Java，swing，面板和文本区域，不会改变颜色，可能引用错误

Question

我试图制作一个框架，在面板中控制操作，并在鼠标在控制面板中执行某些操作后创建一个 TextArea 以某种方式使用react。不知道为什么它不想在控制面板(北面板)内按下鼠标时更改 TextArea 的状态(背景颜色)。 我猜想 MouseEventHandler 类中对 textArea 对象的引用有问题，但不知道如何修复它。我用 getSource() 方法搜索，看来我是对的，但不知道如何使它正确。

主要

package MainPackage;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.WindowConstants;

public class Main {

public static void main(String[] args) {

    EventQueue.invokeLater(new Runnable() {
        public void run() {


            // Draw a frame
            final DrawFrame frame = new DrawFrame(500, 500);
            // Add yes-no confirmation of closing the application
            frame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
            frame.addWindowListener(new WindowAdapter() {
                public void windowClosing(WindowEvent e) {
                    int confirmInt = JOptionPane.showOptionDialog(null,
                            "Are you sure?", "Exit confirmation",
                            JOptionPane.YES_NO_OPTION,
                            JOptionPane.QUESTION_MESSAGE, null, null, null);
                    if (confirmInt == JOptionPane.YES_OPTION) {
                        frame.dispose();
                    }
                }

            });

            // Create a textField
            JTextArea textArea= new JTextArea();

            //Set textField's variables
            textArea.setBackground(Color.RED);
            textArea.setPreferredSize(new Dimension(500, 300));
            frame.add(textArea, BorderLayout.PAGE_END);

            // Add a drawPanel
            JPanel drawPanel = new JPanel(new BorderLayout());

            //Set drawPanel's variables
            drawPanel.setBackground(Color.CYAN);
            drawPanel.setPreferredSize(new Dimension(500, 200));
            drawPanel.addMouseListener(new MouseEventHandler(textArea));
            frame.add(drawPanel, BorderLayout.PAGE_START);

            //Set frame visible
            frame.setVisible(true);
        }
    });




}




}

绘图框

package MainPackage;

import javax.swing.JFrame;

public class DrawFrame extends JFrame {

private static final long serialVersionUID = 8914767267085394262L;


public DrawFrame(int width, int height) {
    setSize(width, height);
    setTitle("MouseTest");

}

}

鼠标操作 包主包；

import java.awt.Color;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.JTextArea;

class MouseEventHandler extends Main implements MouseListener

{   private JTextArea textArea;

public MouseEventHandler(JTextArea textArea)
{
    textArea = this.textArea;
}

public void mouseClicked(MouseEvent event) {

    textArea.setBackground(Color.BLUE);
}


public void mousePressed(MouseEvent event) {
}

public void mouseReleased(MouseEvent event) {
}

public void mouseEntered(MouseEvent event) {
}

public void mouseExited(MouseEvent event) {
}
}

Answer 1

查看您的 MouseEventHandler 构造函数。应该是:

public MouseEventHandler(JTextArea textArea) {
    this.textArea = textArea;
}

比它有效。面板是蓝色的。