导航抽屉活动Android Studio

在Android Studio中，对于导航抽屉活动，有一个三行符号，单击该符号后，屏幕左侧将显示导航抽屉菜单。这个三行符号叫什么

另外，如何让这个三行符号出现在屏幕上

请帮忙

private ActionBarDrawerToggle toggle;
private DrawerLayout drawer;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_side_options);

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

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

    drawer.addDrawerListener(toggle);
    toggle.syncState();
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    //getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    //getSupportActionBar().setHomeButtonEnabled(true);
    //getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_menu_camera);

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

@Override
public void onBackPressed() {
    drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.side_options, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    if (toggle.onOptionsItemSelected(item)) {
        return true;
    }

    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    /* if (id == R.id.action_settings) {
        return true;
    } */

    return super.onOptionsItemSelected(item);
}

---

称为汉堡图标的三行符号

private DrawerLayout mdrawerLayout;
    private ActionBarDrawerToggle mToogle;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_account);
 mdrawerLayout = (DrawerLayout) findViewById(R.id.drawer_Layout);
        mToogle = new ActionBarDrawerToggle(this, mdrawerLayout, R.string.navigation_drawer_open, R.string.navigation_drawer_close);

        mdrawerLayout.addDrawerListener(mToogle);
        mToogle.syncState();

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    public boolean onOptionsItemSelected(MenuItem Item){

        if (mToogle.onOptionsItemSelected(Item)) {

            return true;
        }

        return super.onOptionsItemSelected(Item);

            }

---

将此添加到java文件中

添加此代码以获取该图标

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

或者您也可以按以下操作

right click on package name>New>Activity>Naviagation Drawer Activity

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汉堡图标！！！我已经有了这个代码，但它仍然不起作用…换句话说，图标仍然没有显示。Sunil P，我已经有了这个代码片段，但图标仍然没有出现…好的，开始我的第二个解决方案，图标将自动出现这就是我最初做的原因（右键单击软件包…）。执行此操作后，您共享的代码已作为默认代码的一部分提供。如果这是有意义的…哈，如果该代码是默认来的图标将是可见的，我猜