导航抽屉汉堡包图标不显示与v7 ActionBarDrawerToggle

Question

我一直在尝试为现有的应用程序创建一个导航抽屉。我已经找到了一些教程，但其中大多数(包括官方Android指南)似乎是为v4 ActionBarDrawerToggle库，这已被弃用。我试图使用v7库代替，但我的ActionBarDrawerToggle似乎不做什么文档说它应该做的。

编辑:根据下面的答案修改了我的代码。汉堡图标现在可以正确地来回切换，但当用户点击硬件返回按钮返回到应用的主要部分时，汉堡图标就完全消失了。为什么会发生这种情况?

private void addDrawerItems() {
    String[] itemArray = {"About", "Nearby", "Settings", "Feedback",};
    mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, itemArray);
    mDrawerList.setAdapter(mAdapter);
    mDrawerList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Log.d("ContributionsActivity", "Item " + position + " selected");
        }
    });
}
private void setupDrawer() {
    mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.string.drawer_open, R.string.drawer_close) {
        /** Called when a drawer has settled in a completely open state. */
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }
        /** Called when a drawer has settled in a completely closed state. */
        public void onDrawerClosed(View view) {
            super.onDrawerClosed(view);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }
    };
    mDrawerToggle.setDrawerIndicatorEnabled(true);
    mDrawerLayout.setDrawerListener(mDrawerToggle);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setTitle(R.string.title_activity_contributions);
    setContentView(R.layout.activity_contributions);
    //Set up navigation drawer
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setHomeButtonEnabled(true);
    mDrawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout);
    mDrawerList = (ListView)findViewById(R.id.drawer_list);
    addDrawerItems();
    setupDrawer();
    ...
    }
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // enabling drawer toggle by clicking on the app icon.
    if (mDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    } else {
        switch (item.getItemId()) {
            case android.R.id.home:
                if (mediaDetails.isVisible()) {
                    getSupportFragmentManager().popBackStack();
                }
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    // Sync the toggle state after onRestoreInstanceState has occurred.
    mDrawerToggle.syncState();
}

Answer 1

@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    // Sync the toggle state after onRestoreInstanceState has occurred.
    mDrawerToggle.syncState();
}

你缺少同步状态，添加它，一切都会好的。