Java Android-如何更改导航抽屉中的片段

我对Android编程相当陌生，但到目前为止一直做得很好。我已经读了很多关于这个问题的答案，但似乎无法让我的答案起作用。基本上我有一个带导航抽屉的主要活动。我有两个片段使用相应的片段布局XML正确初始化。目前，我可以在应用程序启动时看到我的第一个片段，当我点击抽屉中的每个项目时，标题会改变；但是，片段保持不变。有什么建议吗？下面是我认为相关的代码（未显示的是NavigationDrawerFragment.java的代码以及Eclipse自动生成的必要代码）。提前谢谢

public class MainActivity extends Activity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {

/**
 * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
 */
private NavigationDrawerFragment mNavigationDrawerFragment;

/**
 * Used to store the last screen title. For use in {@link #restoreActionBar()}.
 */
private CharSequence mTitle;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mNavigationDrawerFragment = (NavigationDrawerFragment)
            getFragmentManager().findFragmentById(R.id.navigation_drawer);
    mTitle = getTitle();

    // Set up the drawer.
    mNavigationDrawerFragment.setUp(
            R.id.navigation_drawer,
            (DrawerLayout) findViewById(R.id.drawer_layout));


}

@Override
public void onNavigationDrawerItemSelected(int position) {
    // update the main content by replacing fragments

    FragmentManager fragmentManager = getFragmentManager();
    fragmentManager.beginTransaction()
            .replace(R.id.content_frame, PlaceholderFragment.newInstance(position + 1))
            .commit();

}

public void onSectionAttached(int number) {
    switch (number) {
        case 1:
            mTitle = getString(R.string.title_home);
            break;
        case 2:
            mTitle = getString(R.string.title_infodirect);
            break;
        case 3:
            mTitle = getString(R.string.title_trailmap);
            break;
        case 4:
            mTitle = getString(R.string.title_poi);
            break;
        case 5:
            mTitle = getString(R.string.title_photomap);
            break;
        case 6:
            mTitle = getString(R.string.title_report);
            break;
        case 7:
            mTitle = getString(R.string.title_rulesreg);

    }
}

public void restoreActionBar() {
    ActionBar actionBar = getActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
    actionBar.setDisplayShowTitleEnabled(true);
    actionBar.setTitle(mTitle);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    if (!mNavigationDrawerFragment.isDrawerOpen()) {
        // Only show items in the action bar relevant to this screen
        // if the drawer is not showing. Otherwise, let the drawer
        // decide what to show in the action bar.
        getMenuInflater().inflate(R.menu.overview, menu);
        restoreActionBar();
        return true;
    }
    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();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    private static final String ARG_SECTION_NUMBER = "section_number";

    /**
     * Returns a new instance of this fragment for the given section
     * number.
     */
    public static PlaceholderFragment newInstance(int sectionNumber) {
        PlaceholderFragment fragment = new PlaceholderFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_home, container, false);
        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        ((MainActivity) activity).onSectionAttached(
                getArguments().getInt(ARG_SECTION_NUMBER));
    }
}

public static class InfoDirectFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    private static final String ARG_SECTION_NUMBER = "section_number";

    /**
     * Returns a new instance of this fragment for the given section
     * number.
     */
    public static InfoDirectFragment newInstance(int sectionNumber) {
        InfoDirectFragment fragment = new InfoDirectFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public InfoDirectFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_infodirect, container, false);
        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        ((MainActivity) activity).onSectionAttached(
                getArguments().getInt(ARG_SECTION_NUMBER));
    }
}
}

请按照此操作了解更多详细信息并使用

private class DrawerItemClickListener implements
            ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
            selectItem(position);
        }
    }

---

我使用的导航抽屉也是基于Eclipse生成的（你的看起来也像是用它制作的），我对它进行了一些删减，这样它就不那么愚蠢了。我在某些时候也做了一些黑魔法，因为我遇到了一些愚蠢的错误，这些错误我已经修复了很多次（例如，无法在背压时更新操作栏标题，或者如果旋转屏幕，则索引0处的元素将由活动重新创建）：

