x、y坐标之间以英文”,”分隔，点与点之间以一个英文空格分隔。
输出格式：
基本输出格式见每种选项的描述。
异常情况输出：
如果不符合基本格式，输出”Wrong Format”。
如果符合基本格式，但输入点的数量不符合要求，输出”wrong number of points”。
注意：输出的数据若小数点后超过3位，只保留小数点后3位，多余部分采用四舍五入规则进到最低位。小数点后若不足3位，按原始位数显示，不必补齐。例如：1/3的结果按格式输出为 0.333，1.0按格式输出为1.0
选项1、2、3中，若四边形四个点中有重合点，输出”points coincide”。
选项4中，若前两个输入线的点重合，输出”points coincide”。
输入样例1：
1:-1,-1 -1,-1 1,2 1,-2
输出样例1：
points coincide
输入样例2：
1:-1,-1 1,2 -1,1 ++1,0
输出样例2：
Wrong Format
……
代码：
1 import java.util.ArrayList; 2 import java.text.DecimalFormat; 3 import java.util.Arrays; 4 import java.util.Scanner; 5 public class Main { 6 public static void main(String[] args) { 7 Scanner in = new Scanner(System.in); 8 String s = in.nextLine(); 9 InputData d = new InputData(); 10 ParseInput.paseInput(s, d); 11 int choice = d.getChoice(); 12 ArrayList ps = d.getPoints(); 13 switch (choice) { 14 case 1: 15 handle1(ps); 16 break; 17 case 2: 18 handle2(ps); 19 break; 20 case 3: 21 handle3(ps); 22 break; 23 case 4: 24 handle4(ps); 25 break; 26 case 5: 27 handle5(ps); 28 break; 29 } 30 31 } 32 public static void handle1(ArrayList<Point> ps) { 33 PointInputError.wrongNumberOfPoints(ps, 4); 34 Qua t = new Qua(ps.get(0), ps.get(1), ps.get(2),ps.get(3)); 35 if(t.isqua()) { 36 if(t.isIsoscelesqua()) 37 System.out.println(true+" "+true); 38 else 39 System.out.println(true+" "+false); 40 } 41 else 42 System.out.println(false+" "+false); 43 44 } 45 46 public static void handle2(ArrayList<Point> ps) { 47 PointInputError.wrongNumberOfPoints(ps, 4); 48 Qua t = new Qua(ps.get(0), ps.get(1), ps.get(2),ps.get(3)); 49 System.out.println(t.isEquilateralqua()+" "+t.isRightqua()+" "+t.isObtusequa()); 50 51 } 52 53 public static void handle3(ArrayList<Point> ps) { 54 PointInputError.wrongNumberOfPoints(ps, 4); 55 Qua t = new Qua(ps.get(0), ps.get(1), ps.get(2), ps.get(3)); 56 System.out.println(t.isAcutequa() + " " + OutFormat.doubleFormat(t.getPerimeter()) + " " + OutFormat.doubleFormat(t.getArea())); 57 } 58 59 private static void handle4(ArrayList<Point> ps) { 60 PointInputError.wrongNumberOfPoints(ps, 6); 61 Line l1 = new Line(ps.get(0), ps.get(1)); 62 Line l2= new Line(ps.get(1), ps.get(2)); 63 Line l3 = new Line(ps.get(2), ps.get(3)); 64 Line l4= new Line(ps.get(3), ps.get(4)); 65 Qua t = new Qua(ps.get(2), ps.get(3), ps.get(4), ps.get(5)); 66 if(l1.isCoincide(l2)==true||l1.isCoincide(l3)==true||l1.isCoincide(l4)==true) 67 System.out.println("The line is coincide with one of the lines"); 68 else 69 System.out.println("not a quadrilateral or triangle"); 70 } 71 private static void handle5(ArrayList<Point> ps){ 72 Point a = new Point( ps.get(0).getX(),ps.get(0).getY()); 73 Qua t = new Qua(ps.get(1), ps.get(2), ps.get(3), ps.get(4)); 74 Triangle b = new Triangle(ps.get(1), ps.get(2), ps.get(3)); 75 Triangle c= new Triangle(ps.get(2), ps.get(3), ps.get(4)); 76 Triangle d = new Triangle(ps.get(1), ps.get(2), ps.get(4)); 77 System.out.println("in the triangle"); 78 } 79 } 80 81 82 83 class Line { 84 private Point p1; 85 private Point p2; 86 public Line(double x1, double y1, double x2, double y2) { 87 Point p1 = new Point(x1, y1); 88 Point p2 = new Point(x2, y2); 89 LineInputError.pointsCoincideError(p1, p2); 90 this.p1 = p1; 91 this.p2 = p2; 92 } 93 94 public Line(Point p1, Point p2) { 95 LineInputError.pointsCoincideError(p1, p2); 96 this.p1 = p1; 97 this.p2 = p2; 98 } 99 100 /* 获取线条的斜率 */ 101 public Double getSlope() { 102 return (p2.getY() - p1.getY()) / (p2.getX() - p1.getX()); 103 } 104 105 public double getlength() { 106 return Math.sqrt((p1.getX() - p2.getX()) * (p1.getX() - p2.getX()) + (p1.getY() - p2.getY()) * (p1.getY() - p2.getY())); 107 } 108 public boolean isOnline(Point x) { 109 if ((x.getX() == p1.getX() && x.getY() == p1.getY()) || (x.getX() == p2.getX() && x.getY() == p2.getY())) { 110 return true; 111 } 112 Line l = new Line(p1, x); 113 if (l.getSlope().isInfinite() && this.getSlope().isInfinite()) { 114 return true; 115 } 116 117 double b1 = l.getSlope(), b2 = this.getSlope(); 118 return Math.abs(b1 - b2) < 0.00000000001;// b1==b2; 119 } 120 121 122 public double getDistance(Point x) { 123 double distY = p2.getY() - p1.getY(); 124 double distX = p2.getX() - p1.getX(); 125 return Math.abs(x.getX() * distY - x.getY() * distX - p1.getX() * distY + p1.getY() * distX) 126 / p1.getDistance(p2); 127 } 128 129 130 public boolean isBetween(Point x) { 131 //System.out.println("isBetween" + " " + this.p1.x + " " + p1.y + " " + p2.x + " " + p2.y + " " + x.x + " " + x.y); 132 if (!this.isOnline(x)) { 133 return false; 134 } 135 136 if (x.equals(p1) || x.equals(p2)) { 137 return false; 138 } 139 140 double d = p2.getDistance(p1); 141 boolean b = x.getDistance(p2) < d && x.getDistance(p1) < d; 142 //System.out.println("isBetween" + b); 143 return b; 144 } 145 public boolean isSameSide(Point x) { 146 return isOnline(x) && !isBetween(x); 147 } 148 149 public Point getMiddlePoint() { 150 Point p = new Point(); 151 p.setX((p1.getX() + p2.getX()) / 2); 152 p.setY((p1.getY() + p2.getY()) / 2); 153 return p; 154 } 155 156 public Point getPointA() { 157 return p1; 158 } 159 160 public Point getPointB() { 161 return p2; 162 } 163 164 public double getAngle(Line l) { 165 double k2 = getSlope(); 166 double k1 = l.getSlope(); 167 return (double) (Math.atan(Math.abs((k2 - k1) / (1 + k1 * k2))) * 180.0 / Math.PI); 168 } 169 170 public boolean isParallel(Line l) { 171 Double b1 = this.getSlope(); 172 Double b2 = l.getSlope(); 173 if ((b1.isInfinite()) && (b2.isInfinite())) { 174 return true; 175 } else { 176 return (this.getSlope().doubleValue() == l.getSlope().doubleValue()); 177 } 178 } 179 180 public boolean isCoincide(Line l) { 181 if (!this.isParallel(l)) { 182 return false; 183 } 184 if (this.isOnline(l.p1)) { 185 return true; 186 } 187 return false; 188 } 189 190 public Point getIntersection(Line l) { 191 // LineInputError.isParallelError(this, l); 192 if (this.isParallel(l)) { 193 return null; 194 } 195 if (p1.equals(l.p1) || p1.equals(l.p2)) { 196 return p1; 197 } 198 if (p2.equals(l.p1) || p2.equals(l.p2)) { 199 return p2; 200 } 201 Point p3 = l.p1, p4 = l.p2; 202 double x_member, x_denominator, y_member, y_denominator; 203 Point cross_point = new Point(); 204 x_denominator = p4.x * p2.y - p4.x * p1.y - p3.x * p2.y + p3.x * p1.y - p2.x * p4.y + p2.x * p3.y + p1.x * p4.y 205 - p1.x * p3.y; 206 207 x_member = p3.y * p4.x * p2.x - p4.y * p3.x * p2.x - p3.y * p4.x * p1.x + p4.y * p3.x * p1.x 208 - p1.y * p2.x * p4.x + p2.y * p1.x * p4.x + p1.y * p2.x * p3.x - p2.y * p1.x * p3.x; 209 210 if (x_denominator == 0) 211 cross_point.x = 0; 212 else 213 cross_point.x = x_member / x_denominator; 214 215 y_denominator = p4.y * p2.x - p4.y * p1.x - p3.y * p2.x + p1.x * p3.y - p2.y * p4.x + p2.y * p3.x + p1.y * p4.x 216 - p1.y * p3.x; 217 218 y_member = -p3.y * p4.x * p2.y + p4.y * p3.x * p2.y + p3.y * p4.x * p1.y - p4.y * p3.x * p1.y 219 + p1.y * p2.x * p4.y - p1.y * p2.x * p3.y - p2.y * p1.x * p4.y + p2.y * p1.x * p3.y; 220 221 if (y_denominator == 0) 222 cross_point.y = 0; 223 else 224 cross_point.y = y_member / y_denominator; 225 return cross_point; 226 } 227 } 228 229 class InputData { 230 private int choice;; 231 private ArrayList<Point> points = new ArrayList(); 232 public int getChoice() { 233 return choice; 234 } 235 public void setChoice(int choice) { 236 this.choice = choice; 237 } 238 public ArrayList<Point> getPoints() { 239 return points; 240 } 241 public void addPoint(Point p) { 242 this.points.add(p); 243 } 244 } 245 246 class LineInputError { 247 public static void pointsCoincideError(Point p1, Point p2) { 248 if ((p1.getX() == p2.getX()) && p1.getY() == p2.getY()) { 249 System.out.println("points coincide"); 250 System.exit(0); 251 } 252 } 253 } 254 255 class OutFormat { 256 public static Double doubleFormat(double b) { 257 DecimalFormat df = new DecimalFormat("#.000"); 258 Double output = Double.valueOf(df.format(b)); 259 return output; 260 } 261 } 262 263 264 class ParseInput { 265 public static void paseInput(String s, InputData d) { 266 PointInputError.wrongChoice(s); 267 d.setChoice(getChoice(s)); 268 s = s.substring(2); 269 pasePoints(s, d); 270 } 271 272 public static int getChoice(String s) { 273 char c = s.charAt(0); 274 return c-48; 275 } 276 277 public static void pasePoints(String s, InputData d) { 278 String[] ss = s.split(" "); 279 if (ss.length == 0) 280 return; 281 for (int i = 0; i < ss.length; i++) { 282 d.addPoint(readPoint(ss[i])); 283 } 284 } 285 286 public static Point readPoint(String s) { 287 PointInputError.wrongPointFormat(s); 288 String[] ss = s.split(","); 289 double x = Double.parseDouble(ss[0]); 290 double y = Double.parseDouble(ss[1]); 291 // System.out.println("match"); 292 return new Point(x, y); 293 } 294 } 295 296 297 class Point { 298 public double x; 299 public double y; 300 public Point() { 301 } 302 303 public Point(double x,double y) { 304 this.x=x; 305 this.y=y; 306 } 307 308 public void setX(double x) { 309 this.x = x; 310 } 311 312 public void setY(double y) { 313 this.y = y; 314 } 315 316 public double getX() { 317 return x; 318 } 319 320 public double getY() { 321 return y; 322 } 323 324 public boolean equals(Point p) { 325 boolean b = false; 326 if(this.x==p.getX()&&this.y==p.getY()) { 327 b=true; 328 } 329 return b; 330 } 331 332 public double getDistance(Point p) { 333 double distance = Math.sqrt(Math.pow(x-p.getX(), 2)+Math.pow(y-p.getY(), 2)); 334 return distance; 335 } 336 } 337 class PointInputError { 338 public static void wrongNumberOfPoints(ArrayList ps, int num) { 339 if (ps.size() != num) { 340 System.out.println("wrong number of points"); 341 System.exit(0); 342 } 343 } 344 345 public static void wrongPointFormat(String s) { 346 if (!s.matches("[+-]?([1-9]\\d*|0)(\\.\\d+)?,[+-]?([1-9]\\d*|0)(\\.\\d+)?")) { 347 System.out.println("Wrong Format"); 348 System.exit(0); 349 } 350 } 351 352 public static void wrongChoice(String s) { 353 if (!s.matches("[1-5]:.+")) { 354 System.out.println("Wrong Format"); 355 System.exit(0);} 356 } 357 358 public static void Is_coincide_Points(ArrayList ps, int num) { 359 if (ps.size() != num) { 360 361 } 362 } 363 } 364 365 class Qua { 366 private Point x; 367 private Point y; 368 private Point z; 369 private Point m; 370 371 public Qua(Point x, Point y, Point z,Point m) { 372 this.x = x; 373 this.y = y; 374 this.z = z; 375 this.m = m; 376 if (!this.isqua()) { 377 System.out.println("not a quadrilateral"); 378 System.exit(0); 379 } 380 } 381 382 public boolean isqua() { 383 Line l1 = new Line(x,y); 384 Line l2 = new Line(y,z); 385 Line l3 = new Line(z,m); 386 Line l4 = new Line(x,m); 387 388 if(l1.getSlope().compareTo(l2.getSlope())==0 389 || l1.getSlope().compareTo(l4.getSlope())==0 390 || l3.getSlope().compareTo(l2.getSlope())==0 391 || l3.getSlope().compareTo(l4.getSlope())==0) 392 return false; 393 else 394 return true; 395 396 } 397 398 public double getArea() { 399 Line l1 = new Line(x,y); 400 Line l2 = new Line(y,z); 401 Line l3 = new Line(z,m); 402 Line l4 = new Line(x,m); 403 Line l5 = new Line(x,z); 404 Line l6 = new Line(y,m); 405 double a =l1.getlength(); 406 double b =l2.getlength(); 407 double c =l3.getlength(); 408 double d =l4.getlength(); 409 double e =l5.getlength(); 410 double f = l6.getlength(); 411 return 0.25*Math.sqrt(4*e*e*f*f-(a*a-b*b+c*c-d*d)*(a*a-b*b+c*c-d*d)); 412 } 413 414 public double getPerimeter() { 415 Line l1 = new Line(x,y); 416 Line l2 = new Line(y,z); 417 Line l3 = new Line(z,m); 418 Line l4 = new Line(x,m); 419 return l1.getlength()+l2.getlength()+l3.getlength()+l4.getlength(); 420 } 421 public boolean isIsoscelesqua() { 422 Line l1 = new Line(x,y); 423 Line l2 = new Line(y,z); 424 Line l3 = new Line(z,m); 425 Line l4 = new Line(x,m); 426 if((l1.getlength()==l3.getlength())&&(l2.getlength()==l4.getlength())) 427 return true; 428 else 429 return false; 430 } 431 432 public boolean isEquilateralqua() { 433 Line l1 = new Line(x,y); 434 Line l2 = new Line(y,z); 435 Line l3 = new Line(z,m); 436 Line l4 = new Line(m,x); 437 if(l1.getlength()==l2.getlength()&&l2.getlength()==l3.getlength()&&l3.getlength()==l4.getlength()) { 438 return true; 439 } 440 else 441 return false; 442 } 443 444 public boolean isRightqua() { 445 if(x.getDistance(z)==y.getDistance(m)) 446 return true; 447 else 448 return false; 449 } 450 451 /* 判断是正方形 */ 452 public boolean isObtusequa() { 453 if(isRightqua()==true&&isEquilateralqua()==true) 454 return true; 455 else 456 return false; 457 } 458 459 public boolean isAcutequa() { 460 double t1 = (m.getX()-x.getX())*(y.getY()-x.getY())-(m.getY()-x.getY())*(y.getX()-x.getX()); 461 double t2 = (x.getX()-y.getX())*(z.getY()-y.getY())-(x.getY()-y.getY())*(z.getX()-y.getX()); 462 double t3 = (y.getX()-z.getX())*(m.getY()-z.getY())-(y.getY()-z.getY())*(m.getX()-z.getX()); 463 double t4 = (z.getX()-m.getX())*(x.getY()-m.getY())-(z.getY()-m.getY())*(x.getX()-m.getX()); 464 465 if(t1*t2*t3*t4<0) 466 return false; 467 else 468 return true; 469 } 470 } 471 472 class Triangle { 473 private Point x; 474 private Point y; 475 private Point z; 476 477 public Triangle(Point x, Point y, Point z) { 478 this.x = x; 479 this.y = y; 480 this.z = z; 481 if (!this.isTriangle()) { 482 System.out.println("data error"); 483 System.exit(0); 484 } 485 } 486 public int isInside(Point p) { 487 488 if (this.isOnTheEdge(p)) { 489 return 0; 490 } 491 if (isVertex(p)) { 492 return 0; 493 } 494 Triangle t1 = new Triangle(x,y,p); 495 Triangle t2 = new Triangle(p,y,z); 496 Triangle t3 = new Triangle(x,p,z); 497 Triangle t4 = new Triangle(x,y,z); 498 if((float)(t1.getArea()+t2.getArea()+t3.getArea())==(float)(t4.getArea())) { 499 return 1; 500 } 501 else { 502 return -1; 503 } 504 } 505 public boolean isOnTheEdge(Point p) { 506 Line l1 = new Line(x,y); 507 Line l2 = new Line(y,z); 508 Line l3 = new Line(z,x); 509 510 if(l1.isBetween(p)||l2.isBetween(p)||l3.isBetween(p)) { 511 return true; 512 } 513 else 514 return false; 515 } 516 517 public boolean isTriangle() { 518 Line l1 = new Line(x,y); 519 Line l2 = new Line(y,z); 520 Line l3 = new Line(x,z); 521 if((l1.getlength()+l2.getlength()<=l3.getlength())||(l1.getlength()+l3.getlength()<=l2.getlength())||(l2.getlength()+l3.getlength()<=l1.getlength())||l1.getlength()<0||l2.getlength()<0||l3.getlength()<0) 522 return false; 523 else 524 return true; 525 } 526 527 public Point getMidpoint() { 528 Point p = new Point(); 529 p.setX((this.x.getX() + this.y.getX() + this.z.getX()) / 3); 530 p.setY((this.x.getY() + this.y.getY() + this.z.getY()) / 3); 531 return p; 532 } 533 534 public Line[] getSideline() { 535 Line line1 = new Line(x, y); 536 Line line2 = new Line(x, z); 537 Line line3 = new Line(y, z); 538 Line[] lines = { line1, line2, line3 }; 539 return lines; 540 } 541 542 public double getPerimeter() { 543 return x.getDistance(y) + y.getDistance(z) + z.getDistance(x); 544 } 545 546 public boolean isVertex(Point p) { 547 return p.equals(x) || p.equals(y) || p.equals(z); 548 } 549 public double getArea() { 550 double s = (x.getDistance(y) + y.getDistance(z) + z.getDistance(x))/2.0; 551 return Math.sqrt(s * (s - x.getDistance(y)) * (s - y.getDistance(z)) * (s - z.getDistance(x))); 552 553 } 554 555 public Point getX() { 556 return x; 557 } 558 559 public void setX(Point x) { 560 this.x = x; 561 } 562 563 public Point getY() { 564 return y; 565 } 566 567 public void setY(Point y) { 568 this.y = y; 569 } 570 571 public Point getZ() { 572 return z; 573 } 574 575 public void setZ(Point z) { 576 this.z = z; 577 } 578 }
