标题：程序代码——要求用户输入任意个数，以输入0结束，并打印平均值

public class exec
{
        public static void main( String args[] ) throws Exception
        {
                int amount=0;
                int counter=0;
                
                while(true)
                {
                        int i=Integer.parseInt(javax.swing.JOptionPane.showInputDialog("Please input the number(end with zero)"));
                        if(i==0)
                                break;
                        amount=amount+i;
                        counter++;
                }
                
                String str=String.valueOf((double)amount/counter);
                javax.swing.JOptionPane.showMessageDialog(null,str);
                
                System.exit(0);
        }
}

对于退出循环的比较可以直接使用字符串比较，方法是利用String变量中的equals方法，而不是 s=="0"
public class exec
{
        public static void main( String args[] ) throws Exception
        {
                int amount=0;
                int counter=0;
                
                while(true)
                {
                        String s=javax.swing.JOptionPane.showInputDialog("Please input the number(end with zero)");
                        
                        if(s.equals("0"))
                                break;
                                
                        int i=Integer.parseInt(s);              
                        amount=amount+i;
                        counter++;
                }
                
                String str=String.valueOf((double)amount/counter);
                javax.swing.JOptionPane.showMessageDialog(null,str);
                
                System.exit(0);
        }
}