java - void 对变量 main 无效？

Question

如何修复错误，Void 对变量 main 无效？我试着在网上查找这个，但找不到任何东西。另外，我对此有点陌生，所以请放轻松。我边走边学。

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;


public class Text extends JFrame
{


   JPanel jp = new JPanel();
   JLabel jl = new JLabel();
   JTextField jt = new JTextField("Month",30);
   JTextField jt2 = new JTextField("Date",30);
   JButton jb = new JButton("Enter");

   public Text()
   {
       public static void main (String[] args); {
          setTitle("Tutorial");
          setVisible(true);
          setSize(400, 200);
          setDefaultCloseOperation(EXIT_ON_CLOSE);

          jp.add(jt);
          jp.add(jt2);


          jt.addActionListener(new ActionListener()
          {
                 public void actionPerformed(ActionEvent e)
                 {
                       String input = jt.getText();
                       jl.setText(input); 
                 }
          });

          jp.add(jb);
          jb.addActionListener(new ActionListener()
          {
                  public void actionPerformed(ActionEvent e)
                  {


                         String input = jt.getText();
                         String input2 = jt2.getText();
                         jl.setText(input);
                         jl.setText(input2);
                         int day = Integer.parseInt(input2);
                            if ((input.equals("Test")) && (input2.equals(day >= 26)))//||(input2.equals("27")))))
                                JOptionPane.showMessageDialog(null, "" , "" ,JOptionPane.PLAIN_MESSAGE,aries);
                  }

          });


          add(jp);

   }

   }
}  

Answer 1

您已将main 方法放在 class Text 的构造函数中。它属于构造函数之外，与构造函数处于同一级别。将它移到构造函数之外。

public class Text extends JFrame
{


   JPanel jp = new JPanel();
   JLabel jl = new JLabel();
   JTextField jt = new JTextField("Month",30);
   JTextField jt2 = new JTextField("Date",30);
   JButton jb = new JButton("Enter");

   public static void main (String[] args); {
      setTitle("Tutorial");
      setVisible(true);
      setSize(400, 200);
      setDefaultCloseOperation(EXIT_ON_CLOSE);
      ...
   }

   public Text()
   {
      ...
   }
   ...
}