油漆function不在Java Swing中调用

Question

My purpose - to create a board with lines, using Java Swing.

After I made a board and added color to it, I tried to produce lines. To do this, I inherit from JPanel and added paintComponent method. But when I run the application, the method is not called.

I added default constructor with super(); I also added to the called constructor super();

I still cannot make the paint method or the paintComponent method to get run;

I tried all of the following posts: Java Swing paint() not working Insert Button in JPanel

public class Main {
    public static void main(String[] args) {
        Board board = new Board(295, 295, "Go board");
    }
}

import java.awt.*;
import javax.swing.*;


public class Board extends JPanel{
     private int width;
     private int height;
     private String title;
     private JFrame JFrame;
     
     
     public int getWidth() {
        return width;
    }

    public void setWidth(int width) {
        this.width = width;
    }

    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public JFrame getJFrame() {
        return JFrame;
    }

    public void setJFrame(JFrame JFrame) {
        this.JFrame = JFrame;
    }

    public Board(int width, int height, String title){
        super();
         this.width = width;
         this.height = height;
         this.title = title;
         this.initBoard();
         
     }
    
    public Board(){
        super();
    }
    
     public void initBoard(){
           JFrame f = new JFrame(this.getTitle());
           f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           f.getContentPane().setBackground(Color.getHSBColor(25, 75, 47));
           f.setSize(this.getWidth(), this.getHeight());
           f.setLocation(550, 25);
           f.setVisible(true);
            this.setJFrame(f);
     }
         
     public void paint(Graphics g) {
         g.drawLine(10, 10, 250, 10);
         System.out.println("Test paint");
     }
     
     public void paintComponent(Graphics g) {
         g.drawLine(10, 10, 250, 10);
         System.out.println("Test paintComponent");
     }
         
}    

Answer 1

You never have called your initBoard which contains JFrame (which is bad design). Also you must add your panel to that frame with jframe.add(this);

It would be better to have your frame alone, and add your component to it like this

public static void main(){
    JFrame f=new JFrame();
    ///set all the dimensions and other stuff of the frame
    f.setLayout(new BorderLayout);
    f.add(new Board(295, 295, "Go board"),BorderLayour.CENTER);
    f.setVisible();
}