Question

我在运行时收到此错误。

java.lang.RuntimeException：无法恢复活动 java.lang.NullPointerException：尝试调用虚方法＆＃39; void android.app.ActionBar.setDisplayShowHomeEnabled（布尔值）＆＃39;在null 对象参考

堆栈跟踪：

01-22 06:32:55.509: E/AndroidRuntime(3728): FATAL EXCEPTION: main
01-22 06:32:55.509: E/AndroidRuntime(3728): Process: com.qrme.quranmadeeasy, PID: 3728
01-22 06:32:55.509: E/AndroidRuntime(3728): java.lang.RuntimeException: Unable to resume activity {com.qrme.quranmadeeasy/com.qrme.quranmadeeasy.InnerPageActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayShowHomeEnabled(boolean)' on a null object reference
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2951)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2982)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2365)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.ActivityThread.access$800(ActivityThread.java:144)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.os.Handler.dispatchMessage(Handler.java:102)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.os.Looper.loop(Looper.java:135)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.ActivityThread.main(ActivityThread.java:5221)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at java.lang.reflect.Method.invoke(Native Method)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at java.lang.reflect.Method.invoke(Method.java:372)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
01-22 06:32:55.509: E/AndroidRuntime(3728): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayShowHomeEnabled(boolean)' on a null object reference
01-22 06:32:55.509: E/AndroidRuntime(3728):     at com.qrme.quranmadeeasy.InnerPageActivity.ActionBar(InnerPageActivity.java:203)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at com.qrme.quranmadeeasy.InnerPageActivity.onResume(InnerPageActivity.java:71)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1241)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.Activity.performResume(Activity.java:6019)
01-22 06:32:55.509: E/AndroidRuntime(3728):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2940)
01-22 06:32:55.509: E/AndroidRuntime(3728):     ... 11 more

InnerPageActivity.java：

public class InnerPageActivity extends FragmentActivity {

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.copyactivity_single_page);

    }
@Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        initialize();
        ActionBar(); --->71 st line
 }


    public void ActionBar() {
        ActionBar mActionBar = getActionBar();
    mActionBar.setDisplayShowHomeEnabled(false); -->203rd line
    mActionBar.setDisplayShowTitleEnabled(false);
    mActionBar.setBackgroundDrawable(new ColorDrawable(Color
            .parseColor("#356AA0")));

    mActionBar.setCustomView(mCustomView);
    mActionBar.setDisplayShowCustomEnabled(true);
    }
}

styles.xml：

<resources>

    <style name="AppBaseTheme" parent="@style/Theme.AppCompat"></style>

    <!-- Application theme. -->
    <style name="AppTheme" parent="AppBaseTheme">
        <!-- All customizations that are NOT specific to a particular API-level can go here. -->
    </style>
</resources>

的manifest.xml：

    <uses-sdk
    android:minSdkVersion="16"
    android:targetSdkVersion="21" />

  <application
        android:name="com.qrme.quranmadeeasy.Application"
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:screenOrientation="portrait"            
               >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
     ........
    <application>

我不知道如何解决这个问题。任何人都可以帮助我。谢谢。

Answer 1

由于您使用的是支持主题（AppCompat）和支持活动（FragmentActivity），而不是

getActionBar()

呼叫

getSupportActionBar()

Answer 2

你应该改变

public class InnerPageActivity extends FragmentActivity

到

public class InnerPageActivity extends ActionBarActivity

并更改mActionBar = getSupportActionBar();

Answer 3

您可以从AppCompatActivity扩展并调用getSupportActionBar（）

FragmentActivity上ActionBar上的空指针异常

3 个答案: