這是控制臺(tái)的所顯示的結(jié)果： Exception?in?thread?"main"?java.lang.NullPointerException at?com.zyn_1.WriteNote.myEvent(WriteNote.java:36) at?com.zyn_1.WriteNote.init(WriteNote.java:30) at?com.zyn_1.WriteNote.<init>(WriteNote.java:14) at?com.zyn_1.WriteNote.main(WriteNote.java:46) 這是源代碼：package?com.zyn_1; import?java.awt.*; import?java.awt.event.*; public?class?WriteNote?{ private?Frame?f; private?MenuBar?mb; private?Menu?m; private?MenuItem?mi; WriteNote(){ init(); } public?void?init(){ Frame?f?=?new?Frame("記事本");//創(chuàng)建frame窗體 //對(duì)窗體進(jìn)行基本設(shè)置 f.setLayout(new?FlowLayout());//設(shè)置布局 f.setLocation(300,?100);//位置 f.setSize(500,600); //大小 mb?=?new?MenuBar(); m?=?new?Menu("文件"); mi?=?new?MenuItem("退出"); mb.add(m); m.add(mi); myEvent(); f.setMenuBar(mb); f.setVisible(true);//通過(guò)setvisiable（true）顯示窗體 } public?void?myEvent(){ f.addWindowListener(new?WindowAdapter()?{ public??void?windowClosing(WindowEvent?e){ System.exit(0); } }); } public?static?void?main(String[]?args)?{ //?TODO?Auto-generated?method?stub new?WriteNote(); } }