导航性：

public class NavigationDrawerActivity extends ActionBarActivity implements
    NavigationDrawerFragment.NavigationDrawerCallbacks
{

/**
 * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
 */
private NavigationDrawerFragment mNavigationDrawerFragment;

/**
 * Used to store the last screen title. For use in {@link #restoreActionBar()}.
 */
private CharSequence mTitle;

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mNavigationDrawerFragment = (NavigationDrawerFragment) getSupportFragmentManager()
            .findFragmentById(R.id.navigation_drawer);
    mTitle = getString(R.string.drawer_0);

    // Set up the drawer.
    mNavigationDrawerFragment.setUp(R.id.navigation_drawer,
            (DrawerLayout) findViewById(R.id.drawer_layout));
    getSupportFragmentManager().addOnBackStackChangedListener(new OnBackStackChangedListener()
    {
        public void onBackStackChanged()
        {
            int backCount = getSupportFragmentManager().getBackStackEntryCount();
            if (backCount == 0)
            {
                finish();
            }
            else
            {
                Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.container);
                mTitle = getString(((GetActionBarTitle) fragment).getActionBarTitleId());
                restoreActionBar();
            }
        }
    });
    if (savedInstanceState != null)
    {
        this.onBackPressed();
    }
}

public void restoreActionBar()
{
    ActionBar actionBar = getSupportActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
    actionBar.setDisplayShowTitleEnabled(true);
    actionBar.setTitle(mTitle);
}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
    if (!mNavigationDrawerFragment.isDrawerOpen())
    {
        // Only show items in the action bar relevant to this screen
        // if the drawer is not showing. Otherwise, let the drawer
        // decide what to show in the action bar.
        getMenuInflater().inflate(R.menu.main, menu);
        restoreActionBar();
        return true;
    }
    return super.onCreateOptionsMenu(menu);
}

@Override
public void onNavigationDrawerItemSelected(int position)
{
    // update the main content by replacing fragments
    FragmentManager fragmentManager = getSupportFragmentManager();
    boolean addToBackStack = true;
    Fragment fragment = null;
    switch (position)
    {
        case 0:
            fragment = new Fragment0();
            break;
        case 1:
            fragment = new Fragment1();
            break;
        case 2:
            fragment = new Fragment2();
            break;
        case 3:
            fragment = new Fragment3();
            break;
        case 4:
            fragment = new Fragment4();
            break;
        case 5:
            logout();
        default:
            Log.w(this.getClass().getSimpleName(),
                    "Reached Default in onNavigationDrawerItemSelected!");
            break;
    }
    if (fragment != null)
    {
        FragmentTransaction ft = fragmentManager.beginTransaction();
        ft.replace(R.id.container, fragment);
        if (addToBackStack == true)
        {
            ft.addToBackStack(null);
        }
        ft.commit();
        mTitle = getString(((GetActionBarTitle) fragment).getActionBarTitleId());
        restoreActionBar();
    }
}

public void logout()
{
    this.finish();
}


}

阴险的“GetActionBarTitle”：

生成的NavigationDrawerFragment（我认为我根本没有更改它）：

我希望这能如你所愿。我必须对BackbackListener和其他东西施魔法才能正常工作

@Override
public void onNavigationDrawerItemSelected(int position) {
    // update the main content by replacing fragments

    FragmentManager fragmentManager = getSupportFragmentManager();

    if (position == 0) {  
        fragmentManager.beginTransaction() 
             .replace(R.id.container, FirstFragment.newInstance())  
             .commit();  
    } else if (position == 1) {  
       fragmentManager.beginTransaction()  
         .replace(R.id.container, SecondFragment.newInstance())  
         .commit();  
    } else if (position == 2) {  
       fragmentManager.beginTransaction()  
         .replace(R.id.container, ThridFragment.newInstance())  
         .commit();  
    }  

