一、当java的命名与导入的类或模块起冲突的话，会导致很多异常问题出现。
二、代码(注意下方截图）
MainMethod.java: package cn.lrt.program; import java.awt.*; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; class MainMethod extends Frame { KeyListener keyListener = new KeyListener(); public void launchedFrame() { this.setTitle("我是一个测试"); this.setVisible(true); this.setSize(300,300); this.setLocation(300,300); this.addWindowListener(new WindowAdapter(){ @Override public void windowClosing(WindowEvent e) { System.exit(0); } }); this.addKeyListener(new KeyListener()); } public static void main(String[] args) { MainMethod method = new MainMethod(); method.launchedFrame(); } class KeyListener extends KeyAdapter { public void keyPressed(KeyEvent e) { keyListener.addDirection(e); } public void keyReleased(KeyEvent e) { } } } KeyListener.java package cn.lrt.program; import java.awt.*; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; class MainMethod extends Frame { KeyListener keyListener = new KeyListener(); public void launchedFrame() { this.setTitle("我是一个测试"); this.setVisible(true); this.setSize(300,300); this.setLocation(300,300); this.addWindowListener(new WindowAdapter(){ @Override public void windowClosing(WindowEvent e) { System.exit(0); } }); this.addKeyListener(new KeyListener()); } public static void main(String[] args) { MainMethod method = new MainMethod(); method.launchedFrame(); } class KeyListener extends KeyAdapter { public void keyPressed(KeyEvent e) { keyListener.addDirection(e); } public void keyReleased(KeyEvent e) { } } }三、错误截图
四、更改类名后（keyMonitorDemo.addDirection(e)不报错了）
五、错误原因 有可能是导入的类或继承的类中有了keyListener方法
