如何在同一個標​​籤中切換片段？

Question

我的小應用程序，具有以下基本結構（2個標籤在tabhost）：

主要（擴展FragmentActivity） HomeFragment（擴展片段） ConfigFragment（擴展片段）

有時（當用戶點擊菜單）我需要顯示其他片段（GraphicFragment），而不是HomeFragment。當我在GraphicFragment中並使用後退按鈕（或菜單項Home）時，該選項卡將再次顯示片段HomeFragment。

如何做到這一點？

main.xml中（佈局）：

<TabHost 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@android:id/tabhost" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"> 

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

     <TabWidget 
      android:id="@android:id/tabs" 
      android:orientation="horizontal" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      android:layout_weight="0" /> 

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

     <android.support.v4.view.ViewPager 
      android:id="@+id/viewpager" 
      android:layout_width="fill_parent" 
      android:layout_height="0dp" 
      android:layout_weight="1" /> 

    </LinearLayout> 

</TabHost> 

Main.java：

公共類主要延伸FragmentActivity {

private TabHost mTabHost; 
private ViewPager mViewPager; 
private HashMap<String, TabInfo> mapTabInfo = new HashMap<String, Main.TabInfo>(); 
private PagerAdapter mPagerAdapter; 
private Config config; 

private class TabInfo { 

    private String tag; 
    @SuppressWarnings("unused") 
    private Class<?> clss; 
    @SuppressWarnings("unused") 
    private Bundle args; 

    TabInfo(String tag, Class<?> clazz, Bundle args) { 
     this.tag = tag; 
     this.clss = clazz; 
     this.args = args; 
    } 

} 

private class TabFactory implements TabContentFactory { 

    private final Context mContext; 

    public TabFactory(Context context) { 
     mContext = context; 
    } 

    public View createTabContent(String tag) { 
     View v = new View(mContext); 
     v.setMinimumWidth(0); 
     v.setMinimumHeight(0); 
     return v; 
    } 

} 

public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main);  

    initializeTabHost(savedInstanceState); 
    if (savedInstanceState != null) { 
     mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab")); 
    } 

    intializeViewPager(); 

    config = Config.GetInstance(); 
    config.setContext(getApplicationContext());  
} 

private void initializeTabHost(Bundle args){ 
    mTabHost = (TabHost)findViewById(android.R.id.tabhost); 
    mTabHost.setup(); 

    TabInfo tabInfo = null; 

    Main.addTab(
     this, 
     mTabHost, 
     mTabHost.newTabSpec("Home").setIndicator("Home"), 
     (tabInfo = new TabInfo("Home", HomeFragment.class, args))); 
    mapTabInfo.put(tabInfo.tag, tabInfo); 

    Main.addTab(
     this, 
     mTabHost, 
     mTabHost.newTabSpec("Config").setIndicator("Config"), 
     (tabInfo = new TabInfo("Config", ConfigFragment.class, args))); 
    mapTabInfo.put(tabInfo.tag, tabInfo);   

    mTabHost.setOnTabChangedListener(tabChangeListener); 
} 

protected void onSaveInstanceState(Bundle outState) { 
    outState.putString("tab", mTabHost.getCurrentTabTag()); 
    outState.putString("tab", "Home"); 
    super.onSaveInstanceState(outState); 
} 

private void intializeViewPager() { 

    List<Fragment> fragments = new Vector<Fragment>(); 
    fragments.add(Fragment.instantiate(this, HomeFragment.class.getName())); 
    fragments.add(Fragment.instantiate(this, ConfigFragment.class.getName())); 
    fragments.add(Fragment.instantiate(this, GraphicFragment.class.getName())); 

    mPagerAdapter = new PagerAdapter(super.getSupportFragmentManager(), fragments); 

    mViewPager = (ViewPager)super.findViewById(R.id.viewpager); 
    mViewPager.setAdapter(mPagerAdapter); 
    mViewPager.setOffscreenPageLimit(4); 
    mViewPager.setOnPageChangeListener(pageChangeListener); 
} 

private static void addTab(Main activity, TabHost tabHost, TabHost.TabSpec tabSpec, TabInfo tabInfo) { 
    tabSpec.setContent(activity.new TabFactory(activity)); 
    tabHost.addTab(tabSpec); 
} 