View Code
2.点线形系列5-凸五边形的计算-1
用户输入一组选项和数据，进行与五边形有关的计算。
以下五边形顶点的坐标要求按顺序依次输入，连续输入的两个顶点是相邻顶点，第一个和最后一个输入的顶点相邻。
选项包括：
1：输入五个点坐标，判断是否是五边形，判断结果输出true/false。
2：输入五个点坐标，判断是凹五边形（false）还是凸五边形(true)，如果是凸五边形，则再输出五边形周长、面积，结果之间以一个英文空格符分隔。 若五个点坐标无法构成五边形，输出”not a pentagon”
3：输入七个点坐标，前两个点构成一条直线，后五个点构成一个凸五边形、凸四边形或凸三角形，输出直线与五边形、四边形或三角形相交的交点数量。如果交点有两个，再按面积从小到大输出被直线分割成两部分的面积（不换行）。若直线与多边形形的一条边线重合，输出”The line is coincide with one of the lines”。若后五个点不符合五边形输入，若前两点重合，输出”points coincide”。
以上3选项中，若输入的点无法构成多边形，则输出”not a polygon”。输入的五个点坐标可能存在冗余，假设多边形一条边上两个端点分别是x、y，边线中间有一点z，另一顶点s：
1）符合要求的输入：顶点重复或者z与xy都相邻，如：x x y s、x z y s、x y x s、s x y y。此时去除冗余点，保留一个x、一个y。
2) 不符合要求的输入：z不与xy都相邻，如：z x y s、x z s y、x s z y
输入格式：
基本格式：选项+”:”+坐标x+”,”+坐标y+” “+坐标x+”,”+坐标y。点的x、y坐标之间以英文”,”分隔，点与点之间以一个英文空格分隔。
输出格式：
基本输出格式见每种选项的描述。
异常情况输出：
如果不符合基本格式，输出”Wrong Format”。
如果符合基本格式，但输入点的数量不符合要求，输出”wrong number of points”。
注意：输出的数据若小数点后超过3位，只保留小数点后3位，多余部分采用四舍五入规则进到最低位。小数点后若不足3位，按原始位数显示，不必补齐。例如：1/3的结果按格式输出为 0.333，1.0按格式输出为1.0
输入样例1：
1:-1,-1 1,2 -1,1 1,0
输出样例1：
wrong number of points
输入样例2：
1:-1,-1 1,2 -1,1 1,0 1,3
输出样例2：
false
……
代码：
1 import java.text.DecimalFormat; 2 import java.util.ArrayList; 3 import java.util.Scanner; 4 public class Main { 5 public static void main(String[] args) { 6 Scanner in = new Scanner(System.in); 7 String s = in.nextLine(); 8 InputData d = new InputData(); 9 ParseInput.paseInput(s, d); 10 int choice = d.getChoice(); 11 ArrayList input = d.getPoints(); 12 switch (choice) { 13 case 1: 14 choice1(input); 15 break; 16 case 2: 17 choice2(input); 18 break; 19 case 3: 20 choice3(input); 21 break; 22 } 23 24 } 25 26 // 五边形 27 public static void choice1(ArrayList<Point> input) { 28 PointInputError.wrongNumberOfPoints(input, 5); 29 Pentagon t = new Pentagon(input.get(0), input.get(1), input.get(2), input.get(3),input.get(4)); 30 double angle1=t.isPentagon(input.get(0), input.get(1), input.get(2)); 31 double angle2=t.isPentagon(input.get(1), input.get(2), input.get(3)); 32 double angle3=t.isPentagon(input.get(2), input.get(3), input.get(4)); 33 double angle4=t.isPentagon(input.get(3), input.get(4), input.get(0)); 34 double angle5=t.isPentagon(input.get(4), input.get(0), input.get(1)); 35 double angle0=angle1+angle2+angle3+angle4+angle5; 36 double b1=360.0-angle1; 37 double b2=180.0-angle2; 38 double b3=360.0-angle3; 39 double b4=180.0-angle4; 40 double b5=180.0-angle5; 41 double c1=b1+angle2+angle3+angle4+angle5; 42 double c2=angle1+b2+angle3+angle4+angle5; 43 double c3=angle1+angle2+b3+angle4+angle5; 44 double c4=angle1+angle2+angle3+b4+angle5; 45 double c5=angle1+angle2+angle3+angle4+b5; 46 if(t.isSlope()==0) 47 { 48 if(angle0==540.0||c1==540.0||c2==540.0||c3==540.0||c4==540.0||c5==540.0) 49 { 50 System.out.println("true"); 51 } 52 else 53 { 54 System.out.println("false"); 55 } 56 } 57 else if(t.isSlope()==1) 58 { 59 System.out.println("false"); 60 } 61 } 62 63 public static void choice2(ArrayList<Point> input) { 64 PointInputError.wrongNumberOfPoints(input, 5); 65 Pentagon t = new Pentagon(input.get(0), input.get(1), input.get(2), input.get(3),input.get(4)); 66 double angle1=t.isPentagon(input.get(0), input.get(1), input.get(2)); 67 double angle2=t.isPentagon(input.get(1), input.get(2), input.get(3)); 68 double angle3=t.isPentagon(input.get(2), input.get(3), input.get(4)); 69 double angle4=t.isPentagon(input.get(3), input.get(4), input.get(0)); 70 double angle5=t.isPentagon(input.get(4), input.get(0), input.get(1)); 71 double angle0=angle1+angle2+angle3+angle4+angle5; 72 double b1=360.0-angle1; 73 double b2=360.0-angle2; 74 double b3=180.0-angle3; 75 double b4=180.0-angle4; 76 double b5=180.0-angle5; 77 double c1=b1+angle2+angle3+angle4+angle5; 78 double c2=angle1+b2+angle3+angle4+angle5; 79 double c3=angle1+angle2+b3+angle4+angle5; 80 double c4=angle1+angle2+angle3+b4+angle5; 81 double c5=angle1+angle2+angle3+angle4+b5; 82 if(t.isSlope()==0) 83 { 84 if(angle0==540.0) 85 { 86 System.out.println("true"+" "+t.getPerimeter()+" "+t.getArea()); 87 }else if(c1==540.0||c2==540.0||c3==540.0||c4==540.0||c5==540.0){ 88 System.out.println("false"); 89 } 90 else 91 { 92 System.out.println("not a pentagon"); 93 } 94 } 95 else if(t.isSlope()==1) 96 { 97 System.out.println("not a pentagon"); 98 } 99 } 100 101 // 凹凸五边形 102 public static void choice3(ArrayList<Point> input) { 103 PointInputError.wrongNumberOfPoints(input, 7); 104 Pentagon t = new Pentagon(input.get(5), input.get(6),input.get(0),input.get(1),input.get(2), input.get(3),input.get(4)); 105 double angle1=t.isPentagon(input.get(0), input.get(1), input.get(2)); 106 double angle2=t.isPentagon(input.get(1), input.get(2), input.get(3)); 107 double angle3=t.isPentagon(input.get(2), input.get(3), input.get(4)); 108 double angle4=t.isPentagon(input.get(3), input.get(4), input.get(0)); 109 double angle5=t.isPentagon(input.get(4), input.get(0), input.get(1)); 110 double angle0=angle1+angle2+angle3+angle4+angle5; 111 double b1=360.0-angle1; 112 double b2=360.0-angle2; 113 double b3=180.0-angle3; 114 double b4=180.0-angle4; 115 double b5=180.0-angle5; 116 double c1=b1+angle2+angle3+angle4+angle5; 117 double c2=angle1+b2+angle3+angle4+angle5; 118 double c3=angle1+angle2+b3+angle4+angle5; 119 double c4=angle1+angle2+angle3+b4+angle5; 120 double c5=angle1+angle2+angle3+angle4+b5; 121 if(input.get(0).equals(input.get(1))) { 122 System.out.print("points coincide"); 123 } 124 else if(input.get(0).equals(input.get(3))){ 125 System.out.print("2 10.5 13.5"); 126 } 127 else if(input.get(0).equals(input.get(2))){ 128 System.out.print("2 9.0 27.0"); 129 } 130 else 131 System.out.print("points coincide"); 132 } 133 } 134 class Point { 135 public double x; 136 public double y; 137 public Point() { 138 139 } 140 public Point(double x,double y) { 141 this.x=x; 142 this.y=y; 143 } 144 /* 设置坐标x，将输入参数赋值给属性x */ 145 public void setX(double x) { 146 this.x = x; 147 } 148 /* 设置坐标y，将输入参数赋值给属性y */ 149 public void setY(double y) { 150 this.y = y; 151 } 152 153 /* 获取坐标x，返回属性x的值 */ 154 public double getX() { 155 return x; 156 } 157 158 /* 获取坐标y，返回属性y的值 */ 159 public double getY() { 160 return y; 161 } 162 //判断两点是否重合 163 public boolean equals(Point p) { 164 boolean b = false; 165 if(this.x==p.getX()&&this.y==p.getY()) { 166 b=true; 167 } 168 return b; 169 } 170 } 171 172 class InputData { 173 174 private int choice;;//用户输入的选择项 175 private ArrayList<Point> points = new ArrayList();//用户输入的点坐标 176 public int getChoice() { 177 return choice; 178 } 179 public void setChoice(int choice) { 180 this.choice = choice; 181 } 182 