使用导航抽屉在片段中向上导航

Question

我想使用一个名为 MainActivity 的活动，它有一个抽屉布局和主要内容容器（使用 FrameLayout）。现在的抽屉布局只是一个普通的 ListView，现在只有两个项目。我为每个项目制作了两个片段。第一项是 Home，第二项是 Saved。 当调用 MainActivity onCreate() 时，我将容器替换为 HomeFragment，然后我可以使用 Drawer 导航到 SavedFragment。 导航完美运行，没有任何问题。 我想要实现的任务是，每当我通过单击抽屉上的第二个项目转到 SavedFragment 时，汉堡图标应更改为后退按钮/向上按钮。 我设法通过在同一问题上浏览了很多 StackOverflow 主题来更改它，但我无法在其上添加点击事件。它不听点击。我在 StackOverflow 上阅读了一些非常好的东西，并希望它也对我有用，但也许我在代码的某个地方错了。所以我在这里分享代码：

MainActivity（应用程序中的唯一Activity）代码

public class MainActivity extends ActionBarActivity implements AdapterView.OnItemClickListener {


Toolbar toolbar;
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
private ListView listView;
Fragment mFragment;
ArrayList<NavigationDataRecord> drawerRecord;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    toolbar = (Toolbar) findViewById(R.id.toolbar);
    listView = (ListView) findViewById(R.id.drawer_left);
    listView.setOnItemClickListener(this);
    drawerRecord = new ArrayList<NavigationDataRecord>();
    drawerRecord.add(new NavigationDataRecord(R.mipmap.ic_home_grey600_24dp, "Home"));
    drawerRecord.add(new NavigationDataRecord(R.mipmap.ic_save_grey600_24dp, "Saved"));
    CustomAdapter adapter = new CustomAdapter(this, R.layout.list_row, drawerRecord);
    listView.setAdapter(adapter);

    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setHomeButtonEnabled(true);


    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);

    mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, toolbar,
            R.string.app_name, R.string.app_name) {

        /** Called when a drawer has settled in a completely open state. */
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            invalidateOptionsMenu();
        }

        /** Called when a drawer has settled in a completely closed state. */
        public void onDrawerClosed(View view) {
            super.onDrawerClosed(view);
            invalidateOptionsMenu();
        }
    };


        mFragment = new HomeFragment();
        getSupportFragmentManager().beginTransaction().replace(R.id.container, mFragment).commit();

        mDrawerToggle.setDrawerIndicatorEnabled(true);
        mDrawerLayout.setDrawerListener(mDrawerToggle);


}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();

  if (id == R.id.action_settings) {
        return true;
    }

return super.onOptionsItemSelected(item);

}




@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    mDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    mDrawerToggle.onConfigurationChanged(newConfig);
}

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {



    switch (position) {
        case 0:
            mFragment = new HomeFragment();
            break;

        case 1:
            mFragment = new SavedFragment();
            break;

        default:
           break;

    }

    getSupportFragmentManager().beginTransaction().replace(R.id.container,mFragment).addToBackStack(null).commit();
    mDrawerLayout.closeDrawer(listView);

}}

保存片段代码

public class SavedFragment extends Fragment {


List<SavedInformation> list;
RecyclerView cardView;


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


}

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.saved_fragment, container, false);
    list = new ArrayList<SavedInformation>();
    makeCardList();
    cardView = (RecyclerView) view.findViewById(R.id.cardList);
    //cardView.setHasFixedSize(true);
    LinearLayoutManager llm = new LinearLayoutManager(getActivity());
    llm.setOrientation(LinearLayoutManager.VERTICAL);
    cardView.setLayoutManager(llm);
    SavedInformationAdapter adapter = new SavedInformationAdapter(list, getActivity());
    cardView.setAdapter(adapter);


    return view;
}

private void makeCardList() {
    DatabaseAdapter adapter = new DatabaseAdapter(getActivity());
    Cursor cursor = adapter.getData();

    while (cursor.moveToNext()) {
        SavedInformation information = new SavedInformation();
        information.setUsername(cursor.getString(0));
        information.setDomainName(cursor.getString(1));
        information.setImageURL(cursor.getString(2));
        list.add(information);

    }
}}

我在这些方面尝试了一些东西，但没有运气，所以我发布了我尝试实施解决方案的代码的干净版本。

我确信这些解决方案是正确的，但我无法理解为什么这些解决方案对我不起作用。

我应用了这里给出的解决方案：Switching between Android Navigation Drawer image and Up caret when using fragments

Answer 1

如果您使用的是片段，那么您必须在 MainActivity 中使用 navigateUp

@Override
public boolean onSupportNavigateUp() {
    getSupportFragmentManager().popBackStack();
    return true;
}