java - Swing - drawString 移动动画失败

Question

我正在尝试在Java swing上制作一个小动画，这应该将drawString的字符串向左移动一点(到中心)，但是，每当我尝试这样做时，程序都会慢慢打开并跳转到它最终应该着陆的地方，所以看起来，没有动画发生。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.border.Border;

public class IntroPanel extends JPanel {

private int x = 300;
private JButton exitButton, startButton;
private JPanel buttonsPanel;

public IntroPanel()
{
    setPreferredSize( new Dimension( 300, 150));
    setLayout( new BorderLayout());

    buttonsPanel = new JPanel();
    exitButton = new JButton( "Exit" );
    startButton = new JButton( "Start" );

    exitButton.addActionListener( new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.exit(0);
        }
    });

    startButton.addActionListener( new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            /**
             * TODO GOES TO MAIN PANEL
             */
        }
    });

    setBackground( new Color( 250, 250, 250) );
    startButton.setPreferredSize( new Dimension(70, 40) );
    exitButton.setPreferredSize( new Dimension(70, 40) );
    Border padding = BorderFactory.createEmptyBorder(0, 0, 25, 0);
    setBorder(padding);
    buttonsPanel.setBackground( new Color( 250, 250, 250));
    buttonsPanel.add(startButton);
    buttonsPanel.add(exitButton);
    add(buttonsPanel, BorderLayout.SOUTH);
    animate();
}

public void animate()
{
    for( int i = 1; i < 211; i++ )
    {
        x--;

        repaint();

        try
        {
            Thread.sleep(10);
        }
        catch(InterruptedException ex) { }
    }
}

public void paintComponent( Graphics page )
{
    Graphics2D gra = (Graphics2D) page;

    gra.setFont( new Font( "Philosopher-BoldItalic", Font.ITALIC | Font.BOLD, 50 ) );

    Color start = new Color( 50, 50, 50 );
    Color end = new Color( 250, 250, 250 );

    GradientPaint gradient = 
            new GradientPaint( 120, 100, start, 270, 270, end);

    gra.setRenderingHint( RenderingHints.KEY_TEXT_ANTIALIASING, 
            RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
    gra.setPaint( gradient );

    gra.drawString("Geometrica", x, 100);
 }
}

主要方法:

    public class Main {

      public static void main(String[] args) {   
        JFrame frame = new JFrame( "Geometrica" );
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.setSize(420, 250);
        frame.setBackground( new Color(250, 250, 250) );

        frame.setLocationRelativeTo(null);
        frame.getContentPane().add( new IntroPanel() );
        frame.setVisible(true);
       }
     }

谢谢!

Answer 1

在框架从对象外部可见后调用 animate 方法。

此外，您还需要在 animate 方法中调用 super.paintComponent(page); (如 Javadoc 中所述)，然后您将获得所需的结果。主要:

public class Main {

      public static void main(String[] args) {   
        JFrame frame = new JFrame( "Geometrica" );
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.setSize(420, 250);
        frame.setBackground( new Color(250, 250, 250) );

        frame.setLocationRelativeTo(null);
        IntroPanel p=new IntroPanel();
        frame.getContentPane().add(p);
        frame.setVisible(true);
        p.animate();        

       }
}

简介面板:

public class IntroPanel extends JPanel {

private int x = 300;
private JButton exitButton, startButton;
private JPanel buttonsPanel;

public IntroPanel()
{
    setPreferredSize( new Dimension( 300, 150));
    setLayout( new BorderLayout());

    buttonsPanel = new JPanel();
    exitButton = new JButton( "Exit" );
    startButton = new JButton( "Start" );

    exitButton.addActionListener( new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.exit(0);
        }
    });

    startButton.addActionListener( new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            /**
             * TODO GOES TO MAIN PANEL
             */
        }
    });

    setBackground( new Color( 250, 250, 250) );
    startButton.setPreferredSize( new Dimension(70, 40) );
    exitButton.setPreferredSize( new Dimension(70, 40) );
    Border padding = BorderFactory.createEmptyBorder(0, 0, 25, 0);
    setBorder(padding);
    buttonsPanel.setBackground( new Color( 250, 250, 250));
    buttonsPanel.add(startButton);
    buttonsPanel.add(exitButton);
    add(buttonsPanel, BorderLayout.SOUTH);
}

public void animate()
{
    super.paintComponent(page);
    for( int i = 1; i < 211; i++ )
    {
        x--;

        repaint();

        try
        {
            Thread.sleep(10);
        }
        catch(InterruptedException ex) { }
    }
}

public void paintComponent( Graphics page )
{
    Graphics2D gra = (Graphics2D) page;

    gra.setFont( new Font( "Philosopher-BoldItalic", Font.ITALIC | Font.BOLD, 50 ) );

    Color start = new Color( 50, 50, 50 );
    Color end = new Color( 250, 250, 250 );

    GradientPaint gradient = 
            new GradientPaint( 120, 100, start, 270, 270, end);

    gra.setRenderingHint( RenderingHints.KEY_TEXT_ANTIALIASING, 
            RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
    gra.setPaint( gradient );

    gra.drawString("Geometrica", x, 100);
 }
}