Java android.app.Actionbar.setHomeButtonEnabled返回空值
我正在尝试在android中创建可切换的标签。在活动启动应用程序崩溃之前,表示setHomeButtonenabled返回nullpointerexception 我的onCreate方法:Java android.app.Actionbar.setHomeButtonEnabled返回空值,java,android,android-tabs,Java,Android,Android Tabs,我正在尝试在android中创建可切换的标签。在活动启动应用程序崩溃之前,表示setHomeButtonenabled返回nullpointerexception 我的onCreate方法: protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Initiliza
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
/**
* on swiping the viewpager make respective tab selected
* */
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
这是我的日志:
03-09 22:38:24.674: E/AndroidRuntime(1297): FATAL EXCEPTION: main
03-09 22:38:24.674: E/AndroidRuntime(1297): Process: com.appquest.prodactivity, PID: 1297
03-09 22:38:24.674: E/AndroidRuntime(1297): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.appquest.prodactivity/com.appquest.prodactivity.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setHomeButtonEnabled(boolean)' on a null object reference
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.ActivityThread.access$800(ActivityThread.java:144)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.os.Handler.dispatchMessage(Handler.java:102)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.os.Looper.loop(Looper.java:135)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.ActivityThread.main(ActivityThread.java:5221)
03-09 22:38:24.674: E/AndroidRuntime(1297): at java.lang.reflect.Method.invoke(Native Method)
03-09 22:38:24.674: E/AndroidRuntime(1297): at java.lang.reflect.Method.invoke(Method.java:372)
03-09 22:38:24.674: E/AndroidRuntime(1297): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
03-09 22:38:24.674: E/AndroidRuntime(1297): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
03-09 22:38:24.674: E/AndroidRuntime(1297): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setHomeButtonEnabled(boolean)' on a null object reference
03-09 22:38:24.674: E/AndroidRuntime(1297): at com.appquest.prodactivity.MainActivity.onCreate(MainActivity.java:31)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.Activity.performCreate(Activity.java:5933)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
03-09 22:38:24.674: E/AndroidRuntime(1297): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
我使用的是minimumsdk=14和target=21,如果您的活动扩展了ActionBarActivity,那么请更改
actionBar = getActionBar();
到
**将AndroidManifest文件主题更改为@android:style/theme.Holo.Light更改活动的主题 这样地 android:theme=“@android:style/theme.Holo.Light.DialogWhenLarge”
我的活动扩展到FragmentActivity并实现ActionBar。TabListener@Harsh不要使用
ActionBar.TabListener
,这是不推荐使用的。是的,我知道。还有其他简单的创建选项卡的方法吗?@Pooja如果他使用的是minSdk of 14,他很可能没有使用AppCompat。@是的,但不是一个好主意。请在此处查看我的答案:。请使用AppCompatActivity而不是FragmentActivity
actionBar = getSupportedActionBar();