FragmentTabHost в Android Studio

Question

Я пытаюсь реализовать 3-полосную систему в своем приложении.

Index.java (Там, где 3 вкладки должны быть расположены)

public class Index extends FragmentActivity{ 
private FragmentTabHost mTabHost; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_index); 
    mTabHost = (FragmentTabHost) findViewById(android.R.id.tabhost); 
    mTabHost.setup(this, getSupportFragmentManager(),   android.R.id.tabcontent); 
    mTabHost.addTab(
      mTabHost.newTabSpec("tab1").setIndicator("Tab 1", null), 
      FragmentTab.class, null); 
    mTabHost.addTab(
      mTabHost.newTabSpec("tab2").setIndicator("Tab 2", null), 
      FragmentTab.class, null); 
    mTabHost.addTab(
      mTabHost.newTabSpec("tab3").setIndicator("Tab 3", null), 
      FragmentTab.class, null); 
} 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    MenuInflater inflater = getMenuInflater(); 
    inflater.inflate(R.menu.menu_index,menu); 

    return super.onCreateOptionsMenu(menu); 
} 
@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    // Handle action bar item clicks here. The action bar will 
    // automatically handle clicks on the Home/Up button, so long 
    // as you specify a parent activity in AndroidManifest.xml. 
    int id = item.getItemId(); 

    //noinspection SimplifiableIfStatement 
    if (id == R.id.action_settings) { 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 

}

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> 

FragmentTab.java

/** 
* Created by Vincent on 2015-08-25. 
*/ 
public class FragmentTab extends Fragment { 

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

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    View v = inflater.inflate(R.layout.fragment_layout, container, false); 
    TextView tv = (TextView) v.findViewById(R.id.text); 
    tv.setText(this.getTag() + " Content"); 
    return v; 
} 
} 

Ive было застрял на этой части для хоу rs, переходя от панели действий к фрагментам на панель инструментов к другим вещам, но я не могу найти ничего, что сработает для меня. Видя, как я только начал кодировать в java/android, я мог бы действительно помочь с этим.

Полное Ошибка:

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) 

Любые советы высоко оценили!

Answer 1

Изменение:

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

To:

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

Answer 2

Изменение:

setContentView(R.layout.activity_index); 

To:

setContentView(R.layout.index);