Toolbar的三个问题：修改左边箭头颜色、怎样修改右边以及子activity中的toolbar添加返回箭头

一、右边三个点改成其他图标

（1）通过Style设定icon

<style name="AppNabTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="actionOverflowMenuStyle">@style/OverflowMenu</item>
        <item name="windowActionModeOverlay">true</item>
        <item name="windowActionBarOverlay">true</item>
        <item name="actionModeStyle">@style/CustomActionMode</item>
        <item name="actionButtonStyle">@style/AppTheme.Widget.ActionButton</item>
        <item name="actionOverflowButtonStyle">@style/OverflowButtonStyle</item>
    </style>

    <style name="OverflowButtonStyle" parent="@android:style/Widget.ActionButton.Overflow">
        <item name="android:src">@mipmap/ic_input_add</item>
    </style>

（2）通过Menu设定icon，menu放在最后一个，总是显示

//通过Menu设定icon
//可把自带的setting设置为always,再设置icon属性

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/action_settings"
        android:icon="@drawable/search_icon"
        android:orderInCategory="100"
        android:title="@string/action_settings"
        app:showAsAction="always" />
</menu>

（3） 只修改icon颜色

In any case, it could be not a good idea to change a standard icon, like the overflow menu.
If you would like to change the color of the icon you can use:

<android.support.v7.widget.Toolbar
  app:theme="@style/ThemeToolbar" />


<style name="ThemeToolbar" parent="Theme.AppCompat.Light">

   <!-- navigation icon color -->
   <item name="colorControlNormal">@color/my_color</item>

    <!-- color of the menu overflow icon -->
    <item name="android:textColorSecondary">@color/my_color</item>
</style>

二、 左边箭头显示加上这句代码

getSupportActionBar().setDisplayHomeAsUpEnabled(true); 

      //想要响应这个返回时, 其实就是onOptionsItemSelected（）通过android.R.id.home监听得到  
      @Override  
        public boolean onOptionsItemSelected(MenuItem item) {  
            if(item.getItemId() == android.R.id.home){  
                onBackPressed();  
            }  
            return true;  
        }

从MainActivity中进入一个子activity中之后,如何使toolbar中左边显示一个返回箭头,点击后返回到Mainactivity中呢?其实很简单,只需要两行代码.

• AndroidManifest.xml中给需要在toolbar上增加返回按钮的activity增加属性

Android:parentActivityName=”com.example.myfirstapp.MainActivity”

<application ... >  
        ...  
        <!-- The main/home activity (it has no parent activity) -->  
        <activity  
            android:name="com.example.myfirstapp.MainActivity" ...>  
            ...  
        </activity>  
        <!-- A child of the main activity -->  
        <activity  
            android:name="com.example.myfirstapp.DisplayMessageActivity"  
            android:label="@string/title_activity_display_message"  
            android:parentActivityName="com.example.myfirstapp.MainActivity" >  
            <!-- Parent activity meta-data to support 4.0 and lower -->  
            <meta-data  
                android:name="android.support.PARENT_ACTIVITY"  
                android:value="com.example.myfirstapp.MainActivity" />  
        </activity>  
    </application>

• 然后再在程序里添加一行代码就实现了

@Override  
    public void onCreate(Bundle savedInstanceState) {  
        ...  
        getActionBar().setDisplayHomeAsUpEnabled(true);  
    }