求解，谢谢各位

import java.util.Scanner;

public class China {
    public static void main(String[] args) {
        int A,B,C;
        boolean boo=true;
        boolean boo2=true;
        String demo;
        Scanner input=new Scanner(System.in);
        do{
             System.out.printf("请输入需要相加的数：");
             A=input.nextInt();
             System.out.printf("请输入需要相加的数：");
             B=input.nextInt();
             C=A+B;
             System.out.println(A+"和"+B+"相加的和是:"+C);
             do{
                 System.out.println("是否继续？y/n");
                 demo = input.next();
                 if(demo.equals("y")||demo.equals("n")){
                     if(demo.equals("n")){
                         boo = false;
                         boo2= false;
                     }else if(demo.equals("y")){
                         boo=true;
                         boo2=false;
                     }
                 }else{
                     System.out.println("输入不正确，请重新输入！");
                 }
             }while(boo2);
        }while(boo);
    }
}
把2楼的完善了一下