Question

JRE版本1.7更新3

预期行为

当我运行该程序时，它按预期工作，一切顺利。当我点击STOP JButton时动画停止，同一JButton上的文字变为START。现在当我点击BALL COLOUR JButton时，BALL的颜色以及BALL COLOUR JBUTTON的颜色也会发生变化BALL的。{如果我按原样运行我的应用程序而不调整大小，则整个行为都有效。

意外行为

但是当我RESIZE我的JFrame时，通过拉Right Side，就会显示我的应用程序的意外行为，即我按STOP { {1}}然后点击JButton按钮，之前点击的文字已更改为BALL COLOUR的{{1}}上的文字将再次更改为JButton。以及START STOP的颜色将保持不变或将转为BALL COLOUR，此时应将其更改为球的颜色。我附上照片了解更多信息。但是如果你试图将它重新调整到原来的大小或更接近它，那么事情就会恢复正常。为什么会这样？任何想法或线索都将非常感激。

正如我的应用程序以预期行为运行，如上所述：

Expected Behaviour

此处意外行为

Unexpected Behaviour

BOTTOM-LINE：

为什么应用程序在JButton处照常运行，而在BLUE处拖动它BEGINNING，但如果你将它带到原始尺寸或更接近它，事情恢复正常，它按预期工作？

所以考虑到这个场景，我在程序中做错了什么。或者恰恰是这种情况，我应该使用RESIZED，或者这是RIGHT SIDE的问题，还是隐藏与SwingWorker相关的问题。请注意： - ）

这是我正在使用的代码，我把它降到最低限度，因为我想要证明我的问题：

Layout

**最新编辑：**

LATEST

Answer 1

你的非常好的例子的问题可能与平台有关，但我可以提供一些观察：

您没有添加或删除组件，因此您不需要revalidate()。
由于背景颜色是按钮的绑定属性，因此您无需后续调用repaint()。
您需要repaint()中的DrawingArea，但您可能需要尝试添加属性更改支持，如建议的here。
Color.white不能是brighter()而Color.black不能是darker(); Color.darkGray.darker()为Color.black()。
下面的变体使用Queue<Color>来简化颜色的更改。

screen capture

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

/** @see https://stackoverflow.com/q/9849950/230513 */
public class BallAnimation {

    private int x;
    private int y;
    private boolean positiveX;
    private boolean positiveY;
    private boolean isTimerRunning;
    private int speedValue;
    private int diameter;
    private DrawingArea drawingArea;
    private Timer timer;
    private Queue<Color> clut = new LinkedList<Color>(Arrays.asList(
        Color.BLUE.darker(),
        Color.MAGENTA.darker(),
        Color.BLACK,
        Color.RED.darker(),
        Color.PINK,
        Color.CYAN.darker(),
        Color.DARK_GRAY,
        Color.YELLOW.darker(),
        Color.GREEN.darker()));
    private Color backgroundColour;
    private Color foregroundColour;
    private ActionListener timerAction = new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent ae) {
            x = getX();
            y = getY();
            drawingArea.setXYColourValues(x, y, backgroundColour, foregroundColour);
        }
    };
    private JPanel buttonPanel;
    private JButton startStopButton;
    private JButton speedIncButton;
    private JButton speedDecButton;
    private JButton resetButton;
    private JButton colourButton;
    private JButton exitButton;
    private ComponentAdapter componentAdapter = new ComponentAdapter() {

        @Override
        public void componentResized(ComponentEvent ce) {
            timer.restart();
            startStopButton.setText("Stop");
            isTimerRunning = true;
        }
    };

    public BallAnimation() {
        x = y = 0;
        positiveX = positiveY = true;
        speedValue = 1;
        isTimerRunning = false;
        diameter = 50;
        backgroundColour = Color.white;
        foregroundColour = clut.peek();
        timer = new Timer(10, timerAction);
    }

    private void createAndDisplayGUI() {
        JFrame frame = new JFrame("Ball Animation");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);

        drawingArea = new DrawingArea(x, y, backgroundColour, foregroundColour, diameter);
        drawingArea.addComponentListener(componentAdapter);

        frame.add(makeButtonPanel(), BorderLayout.LINE_END);
        frame.add(drawingArea, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
    }

    private JPanel makeButtonPanel() {
        buttonPanel = new JPanel(new GridLayout(0, 1));
        buttonPanel.setBorder(BorderFactory.createLineBorder(Color.darkGray, 5));

        startStopButton = new JButton("Start");
        startStopButton.setOpaque(true);
        startStopButton.setForeground(Color.white);
        startStopButton.setBackground(Color.green.darker());
        startStopButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent ae) {
                if (!isTimerRunning) {
                    startStopButton.setText("Stop");
                    timer.start();
                    isTimerRunning = true;
                } else if (isTimerRunning) {
                    startStopButton.setText("Start");
                    timer.stop();
                    isTimerRunning = false;
                }
            }
        });
        startStopButton.setBorder(BorderFactory.createLineBorder(Color.gray, 4));
        buttonPanel.add(startStopButton);

