工具栏（后退按钮不显示）

Question

我复制了Universal Image Loader的代码并做了一些调整。
但是，当我把我的工具栏，后面的导航不显示。
这是代码。
而且我也可以使用UIL多重选择图像？
谢谢。

package com.thesis.juandirection.juandirectionfinale; 

import android.content.Intent; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 

import com.thesis.juandirection.juandirectionfinale.fragments.ImageGridFragment; 
import com.thesis.juandirection.juandirectionfinale.fragments.ImageListFragment; 
import com.thesis.juandirection.juandirectionfinale.fragments.ImageGalleryFragment; 
import com.thesis.juandirection.juandirectionfinale.fragments.ImagePagerFragment; 
import com.thesis.juandirection.juandirectionfinale.review.reviewView; 

public class SimpleImageActivity extends AppCompatActivity{ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.fr_image_grid); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.app_bar); 
     setSupportActionBar(toolbar); 
     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
     getSupportActionBar().setTitle("Review: Bulacan State University"); 
     int frIndex = getIntent().getIntExtra(Constants.Extra.FRAGMENT_INDEX, 0); 
     Fragment fr; 
     String tag; 
     int titleRes; 
     switch (frIndex) { 
      default: 
      case ImageListFragment.INDEX: 
       tag = ImageListFragment.class.getSimpleName(); 
       fr = getSupportFragmentManager().findFragmentByTag(tag); 
       if (fr == null) { 
        fr = new ImageListFragment(); 
       } 
       titleRes = R.string.ac_name_image_list; 
       break; 
      case ImageGridFragment.INDEX: 
       tag = ImageGridFragment.class.getSimpleName(); 
       fr = getSupportFragmentManager().findFragmentByTag(tag); 
       if (fr == null) { 
        fr = new ImageGridFragment(); 
       } 
       titleRes = R.string.ac_name_image_grid; 
       break; 
      case ImagePagerFragment.INDEX: 
       tag = ImagePagerFragment.class.getSimpleName(); 
       fr = getSupportFragmentManager().findFragmentByTag(tag); 
       if (fr == null) { 
        fr = new ImagePagerFragment(); 
        fr.setArguments(getIntent().getExtras()); 
       } 
       titleRes = R.string.ac_name_image_pager; 
       break; 
      case ImageGalleryFragment.INDEX: 
       tag = ImageGalleryFragment.class.getSimpleName(); 
       fr = getSupportFragmentManager().findFragmentByTag(tag); 
       if (fr == null) { 
        fr = new ImageGalleryFragment(); 
       } 
       titleRes = R.string.ac_name_image_gallery; 
       break; 
     } 

     setTitle(titleRes); 

     getSupportFragmentManager().beginTransaction().replace(android.R.id.content, fr, tag).commit(); 

    } 

    /*public void goBack(View view){ 
     startActivity(new Intent(getApplicationContext(), reviewView.class)); 
    }*/ 
} 

XML ..

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout 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/drawer_layout" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <FrameLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:fitsSystemWindows="true"> 


     <RelativeLayout 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:background="@color/white" 
      tools:context="com.example.directioner.newjd.MainActivity"> 

      <include 
       android:id="@+id/app_bar" 
       layout="@layout/app_bar" /> 
      <GridView xmlns:android="http://schemas.android.com/apk/res/android" 
       android:id="@+id/grid" 
       android:layout_below="@+id/app_bar" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:gravity="center" 
       android:horizontalSpacing="4dip" 
       android:numColumns="3" 
       android:padding="4dip" 
       android:stretchMode="columnWidth" 
       android:verticalSpacing="4dip" /> 


     </RelativeLayout> 
    </FrameLayout> 
</RelativeLayout> 

我AndroidManifest。

<activity 
      android:name=".SimpleImageActivity" 
      android:label="@string/title_activity_simple_image" 
      android:theme="@style/AppTheme" > 
      <meta-data 
       android:name="android.support.PARENT_ACTIVITY" 
       android:value=".review.reviewView" /> 
     </activity> 

我错过了什么？ 在此先感谢，

Answer 1

你错过了getSupportActionBar（）。setHomeButtonEnabled（true）。欲了解更多信息请通过Adding backbutton on top of child element of Toolbar