我正在嘗試循環

Question

import javax.swing.JOptionPane;
public class New {
    public static void main (String[] args) { 
        String name = JOptionPane.showInputDialog("Enter your name... ");
        do{JOptionPane.showInputDialog( "YOUR NAME...");}
        while(name.equals(""));

        JOptionPane.showMessageDialog(null, "Hello and welcome!, "+name);

        int age = Integer.parseInt(JOptionPane.showInputDialog("Enter your age... "));
        if(age>=60) { JOptionPane.showMessageDialog(null, "Ok Boomer!");
        System.exit(0);}
        else if(age>=18) { JOptionPane.showMessageDialog(null, "You are an adult, Welcome!");
        }
        else { JOptionPane.showMessageDialog(null, "You are a kid!");
        System.exit(0);}

        String day = JOptionPane.showInputDialog("What's the day? ");

        if(day.equals("Monday")) { JOptionPane.showMessageDialog(null, "Welcome to Java club!");
        }
        else {JOptionPane.showMessageDialog(null, "Try again later!");
        }
        
    }
}

我希望我的循環在沒有輸入名稱時開始並在有名稱時結束，即使我輸入名稱它也會讓我保持循環（我是初學者）

Answer 1

我想你忘了在 do while 循環中設置 name 變量。 嘗試這個：

import javax.swing.JOptionPane;
public class New {
    public static void main (String[] args) { 
        String name = JOptionPane.showInputDialog("Enter your name... ");
        while(name.equals("")){
             name=JOptionPane.showInputDialog( "YOUR NAME...");
        }
        

        JOptionPane.showMessageDialog(null, "Hello and welcome!, "+name);

        int age = Integer.parseInt(JOptionPane.showInputDialog("Enter your age... "));
        if(age>=60) { JOptionPane.showMessageDialog(null, "Ok Boomer!");
        System.exit(0);}
        else if(age>=18) { JOptionPane.showMessageDialog(null, "You are an adult, Welcome!");
        }
        else { JOptionPane.showMessageDialog(null, "You are a kid!");
        System.exit(0);}

        String day = JOptionPane.showInputDialog("What's the day? ");

        if(day.equals("Monday")) { JOptionPane.showMessageDialog(null, "Welcome to Java club!");
        }
        else {JOptionPane.showMessageDialog(null, "Try again later!");
        }
        
    }
}

Answer 2

您不會在循環中更新name 。
代替：

String name = JOptionPane.showInputDialog("Enter your name... ");
        do{JOptionPane.showInputDialog( "YOUR NAME...");}
        while(name.equals(""));

做：

String name;
        do{
              name = JOptionPane.showInputDialog("Enter your name... ");
        while(name.equals(""));