Three properties are used to fit the horizontal or vertical size of the view, and a layout based on the contents or dimensions of the view is more convenient than specifying the view range precisely.
(1) fill_parent
Setting the layout of a component to fill_parent will force the component to expand to fill as much space as possible within the layout unit. This is roughly the same as the DockStyle property of Windows controls. Setting a top layout or control for Fill_parent will force it to fill the entire screen.
(2) Wrap_content
Setting the size of a view to Wrap_content will force the view to expand to show the entire content. Take the TextView and ImageView controls as an example, set to Wrap_content to fully display the text and images inside them. Layout elements will change size based on content. Setting the size of a view to Wrap_content is roughly equivalent to setting the AutoSize property of Windows controls to true.
(3) Match_parent
Android2.2 in Match_parent and fill_parent is a meaning. Two parameters meaning, match_parent more appropriate, so starting from 2.2 two words can be used. So if you consider the use of the lower version, you need to use fill_parent.
The difference between Android layouts Fill_parent, wrap_content, and Match_parent