调用后java重绘方法不起作用

Question

我正在创建一个应用程序来实现一个算法，但在此之前，我需要让paint方法正常工作 我有一个按钮，单击它我调用测试方法，我从println获取输出“valuesset”，但是repaint方法没有得到执行

但在另一个简单的应用程序中也有同样的功能

任何帮助都会很好

顺便说一句，我是个电子人，所以我不太懂编程

This is the class for painting
`

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

public class Draw extends JPanel {

    private java.util.List<Rectangle> rectangles = 
                                new ArrayList<Rectangle>();

    public Draw() {
        setOpaque(true);
        setBackground(Color.WHITE);
        rectangles = new ArrayList<Rectangle>();
    }

    public void test(){
         rectangles.add(new Rectangle(10,10,10,10));
         rectangles.add(new Rectangle(20,20,10,10));
         rectangles.add(new Rectangle(30,30,10,10));
         rectangles.add(new Rectangle(40,40,10,10));
         rectangles.add(new Rectangle(50,50,10,10));       
         rectangles.add(new Rectangle(60,60,10,10));
         this.setValues(rectangles);
         System.out.println("in test class");
    }

    public void setValues(java.util.List<Rectangle> rectangles) {
        this.rectangles = rectangles;
        repaint();
        System.out.println("values set!!");
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawRect(5, 5, 100, 300);
        for (Rectangle rectangle : rectangles) {
            g.drawRect(rectangle.x, rectangle.y,rectangle.width, rectangle.height);
        }
        System.out.println("WORKING");
    }   
}

`

GUI类

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

public class Design extends JFrame{

    Draw Draw = new Draw();
    static HandlerClass handler = new HandlerClass();

        public void DisplayGUI(){

            JFrame frame = new JFrame("title");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            JPanel content = new JPanel();
            content.setLayout(new BorderLayout());
            frame.setContentPane(content);
.//Contains code that adds different buttons to Different panels
.
.
.
.           content.add(Draw, BorderLayout.CENTER);
            frame.setSize(775,600);
            frame.setVisible(true);

}

主课

import java.awt.EventQueue;
import javax.swing.JFrame;


public class Program extends JFrame{

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new Design().DisplayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }
}

处理程序类

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
public class HandlerClass implements ActionListener{

    private String string ="";
    ExampleOne ExampleOne = new ExampleOne();
    Draw draw = new Draw();

    public void actionPerformed(ActionEvent event){

        string = ((JButton) event.getSource()).getActionCommand();

        if(string == "Example 1"){
            ExampleOne.run();
        }
    }
}

class ExampleOne{
    Draw draw = new Draw();
    public void run(){
        System.out.println("in example one class"); 
        draw.test();
    }
}