Getting Started with Android (v) Screen components 5.2 LinearLayout linear layouts

LinearLayout organizes views into one row or column. A child view can be arranged vertically or horizontally. To see how LinearLayout works, consider the typical mail.xml file first.

<?xml version= "1.0" encoding= "Utf-8"?> <linearlayout xmlns:android=   

 
"http://schemas.android.com/apk/" Res/android " 
    android:layout_width=" fill_parent " 
    android:layout_height=" fill_parent " 
    android:o" rientation= "vertical" >    
       
    <textview 
        android:layout_width= "Fill_parent" 
        Wrap_content " 
        android:text=" @string/hello "/>    
       
</LinearLayout>

In Main.xnl, you can see that the root node element is <linearlayout>, and it contains a <TextView> element. This <LinearLayout> element controls the order of views that it contains.

Each view and viewgroup have some common attributes, some examples:

Property	Describe
Layout_width	Specify the width of view or ViewGroup
Layout_height	Specify the height of view or ViewGroup
Layout_margintop	Specify extra space above view or ViewGroup
Layout_marginbottom	Specify additional space below view or ViewGroup
Layout_marginleft	Specify extra space to the left of view or ViewGroup
Layout_marginright	Specify additional space on the right side of view or ViewGroup
Layout_gravity	Specify the placement of child views in view or ViewGroup
Layout_weight	Specify additional space dimensions assigned to view or ViewGroup
Layout_x	Specify the X coordinate of view or viewgroup
Layout_y	Specify the y-coordinate of the view or ViewGroup

For example, the,<textview> element uses the Fill_parent constant, so the width fills the width of the entire layout. Its height is set to the Wrap_content constant, which means that its height will be the same as the layout it is in. If you don't want to <TextView> occupy the entire screen, you can set the Layoutt_width element to wrap_content, like this:

    <textview 
        android:layout_width= "wrap_content" 
        android:layout_height= "wrap_content" 
        android:text = "@string/hello"/>

The code above sets the width of the textview to the same length as the text it contains.

Please see the following layout:

<?xml version= "1.0" encoding= "Utf-8"?> <linearlayout xmlns:android=    
"http://schemas.android.com/apk/" Res/android " 
    android:layout_width=" fill_parent " 
    android:layout_height=" fill_parent " 
    android:o" rientation= "vertical" >    
       
    <textview    
        android:layout_width= "100DP" 
        android:layout_height= "WRAP_" Content " 
        android:text=" @string/hello "/>    
       
    <button    
        android:layout_width=" 160DP " 
        android: layout_height= "Wrap_content" 
        android:text= "button"/>    
       
</LinearLayout>

Here, the width of the TextView and button is set to a fixed value.

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