當我啓動我的活動時,我不斷收到nullpointerexception。我試圖讓一個tic tac toe遊戲的分數顯示在TextView的Action Bar中,但每當我嘗試設置onPrepareOptionsMenu()方法中的文本時,應用程序都會崩潰。實際上,我使用一個ActionView將這個小部件放在Action Bar中。爲什麼動態修改ActionBar中的TextView時出現nullpointerexception?
下面是代碼在我RES /菜單/ score_show.xml:
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:yourapp="http://schemas.android.com/apk/res-auto" >
<item
android:id="@+id/action_settings"
android:orderInCategory="100"
android:showAsAction="never"
android:title="@string/action_settings"/>
<item
android:id="@+id/scoreTextItem"
yourapp:showAsAction="always|withText"
android:actionViewClass="android.widget.TextView"
yourapp:actionViewClass="@layout/score_text"/>
</menu>
而且我RES /佈局/ score_text.xml:
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/scoreText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true" >
</TextView>
最後,一片段的TicTacToeActivity.java:
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.score_show, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
scoreItem = menu.findItem(R.id.scoreTextItem);
TextView scoreText = (TextView)MenuItemCompat.getActionView(scoreItem);
scoreText.setText("P1: " + humanScore + " P2: " + computerScore);
supportInvalidateOptionsMenu();
return super.onPrepareOptionsMenu(menu);
}
這裏是我的logcat
03-13 00:40:09.244: D/AndroidRuntime(1127): Shutting down VM
03-13 00:40:09.248: E/AndroidRuntime(1127): FATAL EXCEPTION: main
03-13 00:40:09.248: E/AndroidRuntime(1127): Process: com.packagename.tictactoe, PID: 1127
03-13 00:40:09.248: E/AndroidRuntime(1127): java.lang.NullPointerException
03-13 00:40:09.248: E/AndroidRuntime(1127): at com.packagename.tictactoe.TicTacToeActivity.onPrepareOptionsMenu(TicTacToeActivity.java:618)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.app.Activity.onPreparePanel(Activity.java:2556)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v4.app.FragmentActivity.onPrepareOptionsPanel(FragmentActivity.java:491)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v7.app.ActionBarActivity.superOnPrepareOptionsPanel(ActionBarActivity.java:240)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v7.app.ActionBarActivityDelegate.onPrepareOptionsPanel(ActionBarActivityDelegate.java:160)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v7.app.ActionBarActivity.onPrepareOptionsPanel(ActionBarActivity.java:212)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v4.app.FragmentActivity.onPreparePanel(FragmentActivity.java:480)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v7.app.ActionBarActivity.superOnPreparePanel(ActionBarActivity.java:236)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v7.app.ActionBarActivityDelegateICS.onPreparePanel(ActionBarActivityDelegateICS.java:155)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v7.app.ActionBarActivity.onPreparePanel(ActionBarActivity.java:204)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.support.v7.app.ActionBarActivityDelegateICS$WindowCallbackWrapper.onPreparePanel(ActionBarActivityDelegateICS.java:290)
03-13 00:40:09.248: E/AndroidRuntime(1127): at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:464)
03-13 00:40:09.248: E/AndroidRuntime(1127): at com.android.internal.policy.impl.PhoneWindow.doInvalidatePanelMenu(PhoneWindow.java:800)
03-13 00:40:09.248: E/AndroidRuntime(1127): at com.android.internal.policy.impl.PhoneWindow$1.run(PhoneWindow.java:221)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.view.Choreographer.doFrame(Choreographer.java:543)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.os.Handler.handleCallback(Handler.java:733)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.os.Handler.dispatchMessage(Handler.java:95)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.os.Looper.loop(Looper.java:136)
03-13 00:40:09.248: E/AndroidRuntime(1127): at android.app.ActivityThread.main(ActivityThread.java:5017)
03-13 00:40:09.248: E/AndroidRuntime(1127): at java.lang.reflect.Method.invokeNative(Native Method)
03-13 00:40:09.248: E/AndroidRuntime(1127): at java.lang.reflect.Method.invoke(Method.java:515)
03-13 00:40:09.248: E/AndroidRuntime(1127): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
03-13 00:40:09.248: E/AndroidRuntime(1127): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
03-13 00:40:09.248: E/AndroidRuntime(1127): at dalvik.system.NativeStart.main(Native Method)
謝謝! whaen從一個活性起着移動到另一個只檢查
您還沒有初始化的東西把整個的.java代碼
是什麼humanScore,computerScore變量
請把你的日誌,當你有錯誤。 – Amadas
對不起,我只是把它。 – aindurti