private final TabHost.OnTabChangeListener tabChangeListener = new TabHost.OnTabChangeListener(){ 

    public void onTabChanged(String tabId) { 
     int pos = mTabHost.getCurrentTab(); 
     mViewPager.setCurrentItem(pos); 
    } 
}; 

private final ViewPager.OnPageChangeListener pageChangeListener = new ViewPager.OnPageChangeListener(){ 
    public void onPageScrollStateChanged(int state) {} 

    public void onPageScrolled(int arg0, float arg1, int arg2) {} 

    public void onPageSelected(int position) { 
     mTabHost.setCurrentTab(position); 
    } 
}; 

}

片段：

公共類HomeFragment擴展片段{

@SuppressWarnings("unused") 
private Config config = Config.GetInstance(); 

private View view; 

@SuppressWarnings("unused") 
private Context context;  

public void onCreate(Bundle savedInstanceState){ 
    super.onCreate(savedInstanceState); 
    setHasOptionsMenu(true); 
} 

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){ 

    if(container == null){ 
     return null; 
    } 

    view = (LinearLayout)inflater.inflate(R.layout.tab_graphic, container, false); 
    context = view.getContext(); 

    return view; 

} 

public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { 
    inflater.inflate(R.menu.tab_graphic, menu); 
} 

public boolean onOptionsItemSelected(MenuItem item) { 

    switch (item.getItemId()) { 
     case R.id.menu_home: 
      loadGraphicFragment(); 
    } 

    return false; 
} 

public void loadGraphicFragment(){ 

    Fragment fragment = new GraphicFragment(); 

    FragmentManager fm = getActivity().getSupportFragmentManager(); 
    FragmentTransaction transaction = fm.beginTransaction(); 
    transaction.replace(R.id.viewpager, fragment); 
    transaction.commit();  
} 

}

錯誤及時執行：

11-28 18:09:13.673: E/AndroidRuntime(468): Uncaught handler: thread main exiting due to uncaught exception 
11-28 18:09:13.695: E/AndroidRuntime(468): java.lang.NullPointerException 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.support.v4.app.Fragment.setUserVisibleHint(Fragment.java:801) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.support.v4.app.FragmentPagerAdapter.setPrimaryItem(FragmentPagerAdapter.java:130) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.support.v4.view.ViewPager.populate(ViewPager.java:1010) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:523) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:495) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.support.v4.view.ViewPager.setCurrentItem(ViewPager.java:476) 
11-28 18:09:13.695: E/AndroidRuntime(468): at br.com.censanet.connectionmonitor.Main$1.onTabChanged(Main.java:125) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.widget.TabHost.invokeOnTabChangeListener(TabHost.java:353) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.widget.TabHost.setCurrentTab(TabHost.java:338) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:129) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:379) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.View.performClick(View.java:2364) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.View.onTouchEvent(View.java:4179) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.View.dispatchTouchEvent(View.java:3709) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:852) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 
11-28 18:09:13.695: E/AndroidRuntime(468): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659) 
11-28 18:09:13.695: E/AndroidRuntime(468): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.app.Activity.dispatchTouchEvent(Activity.java:2061) 
11-28 18:09:13.695: E/AndroidRuntime(468): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.view.ViewRoot.handleMessage(ViewRoot.java:1691) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.os.Looper.loop(Looper.java:123) 
11-28 18:09:13.695: E/AndroidRuntime(468): at android.app.ActivityThread.main(ActivityThread.java:4363) 
11-28 18:09:13.695: E/AndroidRuntime(468): at java.lang.reflect.Method.invokeNative(Native Method) 
11-28 18:09:13.695: E/AndroidRuntime(468): at java.lang.reflect.Method.invoke(Method.java:521) 
11-28 18:09:13.695: E/AndroidRuntime(468): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 
11-28 18:09:13.695: E/AndroidRuntime(468): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 

請幫助 - 我！ （對不起英文！）

Answer 1

您可以從這裏下載示例代碼，對於選項卡類型的項目非常有用。

https://github.com/JakeWharton/Android-ViewPagerIndicator

更新 在這裏你可以找到更多的碎片。

change fragment