Android Program Development: (5) screen components-5.2 LinearLayout linear Layout

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

 

1. <? Xml version = "1.0" encoding = "UTF-8"?>
2. <LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android"
3. Android: layout_width = "fill_parent"
4. Android: layout_height = "fill_parent"
5. Android: orientation = "vertical">
7. <TextView
8. Android: layout_width = "fill_parent"
9. Android: layout_height = "wrap_content"
10. Android: text = "@ string/hello"/>
12. </LinearLayout>

In main. xnl, the root node element is <LinearLayout>, which contains a <TextView> element. The <LinearLayout> element controls the order of views it contains.

Each View and ViewGroup have some common attributes. For example:

 

Attribute	Description
Layout_width	Specify the width of the View or ViewGroup.
Layout_height	Height of a View or ViewGroup
Layout_marginTop	Extra space above the View or ViewGroup
Layout_marginBottom	Specify additional space under the View or ViewGroup
Layout_marginLeft	Extra space on the left side of the View or ViewGroup
Layout_marginRight	Extra space on the right of the View or ViewGroup
Layout_gravity	Specify the position of the child views in the View or ViewGroup.
Layout_weight	Extra space size assigned to View or ViewGroup
Layout_x	X coordinate of the View or ViewGroup
Layout_y	Y coordinate of View or ViewGroup

For example, the <TextView> element uses the fill_parent constant, so the width fills the width of the layout where the entire element is located. Its height is set to the constant wrap_content, which means that its height will be the same as its layout. If you do not want <TextView> to occupy the entire screen, you can set the layoutt_width element to wrap_content, just like this:

 

1. <TextView
2. Android: layout_width = "wrap_content"
3. Android: layout_height = "wrap_content"
4. Android: text = "@ string/hello"/> <span style = "font-family: Arial, Helvetica, sans-serif;">
5. </Span> www.2cto.com

The preceding Code sets the TextView width to the same length as the text contained in the TextView.

See the following layout:

 

1. <? Xml version = "1.0" encoding = "UTF-8"?>
2. <LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android"
3. Android: layout_width = "fill_parent"
4. Android: layout_height = "fill_parent"
5. Android: orientation = "vertical">
7. <TextView
8. Android: layout_width = "100dp"
9. Android: layout_height = "wrap_content"
10. Android: text = "@ string/hello"/>
12. <Button
13. Android: layout_width = "160dp"
14. Android: layout_height = "wrap_content"
15. Android: text = "Button"/>
17. </LinearLayout>

Here, the TextView and Button width are set to a fixed value.
From manoel's column