Question

我已经创建了一个实现此方法的NavigationDrawerFragment。

 public static interface NavigationDrawerCallbacks {
    /**
     * Called when an item in the navigation drawer is selected.
     */
    void onNavigationDrawerItemSelected(int position);
}

当我尝试定义我的方法时，它从未被调用过。我试图在NavigationDrawerCallbacks内定义它，但它会显示一条错误消息（NavigationDrawerCallbacks不应该有一个团队）。这是我的方法：

public void onNavigationDrawerItemSelected(int position) {
    // update the main content by replacing fragments
    Fragment fragment = new SpotFragement();
    FragmentManager fragmentManager = getFragmentManager();
    switch(position) {
        case 0:
            fragment = new SpotFragement();
            break;
        case 1:
            fragment = new SessionsFragement();
            break;
    }
    fragmentManager.beginTransaction()
            .replace(R.id.container, fragment)
            .commit();
}

所以任何人都有任何想法？非常感谢。

更新：

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;

private Context context;

TextView textView;

public NavigationDrawerFragment() {
}

@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);
        }
    });

    //Set Black Color for the text

   /* textView=(TextView) getText(android.R.id.text1);
    textView.setTextColor(getResources().getColor(R.color.dark_grey));
    textView.setTypeface(Typeface.DEFAULT_BOLD);
    textView.setTextSize((float) 20);*/

    mDrawerListView.setAdapter(new ArrayAdapter<String>(getActionBar().getThemedContext(), android.R.layout.simple_list_item_1, android.R.id.text1,
            new String[] {
                    getString(R.string.title_section1),
                    getString(R.string.title_section2),
                    getString(R.string.title_section3),
                    getString(R.string.title_section4),
                    getString(R.string.title_section5),
                    getString(R.string.title_section6)}) {

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            TextView textView = (TextView) super.getView(position, convertView, parent);
            textView.setTextColor(getResources().getColor(R.color.dark_grey));

            //To Set the icones
            Drawable image = getResources().getDrawable(R.drawable.spots);
            Drawable image2 = getResources().getDrawable(R.drawable.sessions);

            textView.setCompoundDrawablesWithIntrinsicBounds( image, null, null, null);

            return textView;
        }
    });

    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();
}

/**
 * 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);
}

}

Answer 1

实施界面，然后

**@Override**
public void onNavigationDrawerItemSelected(int position) {
// update the main content by replacing fragments
Fragment fragment = new SpotFragement();
FragmentManager fragmentManager = getFragmentManager();
switch(position) {
    case 0:
        fragment = new SpotFragement();
        break;
    case 1:
        fragment = new SessionsFragement();
        break;
}
fragmentManager.beginTransaction()
        .replace(R.id.container, fragment)
        .commit();
}

这部分代码

if (mCallbacks != null) {
    mCallbacks.onNavigationDrawerItemSelected(position);
}

将调用此部分代码

public void onNavigationDrawerItemSelected(int position) {
// update the main content by replacing fragments
Fragment fragment = new SpotFragement();
FragmentManager fragmentManager = getFragmentManager();
switch(position) {
    case 0:
        fragment = new SpotFragement();
        break;
    case 1:
        fragment = new SessionsFragement();
        break;
}
fragmentManager.beginTransaction()
        .replace(R.id.container, fragment)
        .commit();
}

但是只有实现接口并覆盖方法！这是因为接口实例属于该活动 - ＆gt;

Callbacks = (NavigationDrawerCallbacks) activity;

如何正确添加onNavigationDrawerItemSelected方法？

1 个答案: