我有一个显示 ListView 的活动。我想在 25 秒后调用 Activity 的 onBackPressed() 。目前它正在导致NPE。谁能告诉我为什么?谢谢。它也不显示listView,它立即返回调用屏幕,然后在指定时间后,NPE 发生。
@Override
protected void onNewIntent(Intent intent) {
setIntent(intent);
super.onNewIntent(intent);
}
Handler handler = new Handler();
Runnable runnable = new Runnable() {
public void run() {
returnToMenu();
}
private void returnToMenu() {
handler.postDelayed(runnable, 25000);
onBackPressed();
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.getrotalayout);
setCurrentDateOnView();
nfcscannerapplication = (NfcScannerApplication) getApplication();
//set titlebar to carer's name
Cursor cursorCarerName = nfcscannerapplication.loginValidate.queryAllFromCarer();
cursorCarerName.moveToLast();
String carerTitleName = cursorCarerName.getString(cursorCarerName
.getColumnIndex(LoginValidate.C_CARER_FIRSTNAME)) + " " + cursorCarerName.getString(cursorCarerName
.getColumnIndex(LoginValidate.C_CARER_LASTNAME)) ;
setTitle(carerTitleName + " is currently logged in");
listView = (ListView) findViewById(R.id.rotalist);
textViewDate = (TextView)findViewById(R.id.textviewdate);
Log.e(TAG, "textview = "+textViewDate);
listView.setAdapter(arrayAdapter);
listView.setOnItemClickListener(this);
runnable.run();
}// end of onCreate
.
10-25 10:00:25.780: E/AndroidRuntime(20896): FATAL EXCEPTION: main
10-25 10:00:25.780: E/AndroidRuntime(20896): java.lang.NullPointerException
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1359)
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:439)
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:454)
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.app.Activity.onBackPressed(Activity.java:2185)
10-25 10:00:25.780: E/AndroidRuntime(20896): at com.carefreegroup.GetRota$1.returnToMenu(GetRota.java:77)
10-25 10:00:25.780: E/AndroidRuntime(20896): at com.carefreegroup.GetRota$1.run(GetRota.java:70)
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.os.Handler.handleCallback(Handler.java:608)
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.os.Handler.dispatchMessage(Handler.java:92)
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.os.Looper.loop(Looper.java:156)
10-25 10:00:25.780: E/AndroidRuntime(20896): at android.app.ActivityThread.main(ActivityThread.java:5045)
10-25 10:00:25.780: E/AndroidRuntime(20896): at java.lang.reflect.Method.invokeNative(Native Method)
10-25 10:00:25.780: E/AndroidRuntime(20896): at java.lang.reflect.Method.invoke(Method.java:511)
10-25 10:00:25.780: E/AndroidRuntime(20896): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
10-25 10:00:25.780: E/AndroidRuntime(20896): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
10-25 10:00:25.780: E/AndroidRuntime(20896): at dalvik.system.NativeStart.main(Native Method)