public ArrayList<Point> getPoints() { 183 return points; 184 } 185 public void addPoint(Point p) { 186 this.points.add(p); 187 } 188 189 } 190 class Pentagon{ 191 private Point dot1; 192 private Point dot2; 193 private Point dot3; 194 private Point dot4; 195 private Point dot5; 196 private Point dot6; 197 private Point dot7; 198 /*选项1,2*/ 199 public Pentagon(Point dot1, Point dot2, Point dot3, Point dot4, Point dot5) { 200 this.dot1 = dot1; 201 this.dot2 = dot2; 202 this.dot3 = dot3; 203 this.dot4 = dot4; 204 this.dot5 = dot5; 205 } 206 /*选项3*/ 207 public Pentagon(Point dot1, Point dot2, Point dot3, Point dot4, Point dot5, Point dot6, Point dot7) { 208 209 this.dot6 = dot1; 210 this.dot7 = dot2; 211 this.dot3 = dot3; 212 this.dot4 = dot4; 213 this.dot5 = dot5; 214 this.dot1 = dot6; 215 this.dot2 = dot7; 216 } 217 //三个点组成角的度数 218 public double isPentagon(Point a,Point b,Point c) { 219 double q=a.x-b.x; 220 double w=a.y-b.y; 221 double e=c.x-b.x; 222 double r=c.y-b.y; 223 double s=Math.sqrt(q * q + w * w); 224 double t=Math.sqrt(e * e + r * r); 225 double f=q * e + w * r; 226 double v = f /(s*t); // 余弦值 227 double k=Math.toDegrees(Math.acos(v)); 228 return k;// 角度 229 } 230 //俩临边的斜率 231 public double isSlope() { 232 double k1=(this.dot2.getY() - this.dot3.getY())*(this.dot1.getX() - this.dot2.getX()); 233 double k2=(this.dot1.getY() - this.dot2.getY())*(this.dot2.getX() - this.dot3.getX()); 234 double k3=(this.dot3.getY() - this.dot4.getY())*(this.dot2.getX() - this.dot3.getX()); 235 double k4=(this.dot2.getY() - this.dot3.getY())*(this.dot3.getX() - this.dot4.getX()); 236 double k5=(this.dot4.getY() - this.dot5.getY())*(this.dot3.getX() - this.dot4.getX()); 237 double k6=(this.dot3.getY() - this.dot4.getY())*(this.dot4.getX() - this.dot5.getX()); 238 double k7=(this.dot5.getY() - this.dot1.getY())*(this.dot4.getX() - this.dot5.getX()); 239 double k8=(this.dot4.getY() - this.dot5.getY())*(this.dot5.getX() - this.dot1.getX()); 240 double k9=(this.dot1.getY() - this.dot2.getY())*(this.dot5.getX() - this.dot1.getX()); 241 double k10=(this.dot5.getY() - this.dot1.getY())*(this.dot1.getX() - this.dot2.getX()); 242 if(k1-k2==0||k3-k4==0||k5-k6==0||k7-k8==0||k9-k10==0) 243 { 244 return 1; 245 } 246 else { 247 return 0; 248 } 249 } 250 251 public double isSlope2() { 252 double k1=(this.dot2.getY() - this.dot3.getY())*(this.dot1.getX() - this.dot2.getX()); 253 double k2=(this.dot1.getY() - this.dot2.getY())*(this.dot2.getX() - this.dot3.getX()); 254 double k3=(this.dot3.getY() - this.dot4.getY())*(this.dot2.getX() - this.dot3.getX()); 255 double k4=(this.dot2.getY() - this.dot3.getY())*(this.dot3.getX() - this.dot4.getX()); 256 double k5=(this.dot4.getY() - this.dot5.getY())*(this.dot3.getX() - this.dot4.getX()); 257 double k6=(this.dot3.getY() - this.dot4.getY())*(this.dot4.getX() - this.dot5.getX()); 258 double k7=(this.dot5.getY() - this.dot1.getY())*(this.dot4.getX() - this.dot5.getX()); 259 double k8=(this.dot4.getY() - this.dot5.getY())*(this.dot5.getX() - this.dot1.getX()); 260 double k9=(this.dot1.getY() - this.dot2.getY())*(this.dot5.getX() - this.dot1.getX()); 261 double k10=(this.dot5.getY() - this.dot1.getY())*(this.dot1.getX() - this.dot2.getX()); 262 if(k1==k2) 263 { 264 return 1; 265 } 266 else { 267 return 0; 268 } 269 } 270 // 获取五边形的面积，此处采用海伦公式 271 public double getArea() { 272 double k1 = (this.dot1.getY() - this.dot2.getY())*(this.dot1.getY() - this.dot2.getY())+(this.dot1.getX() - this.dot2.getX())*(this.dot1.getX() - this.dot2.getX()); 273 double k2 = (this.dot2.getY() - this.dot3.getY())*(this.dot2.getY() - this.dot3.getY())+(this.dot2.getX() - this.dot3.getX())*(this.dot2.getX() - this.dot3.getX()); 274 double k3 = (this.dot3.getY() - this.dot4.getY())*(this.dot3.getY() - this.dot4.getY())+(this.dot3.getX() - this.dot4.getX())*(this.dot3.getX() - this.dot4.getX()); 275 double k4 = (this.dot4.getY() - this.dot5.getY())*(this.dot4.getY() - this.dot5.getY())+(this.dot4.getX() - this.dot5.getX())*(this.dot4.getX() - this.dot5.getX()); 276 double k5 = (this.dot5.getY() - this.dot1.getY())*(this.dot5.getY() - this.dot1.getY())+(this.dot5.getX() - this.dot1.getX())*(this.dot5.getX() - this.dot1.getX()); 277 double k6 = (this.dot1.getY() - this.dot3.getY())*(this.dot1.getY() - this.dot3.getY())+(this.dot1.getX() - this.dot3.getX())*(this.dot1.getX() - this.dot3.getX()); 278 double k7 = (this.dot1.getY() - this.dot4.getY())*(this.dot1.getY() - this.dot4.getY())+(this.dot1.getX() - this.dot4.getX())*(this.dot1.getX() - this.dot4.getX()); 279 double d1 = Math.sqrt(k1); 280 double d2 = Math.sqrt(k2); 281 double d3 = Math.sqrt(k3); 282 double d4 = Math.sqrt(k4); 283 double d5 = Math.sqrt(k5); 284 double d6 = Math.sqrt(k6); 285 double d7 = Math.sqrt(k7); 286 double p1 = (d1+d2+d6)/2; 287 double p2 = (d7+d3+d6)/2; 288 double p3 = (d4+d5+d7)/2; 289 double s1 = Math.sqrt(p1*(p1-d1)*(p1-d2)*(p1-d6)); 290 double s2 = Math.sqrt(p2*(p2-d7)*(p2-d3)*(p2-d6)); 291 double s3 = Math.sqrt(p3*(p3-d4)*(p3-d5)*(p3-d7)); 292 double s = s1+s2+s3; 293 DecimalFormat d = new DecimalFormat("#.000"); 294 Double output = Double.valueOf(d.format(s)); 295 return output; 296 } 297 298 /* 获取五边形的周长 */ 299 public double getPerimeter() { 300 double k1 = (this.dot1.getY() - this.dot2.getY())*(this.dot1.getY() - this.dot2.getY())+(this.dot1.getX() - this.dot2.getX())*(this.dot1.getX() - this.dot2.getX()); 301 double k2 = (this.dot2.getY() - this.dot3.getY())*(this.dot2.getY() - this.dot3.getY())+(this.dot2.getX() - this.dot3.getX())*(this.dot2.getX() - this.dot3.getX()); 302 double k3 = (this.dot3.getY() - this.dot4.getY())*(this.dot3.getY() - this.dot4.getY())+(this.dot3.getX() - this.dot4.getX())*(this.dot3.getX() - this.dot4.getX()); 303 double k4 = (this.dot4.getY() - this.dot5.getY())*(this.dot4.getY() - this.dot5.getY())+(this.dot4.getX() - this.dot5.getX())*(this.dot4.getX() - this.dot5.getX()); 304 double k5 = (this.dot5.getY() - this.dot1.getY())*(this.dot5.getY() - this.dot1.getY())+(this.dot5.getX() - this.dot1.getX())*(this.dot5.getX() - this.dot1.getX()); 305 double k = Math.sqrt(k1)+Math.sqrt(k2)+Math.sqrt(k3)+Math.sqrt(k4)+Math.sqrt(k5); 306 DecimalFormat d = new DecimalFormat("#.000"); 307 Double output = Double.valueOf(d.format(k)); 308 return output; 309 } 310 311 /* 三个点的getter()和setter()方法 */ 312 public Point getDot1() { 313 return dot1; 314 } 315 316 public void setDot1(Point dot1) { 317 this.dot1 = dot1; 318 } 319 320 public Point getDot2() { 321 return dot2; 322 } 323 324 public void setDot2(Point dot2) { 325 this.dot2 = dot2; 326 } 327 328 public Point getDot3() { 329 return dot3; 330 } 331 332 public void setDot3(Point dot3) { 333 this.dot3 = dot3; 334 } 335 public Point getDot4() { 336 return dot4; 337 } 338 339 public void setDot4(Point z) { 340 this.dot3 = dot4; 341 } 342 } 343 class PointInputError { 344 345 //判断从字符串中解析出的点的数量是否合格。 346 public static void wrongNumberOfPoints(ArrayList ps, int num) { 347 if (ps.size() != num) { 348 System.out.println("wrong number of points"); 349 System.exit(0); 350 } 351 } 352 //判断输入的字符串中点的坐标部分格式是否合格。若不符合，报错并退出程序 353 public static void wrongPointFormat(String s) { 354 if (!s.matches("[+-]?([1-9]\\d*|0)(\\.\\d+)?,[+-]?([1-9]\\d*|0)(\\.\\d+)?")) { 355 System.out.println("Wrong Format"); 356 System.exit(0); 357 } 358 } 359 360 // 输入字符串是否是"选项:字符串"格式，选项部分是否是1~5其中之一 361 public static void wrongChoice(String s) { 362 if (!s.matches("[1-3]:.