在操作栏空指针异常(Null pointer exception at action bar)

我在操作栏获得空指针异常。我使用getActionBar()继是在errors..I正在扩大活动

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.peoplecloud.guggu/com.peoplecloud.guggu.activity.LandingActivity_}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2211)
            at android.app.ActivityThread.access$600(ActivityThread.java:149)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:153)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.peoplecloud.guggu.activity.LandingActivity.onCreate(LandingActivity.java:96)
            at com.peoplecloud.guggu.activity.LandingActivity_.onCreate(LandingActivity_.java:29)
            at android.app.Activity.performCreate(Activity.java:5020)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2211)
            at android.app.ActivityThread.access$600(ActivityThread.java:149)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:153)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)

在下面的线 -

java:96 actionBar.setTitle(mTitle);

Answer 1:

如果您使用的活动，然后使用下面的代码

ActionBar actionBar = getActionBar();
actionBar.hide();

或者您正在使用ActionBarActivity然后getSupportActionBar（）

确保你没有使用NoTitlebar主题。

编辑

采用

    Toolbar mToolbar = (Toolbar)findViewById(R.id.toolbar);
    mToolbar.setTitle(mTitle);

并添加您的布局xml文件：

创建seprate文件

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#E3493B"
android:minHeight="?attr/actionBarSize"
app:theme="@style/ThemeOverlay.AppCompat.ActionBar" >

它包括在你的XML布局文件