}

并创建片段

public class FirstFragment extends Fragment {  

   public static FirstFragment newInstance() {
     FirstFragment fragment = new FirstFragment();  
     return fragment;  
   }  

   public FirstFragment() {  
   }  

   @Override  
   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {  
       View rootView = inflater.inflate(R.layout.fragment_first, container, false);  
       return rootView;  
   }  

   @Override  
   public void onAttach(Activity activity) {  
       super.onAttach(activity);  
       ((MainActivity) activity).onSectionAttached(1);  
   }  
}  

---

我知道这很古老，但我想和大家分享我写的一些关于应用程序抽屉和片段导航的文章。它们是最新的样品（至少2017年）。请随时查看：

---

几天前我看到了这个链接，但我犹豫是否要继续，因为它几乎需要修改我所有的代码。既然是你建议的，我决定还是试试看。结果证明它工作得很好，很值得修改我的代码。非常感谢你！干得好。但如果我想每次打开一个片段。若再次从导航抽屉中选择相同的标题，那个么它应该使用以前打开过的片段。@BSKANIA是的，尽管我还并没有弄清楚。我猜我应该跟踪它们，并从功能上重新实现FragmentPagerAdapter或FragmentStatePagerAdapter，但我还没有弄明白，而且我从来都不需要完成它。@BSKANIA其实不应该那么难，因为考虑到我将数据存储在后台，可以使用片段backstack条目ID

FragmentManager#getBackStackEntryAt（int）

和

FragmentManager#getBackStackEntry（）

访问它。需要注意的是，旋转屏幕后，它会调用display（0），这就是我调用onBackPressed（）的原因，但这需要更改为只显示当前片段，而不是0。。如果方向改变是允许的，那就需要黑魔法了。但是，除此之外，我不需要实现这一点，但这是开始。目前，这就是我用来处理backbackback的方法。@BSKANIA虽然你可以做到这一点，但我不确定Android不管理它们是什么意思。这就是

addToBackStack（null）

调用的目的。我尝试了您的解决方案，但我的第一个片段没有加载布局！！

public class NavigationDrawerFragment extends Fragment
{

/**
 * Remember the position of the selected item.
 */
private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position";

/**
 * Per the design guidelines, you should show the drawer on launch until the user manually expands
 * it. This shared
 * preference tracks this.
 */
private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";

/**
 * A pointer to the current callbacks instance (the Activity).
 */
private NavigationDrawerCallbacks mCallbacks;

/**
 * Helper component that ties the action bar to the navigation drawer.
 */
private ActionBarDrawerToggle mDrawerToggle;

private DrawerLayout mDrawerLayout;
private ListView mDrawerListView;
private View mFragmentContainerView;

private int mCurrentSelectedPosition = 0;
private boolean mFromSavedInstanceState;
private boolean mUserLearnedDrawer;

public NavigationDrawerFragment()
{
}

/**
 * Callbacks interface that all activities using this fragment must implement.
 */
public static interface NavigationDrawerCallbacks
{
    /**
     * Called when an item in the navigation drawer is selected.
     */
    void onNavigationDrawerItemSelected(int position);
}

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

    // Read in the flag indicating whether or not the user has demonstrated awareness of the
    // drawer. See PREF_USER_LEARNED_DRAWER for details.
    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
    mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false);

    if (savedInstanceState != null)
    {
        mCurrentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION);
        mFromSavedInstanceState = true;
    }

    // Select either the default item (0) or the last selected item.
    selectItem(mCurrentSelectedPosition);
}