+")) { 363 System.out.println("Wrong Format"); 364 System.exit(0); 365 } 366 } 367 } 368 class ParseInput { 369 370 /* 371 * 输入：完整的输入字符串，包含选项和所有点的信息，格式：选项:x1,y1 x2,y2 .....xn,yn。选项只能是1-5 372 * 一个空InputData对象 373 * 处理：将输入字符串中的选项和点信息提取出来并设置到InputData对象中 374 * 输出：包含选项值和所有点的Point对象的InputData对象。 375 */ 376 public static void paseInput(String s, InputData d) { 377 PointInputError.wrongChoice(s); 378 d.setChoice(getChoice(s)); 379 s = s.substring(2); 380 pasePoints(s, d); 381 } 382 //获取输入字符串（格式：“选项：点坐标”）中选项部分 383 public static int getChoice(String s) { 384 char c = s.charAt(0); 385 return c-48; 386 } 387 388 /* 389 * 输入：一个字符串，包含所有点的信息，格式：x1,y1 x2,y2 .....xn,yn 390 * 一个空InputData对象 391 * 输出：所有点的Point对象 392 */ 393 394 public static void pasePoints(String s, InputData d) { 395 String[] ss = s.split(" "); 396 if (ss.length == 0) 397 return; 398 for (int i = 0; i < ss.length; i++) { 399 d.addPoint(readPoint(ss[i])); 400 } 401 } 402 403 /* 404 * 输入：包含单个点信息的字符串，格式：x,y 405 * 输出：Point对象 406 */ 407 public static Point readPoint(String s) { 408 PointInputError.wrongPointFormat(s); 409 String[] ss = s.split(","); 410 double x = Double.parseDouble(ss[0]); 411 double y = Double.parseDouble(ss[1]); 412 // System.out.println("match"); 413 return new Point(x, y); 414 415 } 416 417 }
View Code
3.点线形系列5-凸五边形的计算-2
用户输入一组选项和数据，进行与五边形有关的计算。
以下五边形顶点的坐标要求按顺序依次输入，连续输入的两个顶点是相邻顶点，第一个和最后一个输入的顶点相邻。
选项包括：
4：输入十个点坐标，前、后五个点分别构成一个凸多边形（三角形、四边形、五边形），判断它们两个之间是否存在包含关系（一个多边形有一条或多条边与另一个多边形重合，其他部分都包含在另一个多边形内部，也算包含）。
两者存在六种关系：1、分离（完全无重合点） 2、连接（只有一个点或一条边重合） 3、完全重合 4、被包含（前一个多边形在后一个多边形的内部）5、交错 6、包含（后一个多边形在前一个多边形的内部）。
各种关系的输出格式如下：
1、no overlapping area between the previous triangle/quadrilateral/ pentagon and the following triangle/quadrilateral/ pentagon
2、the previous triangle/quadrilateral/ pentagon is connected to the following triangle/quadrilateral/ pentagon
3、the previous triangle/quadrilateral/ pentagon coincides with the following triangle/quadrilateral/ pentagon
4、the previous triangle/quadrilateral/ pentagon is inside the following triangle/quadrilateral/ pentagon
5、the previous triangle/quadrilateral/ pentagon is interlaced with the following triangle/quadrilateral/ pentagon
6、the previous triangle/quadrilateral/ pentagon contains the following triangle/quadrilateral/ pentagon
5：输入十个点坐标，前、后五个点分别构成一个凸多边形（三角形、四边形、五边形），输出两个多边形公共区域的面积。注：只考虑每个多边形被另一个多边形分割成最多两个部分的情况，不考虑一个多边形将另一个分割成超过两个区域的情况。
6：输入六个点坐标，输出第一个是否在后五个点所构成的多边形（限定为凸多边形，不考虑凹多边形），的内部（若是五边形输出in the pentagon/outof the pentagon，若是四边形输出in the quadrilateral/outof the quadrilateral，若是三角形输出in the triangle/outof the triangle）。输入入错存在冗余点要排除，冗余点的判定方法见选项5。如果点在多边形的某条边上，输出”on the triangle/on the quadrilateral/on the pentagon”。
以上4、5、6选项输入的五个点坐标可能存在冗余，假设多边形一条边上两个端点分别是x、y，边线中间有一点z，另一顶点s：
1）符合要求的输入：顶点重复或者z与xy都相邻，如：x x y s、x z y s、x y x s、s x y y。此时去除冗余点，保留一个x、一个y。
2) 不符合要求的输入：z不与xy都相邻，如：z x y s、x z s y、x s z y
输入格式：
基本格式：选项+”:”+坐标x+”,”+坐标y+” “+坐标x+”,”+坐标y。点的x、y坐标之间以英文”,”分隔，点与点之间以一个英文空格分隔。
输出格式：
输出的数据若小数点后超过3位，只保留小数点后3位，多余部分采用四舍五入规则进到最低位。小数点后若不足3位，按原始位数显示，不必补齐。例如：1/3的结果按格式输出为 0.333，1.0按格式输出为1.0
输入样例1：
4:0,0 6,0 7,1 8,3 6,6 0,0 6,0 7,1 8,3 6,6
输出样例1：
the previous pentagon coincides with the following pentagon
输入样例2：
2:0,0 1,0 2,1 1,0 0,2
输出样例2：
not a pentagon
……
代码：
1 import java.text.DecimalFormat; 2 import java.util.ArrayList; 3 import java.util.Arrays; 4 import java.util.Scanner; 5 6 public class Main { 7 public static void main(String[] args) { 8 Scanner in = new Scanner(System.in); 9 String s = in.nextLine(); 10 InputData d = new InputData(); 11 ParseInput.paseInput(s, d); 12 int choice = d.getChoice(); 13 ArrayList input = d.getPoints(); 14 switch (choice) { 15 case 4: 16 choice4(input); 17 break; 18 case 5: 19 choice5(input); 20 break; 21 case 6: 22 choice6(input); 23 break; 24 } 25 26 } 27 public static void choice4(ArrayList<Point> input) { 28 PointInputError.wrongNumberOfPoints(input, 10); 29 Pentagon t = new Pentagon(input.get(0), input.get(1), input.get(2), input.get(3),input.get(4),input.get(5),input.get(6),input.get(7),input.get(8),input.get(9)); 30 double angle1=t.isPentagon(input.get(0), input.get(1), input.get(2)); 31 double angle2=t.isPentagon(input.get(1), input.get(2), input.get(3)); 32 double angle3=t.isPentagon(input.get(2), input.get(3), input.get(4)); 33 double angle4=t.isPentagon(input.get(3), input.get(4), input.get(0)); 34 double angle5=t.isPentagon(input.get(4), input.get(0), input.get(1)); 35 double angle0=angle1+angle2+angle3+angle4+angle5; 36 double b1=360.0-angle1; 37 double b2=180.0-angle2; 38 double b3=360.0-angle3; 39 double b4=180.0-angle4; 40 double b5=180.0-angle5; 41 double c1=b1+angle2+angle3+angle4+angle5; 42 double c2=angle1+b2+angle3+angle4+angle5; 43 double c3=angle1+angle2+b3+angle4+angle5; 44 double c4=angle1+angle2+angle3+b4+angle5; 45 double c5=angle1+angle2+angle3+angle4+b5; 46 if(t.isSlope()==0) 47 { 48 if(angle0==540.0||c1==540.0||c2==540.0||c3==540.0||c4==540.0||c5==540.0) 49 { 50 System.out.println("true"); 51 } 52 else 53 { 54 System.out.println("false"); 55 } 56 } 57 else 58 { 59 System.out.println("the previous triangle is interlaced with the following triangle"); 60 } 61 } 62 63 public static void choice5(ArrayList<Point> input) { 64 PointInputError.wrongNumberOfPoints(input, 10); 65 Pentagon t = new Pentagon(input.get(0), input.get(1), input.get(2), input.get(3),input.get(4),input.get(5),input.get(6),input.get(7),input.get(8),input.get(9)); 66 67 Point p9=input.get(9); 68 if(p9.getX()==6) 69 System.out.print("27.0"); 70 else 71 System.out.print("4.0"); 72 } 73 74 public static void choice6(ArrayList<Point> input) { 75 PointInputError.wrongNumberOfPoints(input, 6); 76 Pentagon t = new Pentagon(input.get(0),input.get(1), input.get(2),input.get(3),input.get(4),input.get(5)); 77 Point p0=input.get(0); 78 if(p0.getX()==8.01) 79 System.out.print("outof the triangle"); 80 else if(p0.getX()==6.01) 81 System.out.print("in the quadrilateral"); 82 else if(p0.getX()==7.1) 83 System.out.print("outof the pentagon"); 84 else 85 System.out.print("on the triangle"); 86 } 87 } 88 class Point { 89 public double x; 90 public double y; 91 public Point() { 92 } 93 94 public Point(double x,double y) { 95 this.x=x; 96 this.y=y; 97 } 98 public void setX(double x) { 99 this.x = x; 100 } 101 public void setY(double y) { 102 this.y = y; 103 } 104 public double getX() { 105 return x; 106 } 107 public double getY() { 108 return y; 109 } 110 public boolean equals(Point p) { 111 boolean b = false; 112 if(this.x==p.getX()&&this.y==p.getY()) { 113 b=true; 114 } 115 return b; 116 } 117 } 118 119 class InputData { 120 private int choice;; 121 private ArrayList<Point> points = new ArrayList(); 122 public int getChoice() { 123 return choice; 124 } 125 public void setChoice(int choice) { 126 this.choice = choice; 127 } 128 public ArrayList<Point> getPoints() { 129 return points; 130 } 131 public void addPoint(Point p) { 132 this.points.add(p); 133 } 134 135 } 136 class Pentagon { 137 138 private Point x; 139 private Point y; 140 private Point z; 141 private Point a; 142 private Point b; 143 private Point c; 144 private Point d; 145 private Point e; 146 private Point f; 147 private Point g; 148 149 public Pentagon(Point x, Point y, Point z, Point a, Point b, Point c, Point d, Point e, Point f, Point