Java压缩一些代码

Question

对于 Java 来说非常陌生，我希望更改以下内容以允许相同的变量调用仅发生一次。

第二个“b”变量仅在矩形和三角形期间被调用。这确实有效，只是想看看我是否可以从主干线中取出一行额外的线。

“b”变量无法从 if 语句中移出，因为用户只会输入 a 变量，因此程序将无法启动。

import java.util.*;

public class Main {

    public static void main(String[]args) {
        Scanner in = new Scanner(System.in);
        System.out.print("? ");
        String word = in.next();    
        Shape s = null;
        while (!word.equals("quit")) {
            double a = in.nextDouble();
            if (word.equals("triangle")){
                double b = in.nextDouble();
                s = new Shapet (a, b);
            }else if (word.equals("rectangle")){
                double b = in.nextDouble();
                s = new Shaper (a, b);          
            }else if (word.equals("square")){
                s = new Shapes (a);             
            }else if (word.equals("circle")){
                s = new Shapec (a);             
            }else if (word.equals("pentagon")){
                s = new Shapep (a);             
            }
            System.out.printf("Area of %s = %.2f\n", s, s.area());      
            System.out.print("? ");
            word = in.next();
        }
    }
}

Answer 1

您可以使用 switch，这不会使代码更短但更具可读性:

String word = in.next();    
Shape s = null;
while (!word.equals("quit")) {
   double a = in.nextDouble();
   switch(word) {
    case "triangle":
        s = new Shapet (a, in.nextDouble());
        break;
    case "rectangle":
        s = new Shaper (a, in.nextDouble());    
        break;      
    case "square":
        s = new Shapes (a); 
        break;            
    case "circle":
        s = new Shapec (a);  
        break;           
    case "pentagon":
        s = new Shapep (a);      
        break;       
   }
   word = in.next(); 
 }