Android中AppCompatActivity的操作栏中缺少打开导航抽屉的图标

Question

我正在尝试将Android导航抽屉与AppCompatActivity的操作栏一起使用。 但是，当我实现操作栏时，其中没有打开导航抽屉的图标。

这就是我想要显示的

这是我当前操作栏的屏幕截图

您可以在下面看到我的代码。

这是我的activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- This LinearLayout represents the contents of the screen  -->

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <!-- The ActionBar displayed at the top -->
        <include
            layout="@layout/action_bar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <!-- The main content view where fragments are loaded -->
        <FrameLayout
            android:id="@+id/main_content"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </LinearLayout>

    <!-- The navigation drawer that comes from the left -->
    <!-- Note that `android:layout_gravity` needs to be set to 'start' -->
    <android.support.design.widget.NavigationView
        android:id="@+id/nvView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@android:color/white"/>
        <!--app:headerLayout="@layout/nav_header"
        app:menu="@menu/drawer_view" />-->

</android.support.v4.widget.DrawerLayout>

这是我的action_bar.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:android="http://schemas.android.com/apk/res/android">

</android.support.v7.widget.Toolbar>

这是我的MainActivity

package com.blog.waiyanhein.llks.llks;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, 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.
        int id = item.getItemId();

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

        return super.onOptionsItemSelected(item);
    }
}

为什么使用我的代码缺少打开导航抽屉的图标？

Answer 1

试试这个代码，

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

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

Answer 2

我猜你没有在Activity实现NavigationDrawer 。我遇到了同样的问题，并使用以下代码修复了该问题。

在您的Activity ：

private DrawerLayout drawerLayout;

在您的onCreate ：

NavigationView navigationView = (NavigationView) findViewById(R.id.navigation_view);
    navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(MenuItem menuItem) {

            if (menuItem.isChecked()) menuItem.setChecked(false);
            else menuItem.setChecked(true);
            drawerLayout.closeDrawers();
            switch (menuItem.getItemId()) {

                case R.id.home:
                    drawerLayout.closeDrawers();
                    return true;
                default:
                    return true;

            }
        }
    });

    drawerLayout = (DrawerLayout) findViewById(R.id.drawer);
    ActionBarDrawerToggle actionBarDrawerToggle =
            new ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.openDrawer, R.string.closeDrawer) {

                @Override
                public void onDrawerClosed(View drawerView) {
                    super.onDrawerClosed(drawerView);
                }

                @Override
                public void onDrawerOpened(View drawerView) {
                    super.onDrawerOpened(drawerView);
                }
            };

    drawerLayout.setDrawerListener(actionBarDrawerToggle);
    actionBarDrawerToggle.syncState();

Strings.xml：

    <string name="openDrawer">Navigation</string>
    <string name="closeDrawer">Close Navigation</string>

然后它应该工作。

Answer 3

您可能需要包括：

actionBarDrawerToggle.syncState();

这里的答案可能会有所帮助：

Appcompatv7-v21导航抽屉不显示汉堡图标