android - 如何将导航菜单更改为后退箭头？

Question

我正在创建一个使用导航菜单的应用程序。当我点击菜单时，抽屉导航打开，我点击一个项目并打开一个 fragment 。我想要这样，当 fragment 打开的导航菜单变为后退箭头时。

这是我的 Activity 代码:

public class Container_Activity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    FrameLayout frameLayout;
    private Boolean exit = false;
    FloatingActionButton floatingActionButton;

    static Container_Activity activity;

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

        if (android.os.Build.VERSION.SDK_INT >= 21) {
            Window window = this.getWindow();

            window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            window.setStatusBarColor(this.getResources().getColor(R.color.statusbarcolor));

        }
        activity = this;

        if (savedInstanceState == null) {
            Container_Activity.showFragment(new Home_fragment(), "");

        }


        frameLayout = (FrameLayout) findViewById(R.id.container_frame);
        floatingActionButton = (FloatingActionButton) findViewById(R.id.fab);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        toolbar.setNavigationIcon(getResources().getDrawable(R.drawable.ic_arrow_back));
        if (getSupportActionBar() != null) {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            getSupportActionBar().setDisplayShowHomeEnabled(true);
        }


        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        floatingActionButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Container_Activity.showFragment(new ConctactUs_fragment(), "");

            }

        });

    }

    public void showFloatingActionButton() {
        floatingActionButton.show();
    }

    ;

    public void hideFloatingActionButton() {
        floatingActionButton.hide();
    }

    ;

    @Override
    public void onBackPressed() {

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);

        } else {

            super.onBackPressed();

        }
    }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);

        switch (item.getItemId()) {

            case R.id.home_item:

                showFragment(new Home_fragment(), "Home");

                break;
            case R.id.services:

                showFragment(new Services_fragment(), "Services");
                break;
            case R.id.portfolio_item:

                showFragment(new Portfolio_fragment(), "Portfolio");
                break;
            case R.id.training_item:

                showFragment(new Training_fragment(), "Training");
                break;
            case R.id.gallery_item:

                showFragment(new Gallery_Fragment(), "Gallery");
                break;

            case R.id.share_item:

                shareurl();
                break;
            case R.id.reach_us:

                showFragment(new ConctactUs_fragment(), "Contact");
                break;
        }

        return false;
    }

    private void shareurl() {

        Intent sendIntent = new Intent();
        sendIntent.setAction(Intent.ACTION_SEND);
        sendIntent.putExtra(Intent.EXTRA_TEXT,
                "Hey check out my app at: https://play.google.com/store/apps/details?id=com.techenrage");
        sendIntent.setType("text/plain");
        startActivity(sendIntent);
    }


    public static void showFragment(Fragment fragment, String Tag) {


        FragmentManager manager = activity.getSupportFragmentManager();
        FragmentTransaction transcation = manager.beginTransaction();
        transcation.replace(R.id.container_frame, fragment, Tag);
        transcation.addToBackStack(Tag);
        transcation.commit();

    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {

        if (ev.getAction() == MotionEvent.ACTION_DOWN) {
            View v = getCurrentFocus();
            if (v instanceof EditText) {
                Rect outRect = new Rect();
                v.getGlobalVisibleRect(outRect);
                if (!outRect.contains((int) ev.getRawX(), (int) ev.getRawY())) {
                    v.clearFocus();
                    InputMethodManager imm = (InputMethodManager) getSystemService(activity.INPUT_METHOD_SERVICE);
                    imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
                }
            }
        }
        return super.dispatchTouchEvent(ev);
    }


}

fragment 类:

public class Portfolio_fragment extends Fragment {

TabLayout tabLayout;
ViewPager viewPager;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    final View view = inflater.inflate(R.layout.portfolio_fragment, container, false);

    ((AppCompatActivity) getActivity()).getSupportActionBar().setTitle("Portfolio");

    tabLayout = (TabLayout) view.findViewById(R.id.tabLayout);
    tabLayout.setupWithViewPager(viewPager);

    tabLayout.addTab(tabLayout.newTab().setText("Websites"));
    tabLayout.addTab(tabLayout.newTab().setText("Mobile Application"));
    tabLayout.addTab(tabLayout.newTab().setText("Graphics"));
    tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

    viewPager = (ViewPager) view.findViewById(R.id.portfolio_pager);

    Portfolio_Adapter adapter = new Portfolio_Adapter(getChildFragmentManager(), tabLayout.getTabCount());

    viewPager.setAdapter(adapter);

    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {

            viewPager.setCurrentItem(tab.getPosition());

        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {

        }
    });

    viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    return view;
}

Answer 1

试试这个

@Override
        protected void onCreateView(Bundle savedInstanceState) {

              ((AppCompatActivity) getActivity()).getSupportActionBar().setHomeAsUpIndicator(R.drawable.back_button);
             ((AppCompatActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        }