@Override
public void onActivityCreated(Bundle savedInstanceState)
{
    super.onActivityCreated(savedInstanceState);
    // Indicate that this fragment would like to influence the set of actions in the action bar.
    setHasOptionsMenu(true);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
    mDrawerListView = (ListView) inflater.inflate(R.layout.fragment_navigation_drawer, container,
            false);
    mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener()
    {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id)
        {
            selectItem(position);
        }
    });
    String[] drawerTitles = new String[] { getString(R.string.drawer_0),
            getString(R.string.drawer_1),
            getString(R.string.drawer_2), getString(R.string.drawer_3),
            getString(R.string.drawer_4), getString(R.string.drawer_5) };
    mDrawerListView.setAdapter(new ArrayAdapter<String>(getActionBar().getThemedContext(),
            android.R.layout.simple_list_item_1, android.R.id.text1, drawerTitles));
    mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
    return mDrawerListView;
}

public boolean isDrawerOpen()
{
    return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView);
}

/**
 * Users of this fragment must call this method to set up the navigation drawer interactions.
 * 
 * @param fragmentId
 *            The android:id of this fragment in its activity's layout.
 * @param drawerLayout
 *            The DrawerLayout containing this fragment's UI.
 */
public void setUp(int fragmentId, DrawerLayout drawerLayout)
{
    mFragmentContainerView = getActivity().findViewById(fragmentId);
    mDrawerLayout = drawerLayout;

    // set a custom shadow that overlays the main content when the drawer opens
    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
    // set up the drawer's list view with items and click listener

    ActionBar actionBar = getActionBar();
    actionBar.setDisplayHomeAsUpEnabled(true);
    actionBar.setHomeButtonEnabled(true);

    // ActionBarDrawerToggle ties together the the proper interactions
    // between the navigation drawer and the action bar app icon.
    mDrawerToggle = new ActionBarDrawerToggle(getActivity(), /* host Activity */
    mDrawerLayout, /* DrawerLayout object */
    R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */
    R.string.navigation_drawer_open, /* "open drawer" description for accessibility */
    R.string.navigation_drawer_close /* "close drawer" description for accessibility */
    )
    {
        @Override
        public void onDrawerClosed(View drawerView)
        {
            super.onDrawerClosed(drawerView);
            if (!isAdded())
            {
                return;
            }

            getActivity().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu()
        }

        @Override
        public void onDrawerOpened(View drawerView)
        {
            super.onDrawerOpened(drawerView);
            if (!isAdded())
            {
                return;
            }

            if (!mUserLearnedDrawer)
            {
                // The user manually opened the drawer; store this flag to prevent auto-showing
                // the navigation drawer automatically in the future.
                mUserLearnedDrawer = true;
                SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
                sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
            }

            getActivity().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu()
        }
    };

    // If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
    // per the navigation drawer design guidelines.
    if (!mUserLearnedDrawer && !mFromSavedInstanceState)
    {
        mDrawerLayout.openDrawer(mFragmentContainerView);
    }

    // Defer code dependent on restoration of previous instance state.
    mDrawerLayout.post(new Runnable()
    {
        @Override
        public void run()
        {
            mDrawerToggle.syncState();
        }
    });

    mDrawerLayout.setDrawerListener(mDrawerToggle);
}

private void selectItem(int position)
{
    mCurrentSelectedPosition = position;
    if (mDrawerListView != null)
    {
        mDrawerListView.setItemChecked(position, true);
    }
    if (mDrawerLayout != null)
    {
        mDrawerLayout.closeDrawer(mFragmentContainerView);
    }
    if (mCallbacks != null)
    {
        mCallbacks.onNavigationDrawerItemSelected(position);
    }
}

@Override
public void onAttach(Activity activity)
{
    super.onAttach(activity);
    try
    {
        mCallbacks = (NavigationDrawerCallbacks) activity;
    }
    catch (ClassCastException e)
    {
        throw new ClassCastException("Activity must implement NavigationDrawerCallbacks.");
    }
}

@Override
public void onDetach()
{
    super.onDetach();
    mCallbacks = null;
}

