How to Add Width and Height to LayoutParams, in Java

public LinearLayout.LayoutParams (int width, int height) was added in API level 1
Parameters:
width - the width, either MATCH_PARENT, WRAP_CONTENT or a fixed size in pixels
height - the height, either MATCH_PARENT, WRAP_CONTENT or a fixed size in pixels

1. Declare a LayoutParams, in Java, named lp.

2. In the MainActivity.java, in the onCreate method, add the below line. This will set the LinearLayout.LayoutParams width to MATCH_PARENT and height to MATCH_PARENT.
** For API Level < 8, use fill_parent
** For API Level 8+, use match_parent (fill_parent is deprecated)

lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH.Parent);

3. Compile and run!

Resources:
http://developer.android.com/reference/android/view/ViewGroup.LayoutParams.html#MATCH_PARENT

android:layout_width - Set the Width of the TextView, in XML

How to Set the width of the TextView, in XML

android:layout_width was added in API Level 1
LayoutParams
Specifies the basic width of the TextView. This is a required attribute for any view inside of a containing layout manager.

1. Add a TextView in your main.xml file.

2. In the main.xml file, edit the code below. Using wrap_content the TextView will be only wide enough to enclose its content (plus padding).

  <TextView
        ...
       android:layout_width = "wrap_content"
  />

3. At this point, the code will work. But, to easier see the defines lines of the TextView, let's change the background color of the TextView to Gray. Hex: #808080

4. Compile and run!

5. Changing the android:width to match_parent will extend the width of the TextView to the end of its parent View (minus padding). (API 8 or greater)

6. If using API 7 or less, use fill_parent to yield the same results as match_parent.
This will fill as much horizontal space as it can, up to its parent. It should make the width as wide as it can be within the parent.

           android:layout_width = "fill_parent"

Related Articles:

Resources:
http://developer.android.com/reference/android/view/ViewGroup.LayoutParams.html#attr_android:layout_width
http://developer.android.com/reference/android/R.attr.html#layout_width