Android Studio中的FragmentTabHost

我正在尝试在我的应用程序中实现一个3标签系统

Index.java（3个选项卡应位于此处）

}

Index.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"   android:layout_width="match_parent"
android:layout_height="match_parent"     android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.example.vincent.tennispartner2.Index">

<android.support.v4.app.FragmentTabHost
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >

        <TabWidget
            android:id="@android:id/tabs"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom"/>

        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="fill_parent"
            android:layout_height="0dp"
            android:layout_weight="1" />
    </LinearLayout>

</android.support.v4.app.FragmentTabHost>
</RelativeLayout>

我在这方面已经坚持了好几个小时，从actionbar到碎片，从工具栏到其他东西，但我找不到任何适合我的东西。鉴于我刚刚开始用java/android编写代码，我真的需要一些帮助

完全错误：

08-25 15:41:22.085  13008-13008/com.example.vincent.tennispartner2     E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.vincent.tennispartner2, PID: 13008
    java.lang.RuntimeException: Unable to start activity     ComponentInfo{com.example.vincent.tennispartner2/com.example.vincent.tennispartn    er2.Index}: java.lang.NullPointerException: Attempt to invoke virtual method         'void android.support.v4.app.FragmentTabHost.setup(android.content.Context,         android.support.v4.app.FragmentManager, int)' on a null object reference
                at         android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2693)
                at       android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2760)
                at     android.app.ActivityThread.access$900(ActivityThread.java:177)
                at     android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
                at android.os.Handler.dispatchMessage(Handler.java:102)
                at android.os.Looper.loop(Looper.java:145)
                at android.app.ActivityThread.main(ActivityThread.java:5944)
                at java.lang.reflect.Method.invoke(Native Method)
                at java.lang.reflect.Method.invoke(Method.java:372)
                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.FragmentTabHost.setup(android.content.Context, android.support.v4.app.FragmentManager, int)' on a null object reference
                at com.example.vincent.tennispartner2.Index.onCreate(Index.java:25)
                at android.app.Activity.performCreate(Activity.java:6289)
                at     android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
                at     android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
                at     android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2760)
                at android.app.ActivityThread.access$900(ActivityThread.java:177)
                at     android.app.ActivityThread$H.handleMessage(ActivityThread.java:1448)
                at android.os.Handler.dispatchMessage(Handler.java:102)
                at android.os.Looper.loop(Looper.java:145)
                at android.app.ActivityThread.main(ActivityThread.java:5944)
                at java.lang.reflect.Method.invoke(Native Method)
                at java.lang.reflect.Method.invoke(Method.java:372)
                at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)

非常感谢任何提示

变化：

mTabHost = (FragmentTabHost) findViewById(android.R.id.tabhost);

致：

更改：

setContentView(R.layout.activity_index);

致：

---

更改会在tabhost上显示一个错误，表示无法解析符号。我在网上找到了您的示例。您是否这样做了：ANDROID STUDIO:ANDROID STUDIO不提供依赖项，因此您必须手动导入它们。文件>项目结构>应用程序（在“模块>依赖项”选项卡下）。单击底部的“+”添加库依赖项；在本例中为“support-v4”。Jup，今天早些时候这样做了，我从那里获得了当前代码

mTabHost = (FragmentTabHost) findViewById(android.R.id.tabhost);

mTabHost = (FragmentTabHost) findViewById(R.id.tabhost);

setContentView(R.layout.activity_index);

setContentView(R.layout.index);