Android study note 08: relativelayout

Relativelayout is one of the most common layout methods in actual layout. Relativelayout can be used to set the positions of a view relative to other views. These positions can include the upper, lower, and left views. Therefore, it is more flexible than other layout methods.

Common attributes of relativelayout include:

Class 1: the property value is true or false.
Android: layout_centerhrizontal horizontally centered
Android: layout_centervertical vertical center
Android: layout_centerinparent is completely centered over the parent element
Android: layout_alignparentbottom mounts the lower edge of the parent element
Android: layout_alignparentleft: Stick the left edge of the parent element
Android: layout_alignparentright: Stick the right edge of the parent element
Android: layout_alignparenttop: top edge of the parent element
Android: layout_alignwithparentifmissing if the corresponding sibling element cannot be found, the parent element will be used as a reference object

Class 2: the property value must be the reference name "@ ID/ID-name" of the ID"
Android: layout_below is under an element
Android: layout_abve is above an element.
Android: layout_toleftof on the left of an element
Android: layout_torightof on the right of an element

Android: layout_aligntop: Align the top edge of an element with the top edge of an element.
Android: layout_alignleft: Align the left edge of an element with the left edge of an element.
Android: layout_alignbottom: the bottom edge of the current element is aligned with the bottom edge of an element.
Android: layout_alignright: the right edge of an element is aligned with the right edge of an element.

Category 3: attribute values are specific pixel values
Android: layout_marginbottom distance from the bottom edge of an element
Android: layout_marginleft distance from the left edge of an element
Android: layout_marginright distance from the right edge of an element
Android: layout_margintop distance from the edge of an element

The following is an example of relative layout.Activity_main.xml source code is as follows:

Android_relativelayout instance

 1   <  Relativelayout  Xmlns: Android  = "Http://schemas.android.com/apk/res/android" 2   Xmlns: Tools  = "Http://schemas.android.com/tools"  3   Android: layout_width  = "Match_parent"  4   Android: layout_height  = "Match_parent"   >  5       6       <! --  Center button: reference object  -->  7      <  Button  8           Android: ID  = "@ + ID/mbutton_center"  9   Android: Text  = "@ String/Center"  10   Android: layout_centerhorizontal  = "True"  11   Android: layout_centervertical  = "True"  12  Android: layout_width  = "90dp"  13   Android: layout_height  = "Wrap_content"      >          14       </  Button  >  15       16       <! --  Upper  -->  17       < Button  18           Android: ID  = "@ + ID/mbutton_abve"  19   Android: Text  = "@ String/above"  20   Android: layout_abve  = "@ ID/mbutton_center"  21   Android: layout_centerhorizontal  = "True"  22   Android: layout_width = "90dp"  23   Android: layout_height  = "Wrap_content"      >          24       </  Button  >  25       26       <! --  Lower  -->  27       <  Button 28           Android: ID  = "@ + ID/mbutton_below"  29   Android: Text  = "@ String/below"  30   Android: layout_below  = "@ ID/mbutton_center"  31   Android: layout_centerhorizontal  = "True"  32   Android: layout_width  = "90dp" 33   Android: layout_height  = "Wrap_content"      >          34       </  Button  >  35       36       <! --  Left  -->  37       <  Button  38          Android: ID  = "@ + ID/mbutton_left"  39   Android: Text  = "@ String/left"  40   Android: layout_toleftof  = "@ ID/mbutton_center"  41   Android: layout_centervertical  = "True"  42   Android: layout_width  = "120dp"  43  Android: layout_height  = "Wrap_content"      >          44       </  Button  >  45       46       <! --  Right  -->  47       <  Button  48           Android: ID = "@ + ID/mbutton_right"  49   Android: Text  = "@ String/right"  50   Android: layout_torightof  = "@ ID/mbutton_center"  51   Android: layout_centervertical  = "True"  52   Android: layout_width  = "120dp"  53   Android: layout_height = "Wrap_content"      >          54       </  Button  >      55       56       <! --  Upper left  -->  57       <  Button  58           Android: ID  = "@ + ID/mbutton_aboveandleft" 59   Android: Text  = "@ String/aboveandleft"  60   Android: layout_abve  = "@ ID/mbutton_center"  61   Android: layout_toleftof  = "@ ID/mbutton_abve"  62   Android: layout_width  = "120dp"  63   Android: layout_height  = "Wrap_content"     >          64       </  Button  >  65       66       <! --  Upper right  -->  67       <  Button  68           Android: ID  = "@ + ID/mbutton_aboveandright"  69  Android: Text  = "@ String/aboveandright"  70   Android: layout_abve  = "@ ID/mbutton_center"  71   Android: layout_torightof  = "@ ID/mbutton_abve"  72   Android: layout_width  = "120dp"  73   Android: layout_height  = "Wrap_content"     >          74       </  Button  >  75       76       <! --  Bottom left  -->  77       <  Button  78           Android: ID  = "@ + ID/mbutton_belowandleft"  79  Android: Text  = "@ String/belowandleft"  80   Android: layout_below  = "@ ID/mbutton_center"  81   Android: layout_toleftof  = "@ ID/mbutton_below"  82   Android: layout_width  = "120dp"  83   Android: layout_height  = "Wrap_content"      >         84       </  Button  >              85       86       <! --  Bottom right  -->  87       <  Button  88           Android: ID  = "@ + ID/mbutton_belowandright"  89   Android: Text = "@ String/belowandright"  90   Android: layout_below  = "@ ID/mbutton_center"  91   Android: layout_torightof  = "@ ID/mbutton_below"  92   Android: layout_width  = "120dp"  93   Android: layout_height  = "Wrap_content"      >          94      </  Button  >  95   </  Relativelayout  > 

1:

Figure 1: android_relativelayout instance