我在运行时收到空指针异常。我在下面的代码中指出了错误行。
我收到此错误:
java.lang.RuntimeException:无法启动活动 java.lang.NullPointerException:尝试调用虚方法'void 空对象上的android.app.ActionBar.setHomeButtonEnabled(boolean)' 参考
堆栈跟踪:
01-21 11:12:12.060: E/AndroidRuntime(2102): at android.app.ActivityThread.access$800(ActivityThread.java:144)
01-21 11:22:37.975: E/AndroidRuntime(2176): FATAL EXCEPTION: main
01-21 11:22:37.975: E/AndroidRuntime(2176): Process: com.qrme.quranmadeeasy, PID: 2176
01-21 11:22:37.975: E/AndroidRuntime(2176): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.qrme.quranmadeeasy/com.qrme.quranmadeeasy.ChapterActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.ActivityThread.access$800(ActivityThread.java:144)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.os.Handler.dispatchMessage(Handler.java:102)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.os.Looper.loop(Looper.java:135)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.ActivityThread.main(ActivityThread.java:5221)
01-21 11:22:37.975: E/AndroidRuntime(2176): at java.lang.reflect.Method.invoke(Native Method)
01-21 11:22:37.975: E/AndroidRuntime(2176): at java.lang.reflect.Method.invoke(Method.java:372)
01-21 11:22:37.975: E/AndroidRuntime(2176): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
01-21 11:22:37.975: E/AndroidRuntime(2176): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
01-21 11:22:37.975: E/AndroidRuntime(2176): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
01-21 11:22:37.975: E/AndroidRuntime(2176): at com.qrme.quranmadeeasy.ChapterActivity.onCreate(ChapterActivity.java:64)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.Activity.performCreate(Activity.java:5933)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
01-21 11:22:37.975: E/AndroidRuntime(2176): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
01-21 11:22:37.975: E/AndroidRuntime(2176): ... 10 more
ChapterActivity.java:
public class ChapterActivity extends Activity implements OnItemClickListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
setContentView(R.layout.activity_chapter);
getActionBar().setDisplayHomeAsUpEnabled(true); --->64th line error
getActionBar().setHomeButtonEnabled(true);
initialize();
listChapter.setOnItemClickListener(this);
}
private void initialize() {
.....
....
ActionBar();
}
public void ActionBar() {
ActionBar mActionBar = getActionBar();
mActionBar.setBackgroundDrawable(new ColorDrawable(Color
.parseColor(white)));
mActionBar.setDisplayShowHomeEnabled(false);
mActionBar.setDisplayShowTitleEnabled(false);
LayoutInflater mInflater = LayoutInflater.from(this);
View mCustomView = mInflater.inflate(R.layout.custom_actionbar, null);
Typeface type = Typeface.createFromAsset(getAssets(),
"Roboto-Medium.ttf");
TextView mTitleTextView = (TextView) mCustomView
.findViewById(R.id.textviewHeading);
mTitleTextView.setTypeface(type);
ImageButton imgbuttonSettings = (ImageButton) mCustomView
.findViewById(R.id.imagebuttonSettings);
ImageButton imgbuttonPre = (ImageButton) mCustomView
.findViewById(R.id.imagebuttonPre);
imgbuttonPre.setVisibility(View.GONE);
imgbuttonSettings.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
startActivity(new Intent(ChapterActivity.this,
SettingsActivity.class));
}
});
mActionBar.setCustomView(mCustomView);
mActionBar.setDisplayShowCustomEnabled(true);
}
}
清单:
<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"
android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
........
<applicaiton>
任何人都可以帮我解决这个问题。谢谢。
答案 0 :(得分:0)
从清单文件中删除此行
android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen"
这表示全屏表示没有标题栏或操作栏,因此您正在获得NPE。
修改强>
同时将此行移至Actionbar()
函数
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
public void ActionBar() {
ActionBar mActionBar = getActionBar();
mActionBar.setDisplayHomeAsUpEnabled(true);
mActionBar.setHomeButtonEnabled(true);
}