Android LayoutInflater.inflate(int resource, ViewGroup root, boolean attachToRoot)的参数理解

方法inflate(int resource, ViewGroup root, boolean attachToRoot) 中

第一个参数传入布局的资源ID，生成fragment视图，第二个参数是视图的父视图，通常我们需要父
视图来正确配置组件。第三个参数告知布局生成器是否将生成的视图添加给父视图。

我们新建一个项目测试一下：

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
 
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="helloworld" />
   
    <FrameLayout
        android:id="@+id/framelayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        
    </FrameLayout>
 
</LinearLayout>

 

fragment_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
 
    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" />
 
</LinearLayout>

 

MainActivity.java：第一种情况没有attachToRoot参数，默认告知布局生成器将生成的视图添加给父视图，

 1 public class MainActivity extends Activity {
 2 
 3     @Override
 4     protected void onCreate(Bundle savedInstanceState) {
 5         super.onCreate(savedInstanceState);
 6         setContentView(R.layout.activity_main);
 7         ViewGroup vg = (ViewGroup) findViewById(R.id.framelayout);
 8         View v  = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg);
 9 //      View v = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg, false);
10 //      View v = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg, true);
11         
12       
13     }
14 
15    
16 }

第二种情况：参数attachToRoot设为false，不将生成的视图（fragmnt_main）添加给父视图(activity_main)，

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ViewGroup vg = (ViewGroup) findViewById(R.id.framelayout);
//        View v  = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg);
          View v = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg, false);
//        View v = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg, true);
    }
}

 

第三种情况：参数attachToRoot设为true，将生成的视图（fragmnt_main）添加给父视图(activity_main)，

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ViewGroup vg = (ViewGroup) findViewById(R.id.framelayout);
//        View v  = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg);
//        View v = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg, false);
          View v = LayoutInflater.from(this).inflate(R.layout.fragment_main, vg, true);
    }
}