import javax.swing.*;
import javax.awt.event.*;
import javax.awt.*;

public class Test02 extends JFrame {
   
    //窗口的创建方法
    public void CreateFrame(){
        JPanel jp1=new JPanel();
        JPanel jp2=new JPanel();
        JPanel jp3=new JPanel();
        
        JLabel jl1=new JLabel("用户名：");
        JLabel jl2=new JLabel("密码：");
        
        JButton jb1=new JButton("登录");
        JButton jb2=new JButton("重置");
        
        JTextField jtf=new JTextField(10);
        JPasswordField jpf=new JPasswordField(10);
        
        this.setLayout(new GridLayout(3,1));
        
        jp1.add(jl1);
        jp1.add(jtf);
        jp2.add(jl2);
        jp2.add(jpf);
        jp3.add(jb1);
        jp3.add(jb2);
        this.add(jp1);
        this.add(jp2);
        this.add(jp3);
        

        this.setTitle("示例窗口");
        //this.pack();
        this.setSize(800,600);
        this.setLocationRelativeTo(null);
        this.setVisible(true);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
   
    public static void main(String[] args){
        Test02 frame1=new Test02();
        frame1.CreateFrame();
    }

}
为什么会提示错误Exception in thread "main" java.lang.Error: Unresolved compilation problem:
    GridLayout cannot be resolved to a type

原来是包导错了