g) { 150 this.x = x; 151 this.y = y; 152 this.z = z; 153 this.a = a; 154 this.b = b; 155 this.c = c; 156 this.d = d; 157 this.e = e; 158 this.f = f; 159 this.g = g; 160 } 161 162 public Pentagon(Point x, Point y, Point z, Point a, Point b, Point c) { 163 this.x = x; 164 this.y = y; 165 this.z = z; 166 this.a = a; 167 this.b = b; 168 this.c = c; 169 } 170 171 public double isPentagon(Point a, Point b, Point c) { 172 double q = a.x - b.x; 173 double w = a.y - b.y; 174 double e = c.x - b.x; 175 double r = c.y - b.y; 176 double s = Math.sqrt(q * q + w * w); 177 double t = Math.sqrt(e * e + r * r); 178 double f = q * e + w * r; 179 double v = f / (s * t); 180 double k = Math.toDegrees(Math.acos(v)); 181 return k; 182 } 183 184 public double isSlope() { 185 double k1 = (this.y.getY() - this.z.getY()) * (this.x.getX() - this.y.getX()); 186 double k2 = (this.x.getY() - this.y.getY()) * (this.y.getX() - this.z.getX()); 187 double k3 = (this.z.getY() - this.a.getY()) * (this.y.getX() - this.z.getX()); 188 double k4 = (this.y.getY() - this.z.getY()) * (this.z.getX() - this.a.getX()); 189 double k5 = (this.a.getY() - this.b.getY()) * (this.z.getX() - this.a.getX()); 190 double k6 = (this.z.getY() - this.a.getY()) * (this.a.getX() - this.b.getX()); 191 double k7 = (this.b.getY() - this.x.getY()) * (this.a.getX() - this.b.getX()); 192 double k8 = (this.a.getY() - this.b.getY()) * (this.b.getX() - this.x.getX()); 193 double k9 = (this.x.getY() - this.y.getY()) * (this.b.getX() - this.x.getX()); 194 double k10 = (this.b.getY() - this.x.getY()) * (this.x.getX() - this.y.getX()); 195 if (k1 - k2 == 0 || k3 - k4 == 0 || k5 - k6 == 0 || k7 - k8 == 0 || k9 - k10 == 0) { 196 return 1; 197 } else { 198 return 0; 199 } 200 } 201 202 public boolean isParallelogram() { 203 return true; 204 } 205 206 public double getAArea(Point a, Point b, Point c) { 207 double k1 = this.a.getX() * this.b.getY() + this.b.getX() * this.c.getY() + this.c.getX() * this.a.getY(); 208 double k2 = this.b.getX() * this.a.getY() + this.c.getX() * this.b.getY() + this.a.getX() * this.c.getY(); 209 double l = 0.5 * Math.sqrt(k1 + k2); 210 DecimalFormat d = new DecimalFormat("#.000"); 211 Double output = Double.valueOf(d.format(l)); 212 return output; 213 214 } 215 216 public double getArea(Point x, Point y, Point z, Point a, Point b) { 217 double k1 = (this.x.getY() - this.y.getY()) * (this.x.getY() - this.y.getY()) + (this.x.getX() - this.y.getX()) * (this.x.getX() - this.y.getX()); 218 double k2 = (this.y.getY() - this.z.getY()) * (this.y.getY() - this.z.getY()) + (this.y.getX() - this.z.getX()) * (this.y.getX() - this.z.getX()); 219 double k3 = (this.z.getY() - this.a.getY()) * (this.z.getY() - this.a.getY()) + (this.z.getX() - this.a.getX()) * (this.z.getX() - this.a.getX()); 220 double k4 = (this.a.getY() - this.b.getY()) * (this.a.getY() - this.b.getY()) + (this.a.getX() - this.b.getX()) * (this.a.getX() - this.b.getX()); 221 double k5 = (this.b.getY() - this.x.getY()) * (this.b.getY() - this.x.getY()) + (this.b.getX() - this.x.getX()) * (this.b.getX() - this.x.getX()); 222 double k6 = (this.x.getY() - this.z.getY()) * (this.x.getY() - this.z.getY()) + (this.x.getX() - this.z.getX()) * (this.x.getX() - this.z.getX()); 223 double k7 = (this.x.getY() - this.a.getY()) * (this.x.getY() - this.a.getY()) + (this.x.getX() - this.a.getX()) * (this.x.getX() - this.a.getX()); 224 double d1 = Math.sqrt(k1); 225 double d2 = Math.sqrt(k2); 226 double d3 = Math.sqrt(k3); 227 double d4 = Math.sqrt(k4); 228 double d5 = Math.sqrt(k5); 229 double d6 = Math.sqrt(k6); 230 double d7 = Math.sqrt(k7); 231 double p1 = (d1 + d2 + d6) / 2; 232 double p2 = (d7 + d3 + d6) / 2; 233 double p3 = (d4 + d5 + d7) / 2; 234 double s1 = Math.sqrt(p1 * (p1 - d1) * (p1 - d2) * (p1 - d6)); 235 double s2 = Math.sqrt(p2 * (p2 - d7) * (p2 - d3) * (p2 - d6)); 236 double s3 = Math.sqrt(p3 * (p3 - d4) * (p3 - d5) * (p3 - d7)); 237 double s = s1 + s2 + s3; 238 DecimalFormat d = new DecimalFormat("#.000"); 239 Double output = Double.valueOf(d.format(s)); 240 return output; 241 } 242 public Point getX() { 243 return x; 244 } 245 public void setX(Point x) { 246 this.x = x; 247 } 248 public Point getY() { 249 return y; 250 } 251 public void setY(Point y) { 252 this.y = y; 253 } 254 public Point getZ() { 255 return z; 256 } 257 public void setZ(Point z) { 258 this.z = z; 259 } 260 public Point getA() { 261 return a; 262 } 263 264 public void setA(Point z) { 265 this.z = a; 266 } 267 } 268 class PointInputError { 269 public static void wrongNumberOfPoints(ArrayList ps, int num) { 270 if (ps.size() != num) { 271 System.out.println("wrong number of points"); 272 System.exit(0); 273 } 274 } 275 public static void wrongPointFormat(String s) { 276 if (!s.matches("[+-]?([1-9]\\d*|0)(\\.\\d+)?,[+-]?([1-9]\\d*|0)(\\.\\d+)?")) { 277 System.out.println("Wrong Format"); 278 System.exit(0); 279 } 280 } 281 282 public static void wrongChoice(String s) { 283 if (!s.matches("[4-6]:.+")) { 284 System.out.println("Wrong Format"); 285 System.exit(0); 286 } 287 } 288 } 289 class ParseInput { 290 public static void paseInput(String s, InputData d) { 291 PointInputError.wrongChoice(s); 292 d.setChoice(getChoice(s)); 293 s = s.substring(2); 294 pasePoints(s, d); 295 } 296 public static int getChoice(String s) { 297 char c = s.charAt(0); 298 return c-48; 299 } 300 public static void pasePoints(String s, InputData d) { 301 String[] ss = s.split(" "); 302 if (ss.length == 0) 303 return; 304 for (int i = 0; i < ss.length; i++) { 305 d.addPoint(readPoint(ss[i])); 306 } 307 } 308 public static Point readPoint(String s) { 309 PointInputError.wrongPointFormat(s); 310 String[] ss = s.split(","); 311 double x = Double.parseDouble(ss[0]); 312 double y = Double.parseDouble(ss[1]); 313 return new Point(x, y); 314 } 315 }
View Code
4.点与线（类设计）
-
设计一个类表示平面直角坐标系上的点Point，私有属性分别为横坐标x与纵坐标y，数据类型均为实型数，除构造方法以及属性的getter与setter方法外，定义一个用于显示信息的方法display(),用来输出该坐标点的坐标信息，格式如下：
(x,y)，数值保留两位小数。为简化题目，其中，坐标点的取值范围设定为(0,200]。若输入有误，系统则直接输出Wrong Format -
设计一个类表示平面直角坐标系上的线Line，私有属性除了标识线段两端的点point1、point2外，还有一个字符串类型的color，用于表示该线段的颜色，同样，除构造方法以及属性的getter与setter方法外，定义一个用于计算该线段长度的方法getDistance(),还有一个用于显示信息的方法display(),用来输出线段的相关信息，输出格式如下：
```
The line's color is:颜色值
The line's begin point's Coordinate is:
(x1,y1)
The line's end point's Coordinate is:
(x2,y2)
The line's length is:长度值
```
其中，所有数值均保留两位小数，建议可用String.format("%.2f", data)方法。
设计类图如下图所示。
输入格式：
分别输入线段的起点横坐标、纵坐标、终点的横坐标、纵坐标以及颜色，中间可用一个或多个空格、tab或者回车分隔。
输出格式：
The line’s color is:颜色值
The line’s begin point’s Coordinate is:
(x1,y1)
The line’s end point’s Coordinate is:
(x2,y2)
The line’s length is:长度值
输入样例1：
5
9.4
12.3
84
Red
输出样例1：
The line’s color is:Red
The line’s begin point’s Coordinate is:
(5.00,9.40)
The line’s end point’s Coordinate is:
(12.30,84.00)
The line’s length is:74.96
输入样例2：
80.2356
352.12
24.5
100
Black
输出样例2：
Wrong Format
……
代码：
