浅析Android中的visibility属性

# public class MainActivity extends Activity { 
#     private TextView txt222 = null; 
#      
#     @Override 
#     protected void onCreate(Bundle savedInstanceState) { 
#         super.onCreate(savedInstanceState); 
#         setContentView(R.layout.main); 
#          
#         txt222 = (TextView)findViewById(R.id.txt2222); 
#          
#         findViewById(R.id.btn1).setOnClickListener(listener); 
#         findViewById(R.id.btn2).setOnClickListener(listener); 
#         findViewById(R.id.btn3).setOnClickListener(listener); 
#     } 
#      
#     View.OnClickListener listener = new View.OnClickListener() { 
#         @Override 
#         public void onClick(View v) { 
#             switch (v.getId()) { 
#             case R.id.btn1: 
#                 txt222.setVisibility(View.VISIBLE); 
#                 break; 
#  
#             case R.id.btn2: 
#                 txt222.setVisibility(View.INVISIBLE); 
#                 break; 
#                  
#             case R.id.btn3: 
#                 txt222.setVisibility(View.GONE); 
#                 break; 
#             } 
#         } 
#     }; 
# }

    <?xml version="1.0" encoding="utf-8"?> 
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
        android:layout_width="fill_parent" 
        android:layout_height="fill_parent" 
        android:orientation="vertical" > 

        <LinearLayout 
            android:layout_width="fill_parent" 
            android:layout_height="wrap_content" 
           android:layout_marginBottom="20dip" 
           android:orientation="horizontal" > 

           <TextView 
               android:layout_width="wrap_content" 
               android:layout_height="wrap_content" 
               android:layout_weight="1" 
               android:background="#F00" 
               android:text="1111" 
               android:visibility="visible" /> 

           <TextView 
               android:id="@+id/txt2222" 
               android:layout_width="wrap_content" 
               android:layout_height="wrap_content" 
               android:layout_weight="1" 
               android:background="#0F0" 
               android:text="2222" 
               android:visibility="visible" /> 
       </LinearLayout> 

       <Button 
           android:id="@+id/btn1" 
           android:layout_width="fill_parent" 
           android:layout_height="wrap_content" 
           android:text="2222 VISIBLE" /> 

       <Button 
           android:id="@+id/btn2" 
           android:layout_width="fill_parent" 
           android:layout_height="wrap_content" 
           android:text="2222 INVISIBLE" /> 

       <Button 
           android:id="@+id/btn3" 
           android:layout_width="fill_parent" 
           android:layout_height="wrap_content" 
           android:text="2222 GONE" /> 

   </LinearLayout>