j2me项目调试易出错1,startApp threw an Exception,java.lang.NullPointerException,
2007-11-08 23:56
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例如:netbeans开发工具中build.xml(debug) 中出现这样的错误:
startApp threw an Exception
java.lang.NullPointerException
java.lang.NullPointerException
at cn.edu.uestc.pandawireless.ui.WelcomeUI.scale(+1)
at cn.edu.uestc.pandawireless.ui.WelcomeUI.<init>(WelcomeUI.java:33)
at cn.edu.uestc.pandawireless.ui.UIControler.initUpdate(UIControler.java:78)
at cn.edu.uestc.pandawireless.LibMidlet.startApp(LibMidlet.java:71)
at javax.microedition.midlet.MIDletProxy.startApp(MIDletProxy.java:44)
at com.sun.midp.midlet.Scheduler.schedule(Scheduler.java:372)
at com.sun.midp.main.Main.runLocalClass(Main.java:461)
at com.sun.midp.main.Main.main(Main.java:126)
从提示中可以看出是在welcomeUI类的scale方法位置出错。原程序内容为:
private Image getImage(String path){
Image image = null;
//Image img = null;
try{
image = Image.createImage(path);
return image;
}catch (IOException e){
image = null;
return image;
}
}
这是因为image没有加载到图片(比如名称不对),为null造成java.lang.NullPointerException的错误。
解决方法就是加载正确的图片,或者在使用Image对象的时候判断是否非null,增加相应语句。
遇到具体问题可用根据提示分析问题解决问题!!!
startApp threw an Exception
java.lang.NullPointerException
java.lang.NullPointerException
at cn.edu.uestc.pandawireless.ui.WelcomeUI.scale(+1)
at cn.edu.uestc.pandawireless.ui.WelcomeUI.<init>(WelcomeUI.java:33)
at cn.edu.uestc.pandawireless.ui.UIControler.initUpdate(UIControler.java:78)
at cn.edu.uestc.pandawireless.LibMidlet.startApp(LibMidlet.java:71)
at javax.microedition.midlet.MIDletProxy.startApp(MIDletProxy.java:44)
at com.sun.midp.midlet.Scheduler.schedule(Scheduler.java:372)
at com.sun.midp.main.Main.runLocalClass(Main.java:461)
at com.sun.midp.main.Main.main(Main.java:126)
从提示中可以看出是在welcomeUI类的scale方法位置出错。原程序内容为:
private Image getImage(String path){
Image image = null;
//Image img = null;
try{
image = Image.createImage(path);
return image;
}catch (IOException e){
image = null;
return image;
}
}
这是因为image没有加载到图片(比如名称不对),为null造成java.lang.NullPointerException的错误。
解决方法就是加载正确的图片,或者在使用Image对象的时候判断是否非null,增加相应语句。
遇到具体问题可用根据提示分析问题解决问题!!!
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