        colourButton = new JButton("Change Color");
        colourButton.setOpaque(true);
        colourButton.setForeground(Color.white);
        colourButton.setBackground(clut.peek());
        colourButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent ae) {
                //timer.restart();
                clut.add(clut.remove());
                foregroundColour = clut.peek();
                drawingArea.setXYColourValues(x, y, backgroundColour, foregroundColour);
                colourButton.setBackground(foregroundColour);
            }
        });
        colourButton.setBorder(BorderFactory.createLineBorder(Color.gray, 4));
        buttonPanel.add(colourButton);

        exitButton = new JButton("Exit");
        exitButton.setBackground(Color.red);
        exitButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent ae) {
                timer.stop();
                System.exit(0);
            }
        });
        exitButton.setBorder(BorderFactory.createLineBorder(Color.red.darker(), 4));
        buttonPanel.add(exitButton);

        return buttonPanel;
    }

    private int getX() {
        if (x < 0) {
            positiveX = true;
        } else if (x >= drawingArea.getWidth() - diameter) {
            positiveX = false;
        }
        return (calculateX());
    }

    private int calculateX() {
        if (positiveX) {
            return (x += speedValue);
        } else {
            return (x -= speedValue);
        }
    }

    private int getY() {
        if (y < 0) {
            positiveY = true;
        } else if (y >= drawingArea.getHeight() - diameter) {
            positiveY = false;
        }
        return (calculateY());
    }

    private int calculateY() {
        if (positiveY) {
            return (y += speedValue);
        } else {
            return (y -= speedValue);
        }
    }

    public static void main(String... args) {
        Runnable runnable = new Runnable() {

            @Override
            public void run() {
                new BallAnimation().createAndDisplayGUI();
            }
        };
        SwingUtilities.invokeLater(runnable);
    }
}

class DrawingArea extends JComponent {

    private int x;
    private int y;
    private int ballDiameter;
    private Color backgroundColor;
    private Color foregroundColor;

    public DrawingArea(int x, int y, Color bColor, Color fColor, int dia) {
        this.x = x;
        this.y = y;
        ballDiameter = dia;
        backgroundColor = bColor;
        foregroundColor = fColor;
        setBorder(BorderFactory.createLineBorder(Color.DARK_GRAY, 5));
    }

    public void setXYColourValues(int x, int y, Color bColor, Color fColor) {
        this.x = x;
        this.y = y;
        backgroundColor = bColor;
        foregroundColor = fColor;
        repaint();
    }

    @Override
    public Dimension getPreferredSize() {
        return (new Dimension(500, 400));
    }

    @Override
    public void paintComponent(Graphics g) {
        g.setColor(backgroundColor);
        g.fillRect(0, 0, getWidth(), getHeight());
        g.setColor(foregroundColor);
        g.fillOval(x, y, ballDiameter, ballDiameter);
    }
}

Answer 2

似乎BorderLayout.LINE_END内容有问题，只有当buttonPanel放在LINE_END上时，我才会收到不良后果。我试图只使用一个JButton而不是三个作为最新的衡量标准来解决问题。现在问题如图所示：

LINE_END

已通过将JButton小组的位置更改为LINE_START或使用JRE version 1.6 update 31进行整理，如下图所示：

LINE_START

以下是此示例使用的代码：

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class BallAnimation
{
    private int x;
    private int y;
    private boolean positiveX;
    private boolean positiveY;
    private boolean isTimerRunning; 
    private int speedValue;
    private int diameter; 
    private DrawingArea drawingArea;    
    private Timer timer;
    private int colourCounter;
     Color[] colours = {
                            Color.BLUE.darker(),
                            Color.MAGENTA.darker(),
                            Color.BLACK.darker(),
                            Color.RED.darker(),
                            Color.PINK.darker(),
                            Color.CYAN.darker(),
                            Color.DARK_GRAY.darker(),
                            Color.YELLOW.darker(),
                            Color.GREEN.darker()
                       };

    private Color backgroundColour;
    private Color foregroundColour; 

    private ActionListener timerAction = new ActionListener()
    {
        public void actionPerformed(ActionEvent ae)
        {
            x = getX();
            y = getY();
            drawingArea.setXYColourValues(x, y, backgroundColour
                                        , foregroundColour);
        }       
    };

    private JPanel buttonPanel;
    private JButton startStopButton;
    private JButton speedIncButton;
    private JButton speedDecButton;
    private JButton resetButton;
    private JButton colourButton;
    private JButton exitButton;

