我已成功确定要在汉堡包和箭头之间更改 NavDrawer 中的图标，需要切换此代码:

mDrawerToggle.syncState();

但是，当我确实想返回到上一个 Activity 时，当我单击后退按钮时它仍在打开抽屉导航。

我知道我可以简单地设置一个 onClickListener，但我认为 Android 有一种更原生的导航到上一个屏幕的方式。这是我的代码:'

创建时:

    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            mDrawerLayout,         /* DrawerLayout object */
            toolbar,  /* nav drawer icon to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description */
            R.string.drawer_close  /* "close drawer" description */
    ) {

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

        /**
         * Called when a drawer has settled in a completely open state.
         */
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            isOpen = true;
        }
    };
    mDrawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            onBackPressed();
        }
    });
    mDrawerToggle.setDrawerIndicatorEnabled(false);
    mDrawerLayout.addDrawerListener(mDrawerToggle);

    mDrawerList = (ListView) findViewById(R.id.left_drawer);
    ArrayList<String> drawerTitleArray = new ArrayList<>();
    drawerTitleArray.add(0, "TEST");
    drawerTitleArray.add(1, "TEST 1");
    // Set the adapter for the list view
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, drawerTitleArray));


       // TODO: Add Fragment Code to check if savedInstanceState ==                                 null; add at Activity Level?
    // Check that the activity is using the layout version with
    // the fragment_container FrameLayout


    //set up viewpager for current day
    //mPager = (ViewPager)               findViewById(R.id.home_polls_viewpager_fragment_container);
    //mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
    //mPager.setAdapter(mPagerAdapter);


    //get current date to apply to Viewpager
    mDateFormat = new SimpleDateFormat("MM-dd-yyyy");
    mDate = new Date();
    mCurrentDateString = mDateFormat.format(mDate);
    mViewPager = (ViewPager) findViewById(R.id.poll_fragment_container);
    mViewPager.setAdapter(new SectionPagerAdapter(getSupportFragmentManager()));
    mTabLayout.setupWithViewPager(mViewPager);

    // TODO: Checkn if AuthStateListenerNecessary
    //Determine whether necessary to use an AuthStateListener here
    // mUserRef.addAuthStateListener(new Firebase.AuthStateListener() {
    //@Override
    //public void onAuthStateChanged(AuthData authData) {
    //if (authData == null) {
    //Intent backToSignIn = new Intent(getApplication(),       SignupActivity.class);
    //startActivity(backToSignIn);
    //                    finish();
    //                }
    //            }
    //        })




}

@Override
protected void onStart() {
    super.onStart();

    v = new ValueEventListener() {
        //testing methodology of adding children
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            int pollsAvailable = (int) dataSnapshot.child(mCurrentDateString).getChildrenCount();
       //                mPagerAdapter.setPollsAvailable(pollsAvailable);
            Log.i("TAG", "There are " + String.valueOf(pollsAvailable) + " children in today's poll count.");
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    };

    mPollsRef.addValueEventListener(v);

}

@Override
protected void onStop() {
    super.onStop();
    mPollsRef.removeEventListener(v);

}

@Override
public void onFragmentInteraction(Uri uri) {

}

@Override
public boolean onOptionsItemSelected(MenuItem item){
    if (item.getItemId() == android.R.id.home){
        super.onBackPressed();
        return true;}
    else
        return mDrawerToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
}



@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    //TODO: Be sure to only allow one instance of each activity
    //TODO:Address mDrawerToggle code from StackOverflow to make sure I am correctly implementing the return to previous activity
    // Sync the toggle state after onRestoreInstanceState has occurred.
    //        mDrawerToggle.syncState();
}

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

public class SectionPagerAdapter extends FragmentPagerAdapter {

    public SectionPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        int pollIndex = mIntentFromTouch.getIntExtra("Poll_Index",0);
        switch (position) {
            case 0:
                PollFragment pollFragment = PollFragment.newInstance(pollIndex);
                return pollFragment;
            case 1:
                DiscussionFragment discussionFragment = DiscussionFragment.newInstance(pollIndex);
                return discussionFragment;
            default:
                return new PollFragment();
        }
    }

    @Override
    public int getCount() {
        return 2;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return getResources().getString(R.string.poll_text);
            case 1:
                return getResources().getString(R.string.discussion_text);
            default:
                return getResources().getString(R.string.poll_text);
        }
      }
   }


 }

最佳答案

实际上，syncState()方法确保切换器的图像与抽屉处于匹配状态，并将图像设置在 Toolbar 上/ActionBar .它不会切换抽屉/后背功能。

setDrawerIndicatorEnabled()方法就是你要找的。当指示器启用时，拨动开关操作抽屉。当它被禁用时，它会回到导航 OnClickListener ，如果你设置了一个。

要处理后退功能，请将以下内容添加到切换设置中:

mDrawerToggle.setHomeAsUpIndicator(R.drawable.abc_ic_ab_back_mtrl_am_alpha);
mDrawerToggle.setToolbarNavigationClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            onBackPressed();
        }
    }
);

然后，当您想禁用抽屉操作并允许单击切换按钮返回时，只需调用:

mDrawerToggle.setDrawerIndicatorEnabled(false);

我还要指出的是，因为您已经使用了 ActionBarDrawerToggle采用 Toolbar 的构造函数参数，Activity的 onOptionsItemSelected()单击切换时不会调用方法，mDrawerToggle.onOptionsItemSelected(item)那里不需要调用。

注意:根据您使用的支持库版本，后退箭头 Drawable资源可能被命名为 R.drawable.abc_ic_ab_back_material反而。请引用this post获取更多信息。

关于java - DrawerLayout 后退箭头功能，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38579429/