我在 Activity 的 onCreate() 方法中创建了一个按钮,并尝试在 onRestoreInstanceState(Bundle) 方法中更改按钮的状态。我在这种方法中只有一行。
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState)
{
savedButton.setSelected(true);
super.onRestoreInstanceState(savedInstanceState);
}
但有时 java.lang.NullPointerException 异常发生在我更改按钮状态的这一行,有时它工作正常。
我哪里错了?
日志:
java.lang.NullPointerException
at com.test.MainActivity.onRestoreInstanceState(MainActivity.java:35)
at android.app.Activity.performRestoreInstanceState(Activity.java:934)
at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1145)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2088)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3576)
at android.app.ActivityThread.access$800(ActivityThread.java:143)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4950)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1004)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:771)
at dalvik.system.NativeStart.main(Native Method)