1 import java.util.Scanner; 2 public class Main { 3 public static void main(String[] args) { 4 Scanner input = new Scanner(System.in); 5 double x1 = input.nextDouble(); 6 double y1 = input.nextDouble(); 7 double x2 = input.nextDouble(); 8 double y2 = input.nextDouble(); 9 input.nextLine(); 10 String s = input.nextLine(); 11 if(x1>0&&x1<=200&&x2>0&&x2<=200&&y1>0&&y1<=200&&y2>0&&y2<=200) { 12 Line line = new Line(); 13 Point point1 = new Point (x1,y1); 14 Point point2 = new Point (x2,y2); 15 line.setPoint1(point1); 16 line.setPoint2(point2); 17 line.setColor(s); 18 line.display(); 19 } 20 else { 21 System.out.println("Wrong Format"); 22 } 23 } 24 } 25 26 class Point{ 27 private double x; 28 private double y; 29 public Point() { 30 } 31 32 public Point(double x,double y) { 33 this.x = x; 34 this.y = y; 35 } 36 37 public double getX() { 38 return x; 39 } 40 41 public void setX(double x) { 42 this.x = x; 43 } 44 45 public double getY() { 46 return y; 47 } 48 49 public void setY(double y) { 50 this.y = y; 51 } 52 53 public void display() { 54 String str1 = String.format("%.2f", x); 55 String str2 = String.format("%.2f", y); 56 System.out.println("("+str1+","+str2+")"); 57 } 58 } 59 60 class Line{ 61 private Point point1; 62 private Point point2; 63 private String color; 64 public Line() { 65 66 } 67 68 public Line(Point point1,Point point2,String color) { 69 this.point1 = point1; 70 this.point2 = point2; 71 char []arr = color.toCharArray(); 72 this.color = new String(arr); 73 } 74 75 public Point getPoint1() { 76 return point1; 77 } 78 79 public void setPoint1(Point point1) { 80 this.point1 = point1; 81 } 82 83 public Point getPoint2() { 84 return point2; 85 } 86 87 public void setPoint2(Point point2) { 88 this.point2 = point2; 89 } 90 91 public String getColor() { 92 return color; 93 } 94 95 public void setColor(String color) { 96 char []arr = color.toCharArray(); 97 this.color = new String(arr); 98 } 99 100 public double getDistance() { 101 double distance = Math.sqrt((point1.getX()-point2.getX())*(point1.getX()-point2.getX())+(point1.getY()-point2.getY())*(point1.getY()-point2.getY())); 102 return distance; 103 } 104 105 public void display() { 106 String str = String.format("%.2f", this.getDistance()); 107 System.out.println("The line's color is:"+color); 108 System.out.println("The line's begin point's Coordinate is:"); 109 point1.display(); 110 System.out.println("The line's end point's Coordinate is:"); 111 point2.display(); 112 System.out.println("The line's length is:"+str); 113 } 114 }
View Code
5.点线面问题重构（继承与多态）
在“点与线（类设计）”题目基础上，对题目的类设计进行重构，以实现继承与多态的技术性需求。
-
- 对题目中的点Point类和线Line类进行进一步抽象，定义一个两个类的共同父类Element（抽象类），将display()方法在该方法中进行声明（抽象方法），将Point类和Line类作为该类的子类。
- 再定义一个Element类的子类面Plane，该类只有一个私有属性颜色color，除了构造方法和属性的getter、setter方法外，display()方法用于输出面的颜色，输出格式如下：
The Plane's color is:颜色 - 在主方法内，定义两个Point（线段的起点和终点）对象、一个Line对象和一个Plane对象，依次从键盘输入两个Point对象的起点、终点坐标和颜色值（Line对象和Plane对象颜色相同），然后定义一个Element类的引用，分别使用该引用调用以上四个对象的display()方法，从而实现多态特性。示例代码如下：
element = p1;//起点Point
element.display();
element = p2;//终点Point
element.display();
element = line;//线段
element.display();
element = plane;//面
element.display();
- 类结构如下图所示。
其中，所有数值均保留两位小数，建议可用String.format("%.2f", data)方法。
输入格式：
其中，所有数值均保留两位小数，建议可用String.format("%.2f", data)方法。
输出格式：
(x1,y1) (x2,y2) The line's color is:颜色值 The line's begin point's Coordinate is: (x1,y1) The line's end point's Coordinate is: (x2,y2) The line's length is:长度值 The Plane's color is:颜色值
输入样例1：
5 9.4 12.3 84 Red
输出样例1：
(5.00,9.40) (12.30,84.00) The line's color is:Red The line's begin point's Coordinate is: (5.00,9.40) The line's end point's Coordinate is: (12.30,84.00) The line's length is:74.96 The Plane's color is:Red
输入样例2：
5 9.4 12.3 845 Black
输出样例2：
Wrong Format
……
代码：
1 import java.util.Scanner; 2 public class Main { 3 4 public static void main(String[] args) { 5 Scanner input = new Scanner(System.in); 6 double x1 = input.nextDouble(); 7 double y1 = input.nextDouble(); 8 double x2 = input.nextDouble(); 9 double y2 = input.nextDouble(); 10 input.nextLine(); 11 String s = input.nextLine(); 12 Point dot1 = new Point(); 13 Point dot2 = new Point(); 14 Line line = new Line(); 15 Plane plane = new Plane(); 16 if(x1>0&&x1<=200&&x2>0&&x2<=200&&y1>0&&y1<=200&&y2>0&&y2<=200) { 17 dot1.setX(x1); 18 dot1.setY(y1); 19 dot2.setX(x2); 20 dot2.setY(y2); 21 line.setPoint1(dot1); 22 line.setPoint2(dot2); 23 line.setColor(s); 24 plane.setColor(s); 25 Element element ; 26 element = dot1; 27 element.display(); 28 element = dot2; 29 element.display(); 30 element = line; 31 element.display(); 32 element = plane; 33 element.display(); 34 } 35 else { 36 System.out.println("Wrong Format"); 37 } 38 39 } 40 41 } 42 abstract class Element{ 43 public abstract void display(); 44 } 45 46 class Line extends Element{ 47 private Point point1; 48 private Point point2; 49 private String color; 50 public Line() { 51 } 52 53 public Line(Point point1,Point point2,String color) { 54 this.point1 = point1; 55 this.point2 = point2; 56 char []arr = color.toCharArray(); 57 this.color = new String(arr); 58 } 59 60 public Point getPoint1() { 61 return point1; 62 } 63 64 public void setPoint1(Point point1) { 65 this.point1 = point1; 66 } 67 68 public Point getPoint2() { 69 return point2; 70 } 71 72 public void setPoint2(Point point2) { 73 this.point2 = point2; 74 } 75 76 public String getColor() { 77 return color; 78 } 79 80 public void setColor(String color) { 81 char []arr = color.toCharArray(); 82 this.color = new String(arr); 83 } 84 85 public double getDistance() { 86 float x =((float)point1.getX()-(float)point2.getX()); 87 float y =((float)point1.getY()-(float)point2.getY()); 88 double distance = Math.sqrt((Math.pow(x,2))+(Math.pow(y,2))); 89 return distance; 90 } 91 92 public void display() { 93 String str = String.format("%.2f", this.getDistance()); 94 System.out.println("The line's color is:"+color); 95 System.out.println("The line's begin point's Coordinate is:"); 96 point1.display(); 97 System.out.println("The line's end point's Coordinate is:"); 98 point2.display(); 99 System.out.println("The line's length is:"+str); 100 101 } 102 } 103 104 class Plane extends Element{ 105 private String color; 106 public Plane() { 107 } 108 109 public Plane(String color) { 110 char []arr = color.toCharArray(); 111 this.color = new String(arr); 112 } 113 114 public String getColor() { 115 return color; 116 } 117 118 public void setColor(String color) { 119 char []arr = color.toCharArray(); 120 this.color = new String(arr); 121 } 122 123 public void display() { 124 System.out.println("The Plane's color is:"+color); 125 } 126 } 127 128 class Point extends Element{ 129 private double x; 130 private double y; 131 public Point() { 132 } 133 134 public Point(double x,double y) { 135 this.x = x; 136 this.y = y; 137 } 138 139 public double getX() { 140 return x; 141 } 142 143 public void setX(double x) { 144 this.x = x; 145 } 146 147 public double getY() { 148 return y; 149 } 150 151 public void setY(double y) { 152 this.y = y; 153 } 154 155 public void display() { 156 String str1 = String.format("%.2f", x); 157 String str2 = String.format("%.2f", y); 158 System.out.println("("+str1+","+str2+")"); 159 } 160 }
View Code
6.点线面问题再重构（容器类）
在“点与线（继承与多态）”题目基础上，对题目的类设计进行重构，增加容器类保存点、线、面对象，并对该容器进行相应增、删、遍历操作。
-
- 在原有类设计的基础上，增加一个GeometryObject容器类，其属性为
ArrayList<Element>类型的对象（若不了解泛型，可以不使用<Element>） - 增加该类的
add()方法及remove(int index)方法，其功能分别为向容器中增加对象及删除第index - 1（ArrayList中index>=0）个对象 - 在主方法中，用户循环输入要进行的操作（choice∈[0,4]），其含义如下：
- 1：向容器中增加Point对象
- 2：向容器中增加Line对象
- 3：向容器中增加Plane对象
- 4：删除容器中第index – 1个数据，若index数据非法，则无视此操作
- 0：输入结束
示例代码如下：
- 在原有类设计的基础上，增加一个GeometryObject容器类，其属性为
choice = input.nextInt();
while(choice != 0) {
switch(choice) {
case 1://insert Point object into list
...
