使用actionListener從單獨的類顯示對象

Question

我有一堂課，創造一個笑臉。 當我在下面運行代碼時，一切正常，並創建了9個笑臉對象並將其顯示在網格布局中。 但是，我想采用循環9次並創建/顯示9個表情符號的代碼塊，並在單擊creatSmiley按鈕時調用它。

但是，當我將這段代碼移到actionEvent上時，運行代碼並按下按鈕不會發生任何事情。

從其創建對象的笑臉類擴展了jpanel並使用paint方法創建了笑臉。

有小費嗎？

      public class SmileyGrid extends JFrame implements ActionListener
{

private JPanel buttonPanel, panel, facePanel;
private JButton pumpkinButton, smileyButton;



public static void main(String[] args)
{
    SmileyGrid myGrid = new SmileyGrid(); 
    myGrid.setSize(700, 700);
    myGrid.setLayout(new BorderLayout());
    myGrid.createGUI();
    myGrid.setVisible(true);

}

public SmileyGrid()
{

}

private void createGUI()
{
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    Container window = getContentPane();
    window.setLayout (new BorderLayout());

    facePanel = new JPanel();
    facePanel.setLayout(new GridLayout(3,3));
    facePanel.setPreferredSize(new Dimension(700, 700));
    add(facePanel);

    smileyButton = new JButton("Create Smiley");
    pumpkinButton = new JButton("Create Pumpkin");

    smileyButton.addActionListener(this);


    buttonPanel = new JPanel();
    buttonPanel.setBackground(Color.white);
    add (buttonPanel, BorderLayout.SOUTH);

    buttonPanel.add(smileyButton);
    buttonPanel.add(pumpkinButton);


    for(int i=0;i<9;i++)
    {
        Random r = new Random();
        Color color1=new Color(r.nextInt(256),r.nextInt(256),r.nextInt(256));
        Color color2=new Color(r.nextInt(256),r.nextInt(256),r.nextInt(256));
        Color color3=new Color(r.nextInt(256),r.nextInt(256),r.nextInt(256));
        Color color4=new Color(r.nextInt(256),r.nextInt(256),r.nextInt(256));

        Smiley mySmiley = new Smiley(color1, color2, color3, color4);

        facePanel.add(mySmiley);
    }

}
public void actionPerformed(ActionEvent ae)
{  

}
}

Answer 1

因此，我修改了您的基本代碼，因為您沒有包括Smiley類，而是將for-loop移至ActionListener的actionPerformed方法，並在創建一堆新的“”后在facePanel上調用revalidate和repaint假笑臉”對我來說效果很好

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class SmileyGrid extends JFrame implements ActionListener {

    private JPanel buttonPanel, panel, facePanel;
    private JButton pumpkinButton, smileyButton;

    public static void main(String[] args) {
        SmileyGrid myGrid = new SmileyGrid();
        myGrid.setSize(700, 700);
        myGrid.setLayout(new BorderLayout());
        myGrid.createGUI();
        myGrid.setVisible(true);

    }

    public SmileyGrid() {

    }

    private void createGUI() {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        Container window = getContentPane();
        window.setLayout(new BorderLayout());

        facePanel = new JPanel();
        facePanel.setLayout(new GridLayout(3, 3));
        facePanel.setPreferredSize(new Dimension(700, 700));
        add(facePanel);

        smileyButton = new JButton("Create Smiley");
        pumpkinButton = new JButton("Create Pumpkin");

        smileyButton.addActionListener(this);

        buttonPanel = new JPanel();
        buttonPanel.setBackground(Color.white);
        add(buttonPanel, BorderLayout.SOUTH);

        buttonPanel.add(smileyButton);
        buttonPanel.add(pumpkinButton);

//        for (int i = 0; i < 9; i++) {
//            Random r = new Random();
//            Color color1 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));
//            Color color2 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));
//            Color color3 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));
//            Color color4 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));
//
//            Smiley mySmiley = new Smiley(color1, color2, color3, color4);
//
//            facePanel.add(mySmiley);
//        }

    }

    @Override
    public void actionPerformed(ActionEvent ae) {

        for (int i = 0; i < 9; i++) {
            Random r = new Random();
            Color color1 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));
            Color color2 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));
            Color color3 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));
            Color color4 = new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256));

//            Smiley mySmiley = new Smiley(color1, color2, color3, color4);
            JPanel mySmiley = new JPanel() {
                @Override
                public Dimension getPreferredSize() {
                    return new Dimension(20, 20);
                }                
            };
            mySmiley.setBackground(color1);

            facePanel.add(mySmiley);
        }
        facePanel.revalidate();
        facePanel.repaint();

    }
}

如果您還有其他問題，可能與您的Smiley班有關