油漆面板不正确的渲染

Question

以下是发生的事情：

我想制作一个非常基本的绘画程序来练习使用绘画方法，使用图形，使用工具栏等等。我一直在做很多关于如何做这些事情的阅读，而且我确定我在某个地方错过了一个重要的代码行，因为paintpanel本身正在渲染一个不是这样的JMenu。应该在那里。我有一个使用actionListeners设置的JMenu，但是作为额外渲染的那个没有做任何事情而且无法与之交互。这是一张图片：

正如您在下图中看到的那样，我可以在菜单上绘画，但它仍然没有反应。另外，这次你可以看到程序中前一个窗口的radom按钮由于某种原因被添加。

此按钮来自以下位置：

我对如何解决这个问题感到很遗憾，所以这里是相关类的代码：

这是绘画的面板。     包画家;

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

import javax.swing.JPanel;
import javax.swing.event.MouseInputListener;

@SuppressWarnings("serial")
public class PaintPanel extends JPanel implements MouseInputListener
{
    //These two values will be used to determine where the mouse is and thus where to paint...stuff...
    public int xCoordinate, yCoordinate = -10;

    static Color currentColor = Color.black;

    public PaintPanel()
    {
        //These two methods simply attaches the mouse listener methods listed below to the actual panel.
        addMouseListener(this);
        addMouseMotionListener(this);
    }
    //This method is an overwritten version of the default paint method.  It's job is to render custom graphics
    //objects on the screen.  The Graphics g argument is the item responsible for doing the actual rendering.
    @Override
    public void paintComponent(Graphics g)
    {
        // super.paintComponent(g);
         g.setColor(currentColor);
         g.fillRect(xCoordinate, yCoordinate, 10, 10);
    }

    @Override
    //This method, added because of the MouseInputListener implementation, is used when a user clicks the left mouse button.
    public void mouseClicked(MouseEvent e) 
    {
        xCoordinate = e.getX();
        yCoordinate = e.getY();
        repaint();
    }
    @Override
    public void mouseEntered(MouseEvent arg0) 
    {
        // TODO Auto-generated method stub

    }
    @Override
    public void mouseExited(MouseEvent arg0)
    {
        // TODO Auto-generated method stub

    }

    @Override
    public void mousePressed(MouseEvent arg0) 
    {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseReleased(MouseEvent arg0) 
    {
        // TODO Auto-generated method stub

    }

    @Override
    //This method, added because of the MouseInputListener implementation, is used when a user presses and holds the
    //left mouse button while moving the mouse.
    public void mouseDragged(MouseEvent e) 
    {   
        xCoordinate = e.getX();
        yCoordinate = e.getY();
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent arg0) 
    {
        // TODO Auto-generated method stub

    }
    public static void changeColor(Color color)
    {
        currentColor = color;
    }
}

这是在PaintPanel，菜单和后来的其他按钮等中添加的主类。

package painter;

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JMenuBar;
import javax.swing.JPanel;

import painter.menu.FileMenu;
import painter.menu.ToolsMenu;

@SuppressWarnings("serial")
//This class will do the job of bringing together all the various sub-classes and rendering everything.
public class MainPainterGUI extends JFrame
{
    private JPanel menuPanel;

    private JMenuBar menuBar;

    //These values are going to be used to set an initial window size.
    private final short WINDOW_HEIGHT = 1000;
    private final short WINDOW_WIDTH = 1000;

    //This constructor will do the actual creation of the window.
    public MainPainterGUI()
    {
        //This does the same thing that setTitle does.
        super("Painter");
        //setTitle("Painter");

        //This method will set what the window is supposed to do when the red x is clicked.
        //Technically, the value passed is an integer.
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        //Obviously this method sets the initial size of the window.  It can be changed by the user however.
        setSize(WINDOW_WIDTH,WINDOW_HEIGHT);

        //This method sets the center of the window relative to whatever is passed.  In this case, null makes
        //the window appear in the center of the desktop regardless of the size.
        setLocationRelativeTo(null);

        menuPanel = new JPanel();

        menuBar = new JMenuBar();

        menuBar.add(new FileMenu());
        menuBar.add(new ToolsMenu());

        menuPanel.add(menuBar);

        //The add method simply attaches a component to whatever is calling, like a frame or another panel.
        //The BorderLayout is needed to use the draggable toolbar.
        add(new PaintPanel(), BorderLayout.CENTER);
        add(menuPanel, BorderLayout.NORTH);

        //This will allow the window to be seen.  Make sure this method is last, as if 
        //a component is created afterwards it may not be visible.
        setVisible(true);
    }
}

这两个类应该是唯一与当前问题相关的类，但是如果需要其他类，请告诉我。我只是不想用无用的信息弄乱帖子。

现在，我已经尝试过了：

正如您在PaintPanel类中看到的，我添加了一个super.paintComponent（g）;方法调用。然而，虽然这完全解决了我的问题，但它一次只绘制一个黑色方块。我会想象，因为它用绘画调用覆盖了面板，然后每次调用重绘时绘制正方形。

这是添加了super.paintComponent（g）的照片：

我不确定这是否重要，但我使用的是Windows 10。

感谢您提供的任何帮助。

Answer 1

我认为您需要致电.repaint()以减少您的用户界面。