    private ComponentAdapter componentAdapter = new ComponentAdapter()
    {
        public void componentResized(ComponentEvent ce)
        {
            timer.restart();
        }
    };  

    public BallAnimation()
    {
        x = y = 0;
        positiveX = positiveY = true;
        speedValue = 1;
        colourCounter = 0;
        isTimerRunning = false;
        diameter = 50;
        backgroundColour = Color.WHITE.brighter();
        foregroundColour = colours[colourCounter];
        timer = new Timer(10, timerAction);
    }

    private void createAndDisplayGUI()
    {
        JFrame frame = new JFrame("Ball Animation");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);

        drawingArea = new DrawingArea(x, y
                            , backgroundColour, foregroundColour, diameter);
        drawingArea.addComponentListener(componentAdapter);

        frame.add(makeButtonPanel(), BorderLayout.LINE_START);
        frame.add(drawingArea, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);     
    }

    private JPanel makeButtonPanel()
    {
        buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(0, 1));
        buttonPanel.setBorder(BorderFactory.createLineBorder(
                                    Color.DARK_GRAY, 5, true));

        colourButton = new JButton("BALL COLOUR");
        colourButton.setOpaque(true);
        colourButton.setBackground(colours[colourCounter]);
        colourButton.setForeground(Color.WHITE);
        colourButton.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                System.out.println("COLOUR JButton Clicked!");
                if (timer.isRunning())
                    timer.stop();
                colourCounter++;
                if (colourCounter == 9)
                    colourCounter = 0;
                foregroundColour = colours[colourCounter];
                drawingArea.setXYColourValues(x, y, backgroundColour
                                                    , foregroundColour);
                colourButton.setBackground(foregroundColour);
                if (!timer.isRunning())
                    timer.start();
            }
        });
        colourButton.setBorder(BorderFactory.createLineBorder(
                                    Color.WHITE, 2, true));
        buttonPanel.add(colourButton);

        return buttonPanel;
    }

    private int getX()
    {
        if (x < 0)
            positiveX = true;
        else if (x >= drawingArea.getWidth() - diameter)
            positiveX = false;
        return (calculateX());
    }

    private int calculateX()
    {
        if (positiveX)
            return (x += speedValue);
        else
            return (x -= speedValue);
    }

    private int getY()
    {
        if (y < 0)
            positiveY = true;
        else if (y >= drawingArea.getHeight() - diameter)
            positiveY = false;
        return (calculateY());
    }

    private int calculateY()
    {
        if (positiveY)
            return (y += speedValue);
        else 
            return (y -= speedValue);
    }

    public static void main(String... args)
    {
        Runnable runnable = new Runnable()
        {
            public void run()
            {
                new BallAnimation().createAndDisplayGUI();
            }
        };
        SwingUtilities.invokeLater(runnable);
    }
}

class DrawingArea extends JComponent
{
    private int x;
    private int y;
    private int ballDiameter;
    private Color backgroundColor;
    private Color foregroundColor;

    public DrawingArea(int x, int y
                , Color bColor, Color fColor, int dia)
    {
        this.x = x;
        this.y = y;
        ballDiameter = dia;
        backgroundColor = bColor;
        foregroundColor = fColor;
        setBorder(BorderFactory.createLineBorder(
                        Color.DARK_GRAY.darker(), 5, true));
    }

    public void setXYColourValues(int x, int y
                            , Color bColor, Color fColor)
    {
        this.x = x;
        this.y = y;
        backgroundColor = bColor;
        foregroundColor = fColor;
        repaint();
    }

    public Dimension getPreferredSize()
    {
        return (new Dimension(500, 400));
    }

    public void paintComponent(Graphics g)
    {
        g.setColor(backgroundColor);
        g.fillRect(0, 0, getWidth(), getHeight());
        g.setColor(foregroundColor);
        g.fillOval(x, y, ballDiameter, ballDiameter);
    }
}

Answer 3

maybe will help you with two parts of，我认为Graphics/2D被指定专门使用Swing Timer，

Answer 4

我不确定我是否为您的系统找到了解决方案，但是将代码调整为

colourButton = new JButton( "BALL COLOUR" );
colourButton.setOpaque( true );
colourButton.setBackground( colours[ colourCounter ] );
colourButton.setForeground( Color.WHITE );

适用于我的系统（OS X with Java 1.7）。请注意所需的setOpaque调用，以便setBackground调用具有该方法的javadoc中所述的任何效果：

设置此组件的背景颜色。仅当组件不透明时才使用背景颜色

在OS X上，没有setOpaque调用，您的代码在调整大小之前甚至不起作用

布局似乎有些问题，JButton在调整窗口大小时显示出意外行为

4 个答案: