Question

我正在使用一个主要活动和多个片段创建一个Android应用。我正在使用导航抽屉里面有两个项目 - 片段A和片段B.从片段A你可以去2个低级片段和片段B相同。在我的例子中，片段B.1中有一个按钮，片段B.2允许您直接进入片段A.3。（见下图）

这一切都适用于后端堆栈，但我想实现主页上升按钮。通常，如果您使用多个活动，则可以使用NavUtils类，但我不能将其用于片段。相反，我已经实现了找到here的解决方案。不幸的是，在我的情况下，这并没有正确地遵循导航模式，因为当我点击片段B.2中的按钮转到片段A.3然后单击向上按钮它将我带回片段B.2而不是向上片段A.2。

我所说的导航模式如下所示： i.stack.imgur.com/EsoTl.png

我的应用导航如下所示： i.stack.imgur.com/8WjBr.png

代码：

private FragmentManager.OnBackStackChangedListener
        mOnBackStackChangedListener = new FragmentManager.OnBackStackChangedListener() {
    @Override
    public void onBackStackChanged() {
        setActionBarArrowDependingOnFragmentsBackStack();
    }
};


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

    // get the title of the current page
    title = drawerTitle = getTitle();

    // load slide menu item titles
    navMenuTitles = getResources().getStringArray(R.array.nav_menu_items);

    navMenuLayout = (DrawerLayout) findViewById(R.id.nav_menu_layout);
    navMenuList = (ListView) findViewById(R.id.nav_menu_list);

    navMenuItems = new ArrayList<NavMenuItem>();

    // Instantiate a NavMenuItem object and add it to an ArrayList.
    for (int i = 0; i < navMenuTitles.length; i++){
        navMenuItems.add(new NavMenuItem(navMenuTitles[i]));
    }

    // setting the nav menu list adapter
    adapter = new NavMenuListAdapter(getApplicationContext(),navMenuItems);
    navMenuList.setAdapter(adapter);

    // enabling action bar app icon and behaving it as toggle button
    getActionBar().setDisplayHomeAsUpEnabled(true);
    getActionBar().setHomeButtonEnabled(true);

    // setup the onItemClickListener to load correct page when user clicks on navigation item
    navMenuList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            displayFragment(position);

        }
    });


    mDrawerToggle = new ActionBarDrawerToggle(this, navMenuLayout,
            R.drawable.ic_drawer, //nav menu toggle icon
            R.string.app_name, // nav drawer open - description for accessibility
            R.string.app_name // nav drawer close - description for accessibility
    ){
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(title);
        }

        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(drawerTitle);
        }
    };

    navMenuLayout.setDrawerListener(mDrawerToggle);
    getSupportFragmentManager().addOnBackStackChangedListener(mOnBackStackChangedListener);

    // if this is the first time the app is being opened then open the first page from the list.
    if (savedInstanceState == null) {
        // on first time display view for first nav item
        displayFragment(0);
    }

}

@Override
protected void onDestroy() {
    getSupportFragmentManager().removeOnBackStackChangedListener(mOnBackStackChangedListener);
    super.onDestroy();
}

private void setActionBarArrowDependingOnFragmentsBackStack() {
    int backStackEntryCount =
            getSupportFragmentManager().getBackStackEntryCount();
    mDrawerToggle.setDrawerIndicatorEnabled(backStackEntryCount == 0);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    if (mDrawerToggle.isDrawerIndicatorEnabled() &&
            mDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    } else if (item.getItemId() == android.R.id.home &&
            getSupportFragmentManager().popBackStackImmediate()) {
        return true;
    } else {
        switch (item.getItemId()) {
                // handle other items in actionbar
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}

使用片段向后导航

0 个答案: