Java 无法在下一屏幕上看到汉堡菜单

我在下一个活动中找不到汉堡包菜单。它显示操作栏，但不显示汉堡包菜单。我正在使用Android Studio IDE

MainActivity.java

public class MainActivity extends ActionBarActivity {
    private DrawerLayout mDrawerLayout;
    private ListView mDrawerList;
    private ActionBarDrawerToggle mDrawerToggle;

    // nav drawer title
    private CharSequence mDrawerTitle;

    // used to store app title
    private CharSequence mTitle;

    // slide menu items
    private String[] navMenuTitles;
    private TypedArray navMenuIcons;

    private ArrayList<NavDrawerItem> navDrawerItems;
    private NavDrawerListAdapter adapter;

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

        mTitle = mDrawerTitle = getTitle();

        // load slide menu items
        navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);

        // nav drawer icons from resources

        navMenuIcons = getResources().obtainTypedArray(R.array.nav_drawer_icons);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.list_slidermenu);


        /**
         * Creating all buttons instances
         * */
        // Dashboard News feed button
        Button btn_newsfeed = (Button) findViewById(R.id.btn_news_feed);

        // Dashboard Friends button
        Button btn_friends = (Button) findViewById(R.id.btn_friends);

        // Dashboard Messages button
        Button btn_messages = (Button) findViewById(R.id.btn_messages);

        // Dashboard Places button
        Button btn_places = (Button) findViewById(R.id.btn_places);

        // Dashboard Events button
        Button btn_events = (Button) findViewById(R.id.btn_events);

        // Dashboard Photos button
        Button btn_photos = (Button) findViewById(R.id.btn_photos);

        /**
         * Handling all button click events
         * */

        // Listening to News Feed button click
        btn_newsfeed.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // Launching News Feed Screen
                Intent i = new Intent(MainActivity.this, NewsFeedActivity.class);
                startActivity(i);
            }
        });

        // Listening Friends button click
        btn_friends.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // Launching News Feed Screen
                Intent i = new Intent(MainActivity.this, FreindsActivity.class);
                startActivity(i);
            }
        });

        // Listening Messages button click
        btn_messages.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // Launching News Feed Screen
                Intent i = new Intent(MainActivity.this, MessagesActivity.class);
                startActivity(i);
            }
        });

        // Listening to Places button click
        btn_places.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // Launching News Feed Screen
                Intent i = new Intent(MainActivity.this, PlacesActivity.class);
                startActivity(i);
            }
        });

        // Listening to Events button click
        btn_events.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // Launching News Feed Screen
                Intent i = new Intent(MainActivity.this, EventsActivity.class);
                startActivity(i);
            }
        });

        // Listening to Photos button click
        btn_photos.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // Launching News Feed Screen
                Intent i = new Intent(MainActivity.this, PhotosActivity.class);
                startActivity(i);
            }
        });

        navDrawerItems = new ArrayList<NavDrawerItem>();

        // adding nav drawer items to array
        // Home
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
        // Find People
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
        // Photos
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
        // Communities, Will add a counter here
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1), true, "22"));
        // Pages
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
        // What's hot, We  will add a counter here
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1), true, "50+"));


        // Recycle the typed array
       navMenuIcons.recycle();

        mDrawerList.setOnItemClickListener(new SlideMenuClickListener());

        // setting the nav drawer list adapter
        adapter = new NavDrawerListAdapter(getApplicationContext(),navDrawerItems);
        mDrawerList.setAdapter(adapter);

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

        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
                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) {
                getSupportActionBar().setTitle(mTitle);
                // calling onPrepareOptionsMenu() to show action bar icons
                invalidateOptionsMenu();
            }

            public void onDrawerOpened(View drawerView) {
                mDrawerList.bringToFront();
                mDrawerLayout.requestLayout();
                //getSupportActionBar().setTitle(mDrawerTitle);
                // calling onPrepareOptionsMenu() to hide action bar icons
                invalidateOptionsMenu();
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);
       // mDrawerToggle.setDrawerIndicatorEnabled(false);

        if (savedInstanceState == null) {
            // on first time display view for first nav item
            displayView(0);
        }
    }

    /**
     * Slide menu item click listener
     * */
    private class SlideMenuClickListener implements
            ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                                long id) {

            switch(position) {
                case 1:
                    Intent a = new Intent(MainActivity.this, NewsFeedActivity.class);
                    startActivity(a);
                    break;
                case 2:
                    Intent b = new Intent(MainActivity.this, FreindsActivity.class);
                    startActivity(b);
                    break;
                case 3:
                    Intent c = new Intent(MainActivity.this, MessagesActivity.class);
                    startActivity(c);
                    break;
                case 4:
                    Intent d = new Intent(MainActivity.this, PlacesActivity.class);
                    startActivity(d);
                    break;
                case 5:
                    Intent e = new Intent(MainActivity.this, EventsActivity.class);
                    startActivity(e);
                    break;
                case 6:
                    Intent f = new Intent(MainActivity.this, PhotosActivity.class);
                    startActivity(f);
                    break;

                default:
            }
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // toggle nav drawer on selecting action bar app icon/title
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        // Handle action bar actions click
        switch (item.getItemId()) {
            case R.id.action_settings:
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    /***
     * Called when invalidateOptionsMenu() is triggered
     */
    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // if nav drawer is opened, hide the action items
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
        menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
        return super.onPrepareOptionsMenu(menu);
    }

    /**
     * Diplaying fragment view for selected nav drawer list item
     * */
    private void displayView(int position) {
        // update the main content by replacing fragments
        Fragment fragment = null;
        switch (position) {
            case 0:
                fragment = new HomeFragment();
                break;
            case 1:
                fragment = new FindPeopleFragment();
                break;
            case 2:
                fragment = new PhotosFragment();
                break;
            case 3:
                fragment = new CommunityFragment();
                break;
            case 4:
                fragment = new PagesFragment();
                break;

            default:
                break;
        }

        if (fragment != null) {
            FragmentManager fragmentManager = getFragmentManager();
            fragmentManager.beginTransaction()
                    .replace(R.id.frame_container, fragment).commit();

            // update selected item and title, then close the drawer
            mDrawerList.setItemChecked(position, true);
            mDrawerList.setSelection(position);
            setTitle(navMenuTitles[position]);
            mDrawerLayout.closeDrawer(mDrawerList);
        } else {
            // error in creating fragment
            Log.e("MainActivity", "Error in creating fragment");
        }
    }

    @Override
    public void setTitle(CharSequence title) {
        mTitle = title;
        getSupportActionBar().setTitle(mTitle);
    }

    /**
     * When using the ActionBarDrawerToggle, you must call it during
     * onPostCreate() and onConfigurationChanged()...
     */

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

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Pass any configuration change to the drawer toggls
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

    public void onBackPressed() {

        AlertDialog.Builder alertDlg = new AlertDialog.Builder(this);


        alertDlg.setMessage("Are you sure you want to exit?");

        alertDlg.setCancelable(false);


        alertDlg.setPositiveButton("Yes", new DialogInterface.OnClickListener() {


                    public void onClick(DialogInterface dialog, int id) {

                        MainActivity.super.onBackPressed();

                    }

                }

        );

        alertDlg.setNegativeButton("No", new DialogInterface.OnClickListener() {

            @Override

            public void onClick(DialogInterface dialog, int which) {

                // We do nothing

            }

        });

        alertDlg.create().show();
    }

}

---

您必须在第一个活动中编写创建汉堡包的所有代码，在第二个活动中也是如此。只是当你添加的时候会有所不同

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

---

你们得到的是返回箭头，而不是第一个活动中的三条水平线。

下一个活动是什么意思？

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