@Override
public void onSaveInstanceState(Bundle outState)
{
    super.onSaveInstanceState(outState);
    outState.putInt(STATE_SELECTED_POSITION, mCurrentSelectedPosition);
}

@Override
public void onConfigurationChanged(Configuration newConfig)
{
    super.onConfigurationChanged(newConfig);
    // Forward the new configuration the drawer toggle component.
    mDrawerToggle.onConfigurationChanged(newConfig);
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater)
{
    // If the drawer is open, show the global app actions in the action bar. See also
    // showGlobalContextActionBar, which controls the top-left area of the action bar.
    if (mDrawerLayout != null && isDrawerOpen())
    {
        inflater.inflate(R.menu.global, menu);
        showGlobalContextActionBar();
    }
    super.onCreateOptionsMenu(menu, inflater);
}

@Override
public boolean onOptionsItemSelected(MenuItem item)
{
    if (mDrawerToggle.onOptionsItemSelected(item))
    {
        return true;
    }

    /*
     * if (item.getItemId() == R.id.action_example)
     * {
     * Toast.makeText(getActivity(), "Example action.", Toast.LENGTH_SHORT).show();
     * return true;
     * }
     */

    return super.onOptionsItemSelected(item);
}

/**
 * Per the navigation drawer design guidelines, updates the action bar to show the global app
 * 'context', rather than
 * just what's in the current screen.
 */
private void showGlobalContextActionBar()
{
    ActionBar actionBar = getActionBar();
    actionBar.setDisplayShowTitleEnabled(true);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
    actionBar.setTitle(R.string.app_name);
}

private ActionBar getActionBar()
{
    return ((ActionBarActivity) getActivity()).getSupportActionBar();
}
}

 public class MyFragment extends Fragment implements GetActionBarTitle, OnClickListener
{
private int titleId;
private Button btn0;
private Button btn1;
private Button btn2;

public MyFragment()
{
    super();
    titleId = R.string.drawer_myfragment_title;
}

@Override
public int getActionBarTitleId()
{
    return titleId;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
    View rootView = inflater.inflate(R.layout.fragment_myfragment, container, false);
    return rootView;
}

@Override
public void onViewCreated(View view, Bundle savedInstanceState)
{
    super.onViewCreated(view, savedInstanceState);
    btn0 = (Button) view.findViewById(R.id.btn0);
    btn1 = (Button) view.findViewById(R.id.btn1);
    btn2 = (Button) view.findViewById(R.id.btn2);

    btn0.setOnClickListener(this);
    btn1.setOnClickListener(this);
    btn2.setOnClickListener(this);
}

@Override
public void onClick(View v)
{
    if (btn0 == v)
    {

    }
    else if (btn1 == v)
    {

    }
    else if (btn2 == v)
    {

    }
}
}

@Override
public void onNavigationDrawerItemSelected(int position) {
    // update the main content by replacing fragments

    FragmentManager fragmentManager = getSupportFragmentManager();

    if (position == 0) {  
        fragmentManager.beginTransaction() 
             .replace(R.id.container, FirstFragment.newInstance())  
             .commit();  
    } else if (position == 1) {  
       fragmentManager.beginTransaction()  
         .replace(R.id.container, SecondFragment.newInstance())  
         .commit();  
    } else if (position == 2) {  
       fragmentManager.beginTransaction()  
         .replace(R.id.container, ThridFragment.newInstance())  
         .commit();  
    }  

}

public class FirstFragment extends Fragment {  

   public static FirstFragment newInstance() {
     FirstFragment fragment = new FirstFragment();  
     return fragment;  
   }  

   public FirstFragment() {  
   }  

   @Override  
   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {  
       View rootView = inflater.inflate(R.layout.fragment_first, container, false);  
       return rootView;  
   }  

   @Override  
   public void onAttach(Activity activity) {  
       super.onAttach(activity);  
       ((MainActivity) activity).onSectionAttached(1);  
   }  
}