汉堡图标未显示

Question

我刚从Android Studio开始，并且I'am创建了一个汉堡图标，现在一切都很好，但是汉堡偶像不可见，菜单像预期一样关闭并打开图标不可见。任何帮助将不胜感激。

活动文件

package com.example.greyhound;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
public class MainActivity extends AppCompatActivity {
    private DrawerLayout draw ;
    ActionBarDrawerToggle toggle;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar tool = findViewById(R.id.toolbar);
        setSupportActionBar(tool);
        draw = findViewById(R.id.hamburger);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,draw,tool,R.string.open_menu,R.string.close_menu);
        draw.addDrawerListener(toggle);
        toggle.syncState();
    }
}

布局文件...

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/hamburger"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".MainActivity">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>
            <FrameLayout
                android:id="@+id/frame_container"
                android:layout_width="match_parent"
                android:layout_height="match_parent">
            </FrameLayout>   
    </LinearLayout>
    <android.support.design.widget.NavigationView
        android:id="@+id/navigation"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        app:headerLayout="@layout/menu_layer"
        app:menu="@menu/burger_menu">
    </android.support.design.widget.NavigationView> 
</android.support.v4.widget.DrawerLayout>

菜单层

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:background="@color/colorAccent">
</LinearLayout>

和样式表

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
    <style name="AppTheme.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
    </style>
</resources>

我尝试添加/删除布局文件，但问题仍然存在。我假设样式文件中的问题，所以我将" windowActionbar"设置为true，我也在这里查看。

Answer 1

在调用

之前

 toggle.syncState();

add：

 actionBar.setDisplayHomeAsUpEnabled(true); // this sets the button to the back icon
 actionBar.setHomeButtonEnabled(true); // makes it clickable
 actionBar.setHomeAsUpIndicator(R.drawable.ic_drawer);// set your own icon

希望这对您有帮助。