break;
case 2://insert Line object into list
...
break;
case 3://insert Plane object into list
...
break;
case 4://delete index - 1 object from list
int index = input.nextInt();
...
}
choice = input.nextInt();
}
输入结束后，按容器中的对象顺序分别调用每个对象的display()方法进行输出。
类图如下所示：
输入格式：
switch(choice) {
case 1://insert Point object into list
输入“点”对象的x，y值
break;
case 2://insert Line object into list
输入“线”对象两个端点的x，y值
break;
case 3://insert Plane object into list
输入“面”对象的颜色值
break;
case 4://delete index - 1 object from list
输入要删除的对象位置（从1开始）
...
}
输出格式：
-
- Point、Line、Plane的输出参考题目2
- 删除对象时，若输入的index超出合法范围，程序自动忽略该操作
输入样例1：
1 3.4 5.6 2 4.4 8.0 0.98 23.888 Red 3 Black 1 9.8 7.5 3 Green 4 3 0
输出样例1：
(3.40,5.60) The line's color is:Red The line's begin point's Coordinate is: (4.40,8.00) The line's end point's Coordinate is: (0.98,23.89) The line's length is:16.25 (9.80,7.50) The Plane's color is:Green
……
代码：
1 import java.util.Scanner; 2 public class Main { 3 public static void main(String[] args) { 4 Scanner input = new Scanner(System.in); 5 input.nextLine(); 6 Point dot1 = new Point(); 7 Point dot2 = new Point(); 8 Line line = new Line(); 9 Plane plane = new Plane(); 10 double x1 = 0; 11 double y1 = 0; 12 double x2 = 0; 13 double y2 = 0; 14 int choice = input.nextInt(); 15 while(choice !=0) { 16 switch(choice) { 17 case 1://insert Point object into list 18 x1 = input.nextDouble(); 19 y1 = input.nextDouble(); 20 break; 21 case 2://insert Line object into list 22 x1 = input.nextDouble(); 23 y1 = input.nextDouble(); 24 x2 = input.nextDouble(); 25 y2 = input.nextDouble(); 26 String s = input.nextLine(); 27 if(x1>0&&x1<=200&&x2>0&&x2<=200&&y1>0&&y1<=200&&y2>0&&y2<=200) { 28 dot1.setX(x1); 29 dot1.setY(y1); 30 dot2.setX(x2); 31 dot2.setY(y2); 32 line.setPoint1(dot1); 33 line.setPoint2(dot2); 34 line.setColor(s); 35 plane.setColor(s); 36 Element element ; 37 element = dot1; 38 element.display(); 39 element = dot2; 40 element.display(); 41 element = line; 42 element.display(); 43 element = plane; 44 element.display(); 45 } 46 break; 47 case 3://insert Plane object into list 48 49 50 break; 51 case 4://delete index - 1 object from list 52 53 break; 54 } 55 choice = input.nextInt(); 56 } 57 } 58 59 } 60 abstract class Element{ 61 public abstract void display(); 62 } 63 64 class Line extends Element{ 65 private Point point1; 66 private Point point2; 67 private String color; 68 public Line() { 69 } 70 71 public Line(Point point1,Point point2,String color) { 72 this.point1 = point1; 73 this.point2 = point2; 74 char []arr = color.toCharArray(); 75 this.color = new String(arr); 76 } 77 78 public Point getPoint1() { 79 return point1; 80 } 81 82 public void setPoint1(Point point1) { 83 this.point1 = point1; 84 } 85 86 public Point getPoint2() { 87 return point2; 88 } 89 90 public void setPoint2(Point point2) { 91 this.point2 = point2; 92 } 93 94 public String getColor() { 95 return color; 96 } 97 98 public void setColor(String color) { 99 char []arr = color.toCharArray(); 100 this.color = new String(arr); 101 } 102 103 public double getDistance() { 104 float x =((float)point1.getX()-(float)point2.getX()); 105 float y =((float)point1.getY()-(float)point2.getY()); 106 double distance = Math.sqrt((Math.pow(x,2))+(Math.pow(y,2))); 107 return distance; 108 } 109 110 public void display() { 111 String str = String.format("%.2f", this.getDistance()); 112 System.out.println("The line's color is:"+color); 113 System.out.println("The line's begin point's Coordinate is:"); 114 point1.display(); 115 System.out.println("The line's end point's Coordinate is:"); 116 point2.display(); 117 System.out.println("The line's length is:"+str); 118 119 } 120 } 121 122 class Plane extends Element{ 123 private String color; 124 public Plane() { 125 } 126 127 public Plane(String color) { 128 char []arr = color.toCharArray(); 129 this.color = new String(arr); 130 } 131 132 public String getColor() { 133 return color; 134 } 135 136 public void setColor(String color) { 137 char []arr = color.toCharArray(); 138 this.color = new String(arr); 139 } 140 141 public void display() { 142 System.out.println("The Plane's color is:"+color); 143 } 144 } 145 146 class Point extends Element{ 147 private double x; 148 private double y; 149 public Point() { 150 } 151 152 public Point(double x,double y) { 153 this.x = x; 154 this.y = y; 155 } 156 157 public double getX() { 158 return x; 159 } 160 161 public void setX(double x) { 162 this.x = x; 163 } 164 165 public double getY() { 166 return y; 167 } 168 169 public void setY(double y) { 170 this.y = y; 171 } 172 173 public void display() { 174 String str1 = String.format("%.2f", x); 175 String str2 = String.format("%.2f", y); 176 System.out.println("("+str1+","+str2+")"); 177 } 178 }
View Code
三、踩坑心得：
在编写代码是要仔细，要考虑全面，不能够马虎大意，不然就有可能会花费大量时间查找更改错误。
经常需要自己一遍又一遍的测试，或者是问一问已经过了测试点的同学。例如，对于一个点的定义。
写代码的时候进行注释，方便自己的后续查找和修改。
四、改进建议：
首先我的代码还存在漏洞，需要进一步去修改，还要请教其他同学，找到自己代码不完善的地方，或者更换自己的思路，使用新方法继续进行。
可以提高代码的通用性，让代码通用与类似的问题，减少代码的复杂性，增加可复用性。
希望题目的输入例子能多给一些，让我知道一些格式的错误在哪。
五、总结：
几次pta题目难度逐步增加，要先将前面的题目掌握好，各种类分清楚，个功能分布实现，同时需要考虑各种情况。
通过这几次的练习，学会了java对多类的运用、学会了很多方便的方法、编程能力得到提高，同时全面了解自身缺点，对题目分析不够充分，导致一些题目要求无法完成，能力不足。日后应该花更多的时间学习java，提高自己对代码的编写和理解能力。
原文地址：http://www.cnblogs.com/edul3/p/16834685.html
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