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所以对于这个程序，我必须使用一个方法，如果第一个圆圈较小，则返回 -1，如果两个圆圈大小相同，则返回 0，如果第一个圆圈较大，则返回 1。基于此方法的返回值，main 方法应打印一行输出，如：绿色圆圈小于红色圆圈。

   but i dont know how to program it to where 

    if (r1 > r2)
       return -1;

    so that the main method prints

   r1 is bigger then r2



   BEFORE CHANGES this is what i had when i asked the question




        import java .awt.*; // for the graphics classs
        import java .util.*;// for scanner class
       public class Circles{
        public static void main(String[] args){
        Scanner input = new Scanner(System.in); //scanner object
        DrawingPanel panel=new DrawingPanel(400,300);
        Graphics gObject = panel.getGraphics(); //grahics object
       // get info on circles
       System.out.println("please enter your coordnates for the blue circle");
       int x1=input.nextInt();
       int y1=input.nextInt();
        System.out.println("please enter your radius for the blue circle");
        int r1=input.nextInt();
        System.out.println("please enter your coordnates for the red circle");
        int x2=input.nextInt();
        int y2=input.nextInt();
         System.out.println("please enter your radius for the red circle");
       int r2=input.nextInt();
       System.out.println("please enter your coordnates for the pink circle");
       int x3=input.nextInt();
       int y3=input.nextInt();
       System.out.println("please enter your radius for the pink circle");
       int r3=input.nextInt();
       gObject.setColor(Color.BLUE);
       drawCircle(gObject,x1 ,y1 ,r1);
       gObject.setColor(Color.RED);
      drawCircle(gObject,x2,y2,r2);
      gObject.setColor(Color.PINK);
      drawCircle(gObject,x3,y3,r3);
      compare(r1,r2);
      compare(r1,r3);
      compare(r2,r3);

       }//end of main

      public static void drawCircle(Graphics g, int x1 , int y1 , int r1){
      int X1 = (x1-r1);
      int Y1 = (y1 - r1);

      g.fillOval(X1 , Y1 , 2*r1 , 2*r1);
      }//end of drawcircle
       //start of compare
       public static void compare(int r1 , int r2){
       if (r1<r2){
       System.out.println("Second circle is bigger then The First");

        }
         else if (r1 == r2){
           System.out.println("the circles are the same");

         }
          else if (r1 > r2){
            System.out.println("Second is smaller then First");

            }

       }}

这是由于某种原因增加了错误的修改

         import java .awt.*; // for the graphics classs
        import java .util.*;// for scanner class
       public class Circles{
        public static void main(String[] args){
        Scanner input = new Scanner(System.in); //scanner object
        DrawingPanel panel=new DrawingPanel(400,300);
        Graphics gObject = panel.getGraphics(); //grahics object
          // get info on circles
         System.out.println("please enter your coordnates for the blue circle");
         int x1=input.nextInt();
         int y1=input.nextInt();
         System.out.println("please enter your radius for the blue circle");
         int r1=input.nextInt();
         System.out.println("please enter your coordnates for the red circle");
         int x2=input.nextInt();
         int y2=input.nextInt();
         System.out.println("please enter your radius for the red circle");
         int r2=input.nextInt();
         System.out.println("please enter your coordnates for the pink circle");
         int x3=input.nextInt();
         int y3=input.nextInt();
         System.out.println("please enter your radius for the pink circle");
         int r3=input.nextInt();
          gObject.setColor(Color.BLUE);
          drawCircle(gObject,x1 ,y1 ,r1);
          gObject.setColor(Color.RED);
         drawCircle(gObject,x2,y2,r2);
         gObject.setColor(Color.PINK);
         drawCircle(gObject,x3,y3,r3);
        compare(r1,r2);
          compare(r1,r3);
         compare(r2,r3);
         int cmpResult = compare(r1, r2);
          if (cmpResult == -1) {
         System.out.println("r1 is smaller then r2");
         } else if (cmpResult == 0) {
         System.out.println("r1 and r2 are the same");
          } else {
          System.out.println("r1 is bigger then r2");
         }
          System.out.println("Second circle is bigger then The First");
          }//end of main

         public static void drawCircle(Graphics g, int x1 , int y1 , int r1 ){
           int X1 = (x1-r1);
         int Y1 = (y1 - r1);

          g.fillOval(X1 , Y1 , 2*r1 , 2*r1);
          }//end of drawcircle
          //start of compare
          public static int compare(int r1 , int r2, cmpResult){
        if (r1<r2){
         return -1;

          }
            else if (r1 == r2){
          return 0;

         }
          else if (r1 > r2){
          return 1;

          }

            }   }

这是它给我的错误

      3 errors found:
    File: J:\CS Projects\Circles.java  [line: 49]
    Error: Syntax error, insert "}" to complete ClassBody
   File: J:\CS Projects\Circles.java  [line: 51]
    Error: Syntax error on token "cmpResult", VariableDeclaratorId expected after this token
   File: J:\CS Projects\Circles.java  [line: 65]
   Error: Syntax error on token "}", delete this token

希望这很清楚......如果你们需要我发布我到目前为止的代码，我会

4

2 回答 2

3

您假设compareTo的方法用（不是这样的）特殊代码“编码”比较结果：

  • 当第一个圆圈变小时，它需要返回-1，
  • 当圆圈相同时，需要返回0
  • 当第一个圆圈更大时，它需要返回1。

这意味着 main 方法应该进行相同的解码：

  • 当它看到时-1，它必须打印“smaller”，
  • 当它看到时0，它必须打印“相同”，并且
  • 当它看到时1，它必须打印“greater”。

所有这些都可以通过一系列if- then-else语句来完成：

int cmpResult = compareTo(r1, r2);
if (cmpResult == -1) {
    System.out.println("r1 is smaller then r2");
} else if (cmpResult == 0) {
    System.out.println("r1 and r2 are the same");
} else {
    System.out.println("r1 is bigger then r2");
}
于 2013-03-20T01:18:37.627 回答
2

如果a=5; b=6. a>b返回boolean值，所以你可以这样写：

    int compare_radius(int a, int b)
    {  
        return (a > b ? 1 : (a < b ? -1 : 0));
    }

(condition)? val1 : val2被称为ternary运算符。如果条件是true，则返回val1else val2。在你的情况下，如果a > b它返回1else 它将检查a < b，如果这个 true 然后返回-1else 它将0返回a == b

于 2013-03-20T01:48:09.703 回答