java题目这样做为什么三角形部分无法构成三角型时会死循环

Question

package student;
import java.util.Scanner;
public class mianji {
public static void main(String[] args){
    System.out.println("形状的类型\n1.长方形\n2.圆形\n3.三角形\n4.退出");
    Scanner scan=new Scanner(System.in);
    int a=scan.nextInt();
    if(a<=4&&a>=1){
        switch(a){
        case 1:
            System.out.println("Please enter length");
            float b=scan.nextFloat();
            System.out.println("Please enter highth");
            float c=scan.nextFloat();
            if(b>=0&&c>=0){
                System.out.println("Area of the rectangle is:"+(c*b));
            }else{System.out.println("b and c can't be zero");}
        case 2:
            System.out.println("Please enter redius");
            float d=scan.nextFloat();
            if(d>=0){
                System.out.println("Area of the cylnder is:"+(d*d*Math.PI));
            }else{System.out.println("d can't be zero");}
        case 3:
            System.out.println("Plese enter A");
            float A=scan.nextFloat();
            System.out.println("Plese enter B");
            float B=scan.nextFloat();
            System.out.println("Plese enter C");
            float C=scan.nextFloat();
            if(A>=0&&B>=0&&C>=0){
                while(true){if(A+B>C){
                float p=(A+B+C)/2;
                float sum=(float) Math.sqrt((p*(p-A)*(p-B)*(p-C)));
                System.out.println("The triangle area is "+sum);
                }
                else{
                    System.out.println("Three sides can not constitute a triangle");
                }
            }}else{
                System.out.println("A,B,C can't be zero");
            }
        case 4:
            System.out.println("Bye Bye");
            }

        }
    else{
        System.out.println("Please enter 1~4 number");
    }
}

}

三角形部分是case 3 ；然后要怎么弄才能可以计算完条回到选择形状的界面继续算

Answer 1

我记得swtich是要加break的