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   android:layout_width="fill_parent"
 
  
  
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  It forces the view to expand to take up as much space as is available within the layout element it has been placed in.
  Setting a top-level layout to 
fill_parent will take up the whole screen. 
  For example, the top figure is the button width having fill_parent value and the middle one is the button height having fill_parent value.
  
   
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   android:layout_height="wrap_content"
  
 
 
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    Setting a view’s size to 
wrap_content will force it to expand only far enough to contain the values it contains.
    For example, the bottom figure is both button width and height having wrap_content value.
   
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   TextView class
  
 
 
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  This class displays text to the user.
 
 
 
   
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