(5) Android layout control

First, LinearLayout (linear layout)

One of the most commonly used layouts, the characteristic of a linear layout is that each control adds a row below the previous control by default.

<LinearLayoutxmlns:android= "Http://schemas.android.com/apk/res/android"Xmlns:tools= "Http://schemas.android.com/tools"Android:id= "@+id/linearlayout1"<!--layout's width attributes are: "Fill_parent", "Wrap_content", "match_parent"--><!--Fill_parent and Match_parent will enforce the view to the parent element size -<!--Wrap_content will fully display the text and images inside it -android:layout_width= "match_parent" android:layout_height= "Match_parent "<!--vertical Vertical, horizontal level -android:orientation= "Vertical"<!--How child elements are aligned in parent elements -android:gravity= "Bottom|right" >

Second, relativelayout (relative layout)

One of the most commonly used layouts, the relative layout feature is that the added space defaults to one overlay in the upper-left corner. The newly added control must specify the relative position of the other control in the property.

Third, tablelayout (table layout)

Features: A <TableRow> line with one more control column

Iv. framelayout (Frame layout)

Features: Overrides between controls. Application scenarios such as the button that appears in the middle of the screen when the video player pauses.

V. GridLayout (Grid layout)

Android4.0 introduced later. Easier to use than table layouts

1) You can set the arrangement of the components in the layout yourself
2) You can customize how many rows the grid layout has, how many columns
3) You can directly set the component to a column in a row
4) You can set the component to span several rows or columns

Typical cases, such as calculators

Vi. absolutelayout (Absolute layout)

Features: Can be dragged to the screen like WinForm, what you see is what you gain. However, when the resolution changes, the size and spacing of the controls change.

TextView

Drag the control into the phone, right-click Go to XML and see the following code

    <TextView        android:text= "TextView"        android:layout_width= "wrap_content"        android: layout_height= "Wrap_content"        android:layout_margintop= "14DP"        android:id= "@+id/textview2 " android:layout_below= "@+id/textview" android:layout_alignparentstart= "true"/>    

Android:id    Control uniquely identifies

Android:text  Display of text information

Android:layout_width Control width

Android:layout_height Control Height

Width and height There are three ways to assign values:
1. Fixed values such as 100DP can be set
2. Can also dynamically change   "Wrap_content"
3. The width and height   match_parent  fill_parent (old version) can be adapted to the parent layout





DPI = pixel density----The number of dots you can print per inch--  inches is a line
  160 dots on a 1-inch-long line, such as DPI,   dpi160 is a standard screen


px= pixels |

DP (DIP) = device Independent pixel

1dp=1px at DPI 320 under the premise of the standard DPI  1dp=2px

Summarize
The higher  The pixel density of the screen, the less it looks
Same DP  with different pixel densities, looks as long  

Reference

Android:lines= "5" shows 5 rows

(5) Android layout control