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我检查alert.class以查找错误,因为logcat文件在启动alert.class活动时显示错误,但找不到任何错误。
下面是代码:APP给出错误,并停止在Android上工作
public class alert extends Activity
{
Button button1;
Button button2;
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.alert);
button1 = (Button) findViewById(R.id.button1);
button2 = (Button) findViewById(R.id.button2);
button1.setOnClickListener(new OnClickListener()
{
public void onClick(View v1)
{
setContentView(R.layout.set);
Intent myIntent = new Intent(getApplicationContext(), set.class);
startActivity(myIntent);
}
});
button2.setOnClickListener(new OnClickListener()
{
public void onClick(View v1)
{
setContentView(R.layout.set);
Intent myIntent = new Intent(getApplicationContext(), set.class);
startActivity(myIntent);
}
});
}
}
这是logcat的:
03-23 08:28:28.239: E/AndroidRuntime(463): FATAL EXCEPTION: main
03-23 08:28:28.239: E/AndroidRuntime(463): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.indianic.demo.calendark/com.indianic.demo.calendark.alert}: java.lang.NullPointerException
03-23 08:28:28.239: E/AndroidRuntime(463): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.os.Handler.dispatchMessage(Handler.java:99)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.os.Looper.loop(Looper.java:123)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.app.ActivityThread.main(ActivityThread.java:3683)
03-23 08:28:28.239: E/AndroidRuntime(463): at java.lang.reflect.Method.invokeNative(Native Method)
03-23 08:28:28.239: E/AndroidRuntime(463): at java.lang.reflect.Method.invoke(Method.java:507)
03-23 08:28:28.239: E/AndroidRuntime(463): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-23 08:28:28.239: E/AndroidRuntime(463): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-23 08:28:28.239: E/AndroidRuntime(463): at dalvik.system.NativeStart.main(Native Method)
03-23 08:28:28.239: E/AndroidRuntime(463): Caused by: java.lang.NullPointerException
03-23 08:28:28.239: E/AndroidRuntime(463): at com.indianic.demo.calendark.alert.onCreate(alert.java:37)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-23 08:28:28.239: E/AndroidRuntime(463): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
03-23 08:28:28.239: E/AndroidRuntime(463): ... 11 more
任何线37,这就是你的错误。你得到一个NPE。在你的帖子里注释,第37行是 – ElefantPhace 2013-03-23 03:23:44
类名不应该是小写..他们应该是UpperCasedLikeThis。 – JoxTraex 2013-03-23 03:35:59
我在同一个应用程序中有很多课程,但是所有的活动都在正常工作 – Metalhead1247 2013-03-23 03:42:55