为什么这个动作不抽象？

我很难理解为什么类中的一个Actions是抽象的而另一个类中的Action不是。

源代码1 :(编译时出错： https ： //gyazo.com/cd3c21a8562589451814903febaf89fe ）

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Play extends JFrame{ Engine drawPanel = new Engine(); private int x = 0; private int y = 0; public int getX(){ return x; } public int getY(){ return y; } public Play(){ Action rightAction = new AbstractAction(){ public void actionPreformed(ActionEvent e){ x+=10; drawPanel.repaint(); } }; Action leftAction = new AbstractAction(){ public void actionPreformed(ActionEvent e){ x-=10; drawPanel.repaint(); } }; InputMap inputMap = drawPanel.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW); ActionMap actionMap = drawPanel.getActionMap(); inputMap.put(KeyStroke.getKeyStroke("RIGHT"), "rightAction"); actionMap.put("rightAction", rightAction); inputMap.put(KeyStroke.getKeyStroke("LEFT"), "leftAction"); actionMap.put("leftAction", leftAction); add(drawPanel); pack(); setDefaultCloseOperation(EXIT_ON_CLOSE); setSize(640, 480); setTitle("Game"); setLocationRelativeTo(null); setVisible(true); } public static void main(String[] args){ EventQueue.invokeLater(new Runnable(){ @Override public void run(){ new Play(); } }); } } 

源代码2 :(编译得很好的代码）

 import java.awt.*; import java.awt.event.*; import javax.swing.*; public class KeyBidings extends JFrame { int x = 0; int y = 0; DrawPanel drawPanel = new DrawPanel(); public KeyBidings(){ Action rightAction = new AbstractAction(){ public void actionPerformed(ActionEvent e) { x +=10; drawPanel.repaint(); } }; InputMap inputMap = drawPanel.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW); ActionMap actionMap = drawPanel.getActionMap(); inputMap.put(KeyStroke.getKeyStroke("RIGHT"), "rightAction"); actionMap.put("rightAction", rightAction); add(drawPanel); pack(); setDefaultCloseOperation(EXIT_ON_CLOSE); setLocationRelativeTo(null); setVisible(true); } private class DrawPanel extends JPanel { protected void paintComponent(Graphics g) { super.paintComponent(g); g.setColor(Color.GRAY); g.fillRect(0, 0, getWidth(), getHeight()); g.setColor(Color.GREEN); g.fillRect(x, y, 50, 50); } public Dimension getPreferredSize() { return new Dimension(400, 200); } } public static void main(String[] args) { EventQueue.invokeLater(new Runnable(){ public void run(){ new KeyBidings(); } }); } } 

Answer 1

因为在第一个示例中您输入错误：

 actionPreformed 

应该是

 actionPerformed