java - Android - 如何使用 ActionBar 在 Fragment 之间导航

Question

ActionBar 和 Fragments 的新手，但总体上熟悉 Android。

我一直在学习一些教程。到目前为止，我有以下内容:

• 我想在其中导航的 3 个 Fragments(每个都有一个覆盖的 onCreateView() 并加载一个简单的 View )
• ActionBar 的自定义 TabListener(我相信问题就在那里，代码见文章底部)
• 托管 Activity，所有这些都在其中执行

Activity 代码:

public class Activity_Home extends Activity
{
ActionBar actionBar;

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);

    actionBar = getActionBar();  // Get reference to ActionBar

    // Add some navigation tabs...

    // 1. Enable ActionBar navigation tabs
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    actionBar.setDisplayShowTitleEnabled(false);

    // 2. Add the tabs
    Tab programTab = actionBar.newTab();
    Tab settingsTab = actionBar.newTab();
    Tab historyTab = actionBar.newTab();

    programTab.setText("Program")
              .setTabListener(new TabListener<Fragment_Program>(
                      this, R.id.fragmentParent, Fragment_Program.class));

    settingsTab.setText("Settings")
               .setTabListener(new TabListener<Fragment_Settings>(
                      this, R.id.fragmentParent, Fragment_Settings.class));

    historyTab.setText("History")
      .setTabListener(new TabListener<Fragment_History>(
              this, R.id.fragmentParent, Fragment_History.class));

    actionBar.addTab(programTab);
    actionBar.addTab(settingsTab);
    actionBar.addTab(historyTab);
}
}

我的 fragment :

public class Fragment_Program extends Fragment
{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState)
{
    return inflater.inflate(R.layout.fragment_program, null);
}
}

..

public class Fragment_History extends Fragment
{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState)
{
    return inflater.inflate(R.layout.fragment_history, null);
}
}

..

public class Fragment_Settings extends Fragment
{   
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState)
{
    return inflater.inflate(R.layout.fragment_settings, null);
}   
}

最后，我的 TabListener 几乎基于官方的 Google 示例。 fragmentContainer (int) 是 Activities 布局中 LinearLayout 的 XML 资源 ID，它是所有这些 Fragment 的直接父级。

public class TabListener <T extends Fragment> implements ActionBar.TabListener
{
private Fragment fragment;
private int fragmentContainer;
private final Activity activity;
private final Class<T> fragmentClass;

/** Constructor used each time a new tab is created.
 * @param activity  The host Activity, used to instantiate the fragment
 * @param tag  The identifier tag for the fragment
 * @param fragmentClass  The fragment's Class, used to instantiate the fragment
 */
public TabListener(Activity activity, int fragmentContainer, Class<T> fragmentClass)
{
    this.activity = activity;
    this.fragmentContainer = fragmentContainer;
    this.fragmentClass = fragmentClass;
}

@Override
public void onTabReselected(Tab arg0, FragmentTransaction arg1)
{
    // User selected the already selected tab. Usually do nothing.      
}

@Override
public void onTabSelected(Tab tab, FragmentTransaction ft)
{
    // Check if the fragment is already intialized
    if (fragment == null)
    {
        // If not, instatiate and add it to the Activity
        fragment = Fragment.instantiate(activity, fragmentClass.getName());

        ft.add(fragmentContainer, fragment);
    }       
    else
    {
        ft.attach(fragment);
    }
}

@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft)
{
    if (fragment != null)
    {
        // Detach the fragment, because another one is being attached
        ft.detach(fragment);
    }
}   

所以应用加载了，选项卡在那里，我可以选择它们，但它们似乎没有相互链接，我不确定如何继续。

任何建议都会很棒!

干杯

奖励问题:ActionBar 也在现有的 ActionBar 下方。目标是替换它，而不是在下面再做一个。再说一遍，任何建议都很好!

Answer 1

已修复!

我改变了我的方法，不再使用 Fragment Container ID(它确实对我来说更有意义......)和字符串标签，按照这个例子 Good complete Fragment and ActionBar example以及谷歌官方示例。