Examples of using button buttons in Android development and dynamically adding components

package .lab2;
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public class MainActivity extends Activity {
  EditText et1;       //Enter the EditText of the username  EditText et2;      //EditText for entering password  ImageButton ib;      //Declare ImageButton  Button btn;        //Reset button  Context context;
  LinearLayout mLinearLayout;      //This LineatLayout is used to place added components  TextView tv;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    (savedInstanceState);
    setContentView(.activity_main);
    init(); //initialization    //Click imagebutton    OnClickListener listener = new OnClickListener() {
      @Override
      public void onClick(View arg0) {
        // TODO Auto-generated method stub
        if(().toString().equals("android") && ().toString().equals("2015"))
        {
          (.state1);  //Setting to change the original picture          ();
          ();
        }
        else   //When entering the account or password incorrectly        {
          ("");
          ("Error account or password");
        }
      }
    };
    (listener);
    //Long press imagebutton    OnLongClickListener longlistener = new OnLongClickListener() {
      @Override
      public boolean onLongClick(View arg0) {
        // TODO Auto-generated method stub
        (context, "The TextView has been added dynamically", Toast.LENGTH_SHORT);
        tv = new TextView(context);
        ("Here is a dynamically added TextView");
        (tv);      //Add components        return false;
      }
    };
    (longlistener);
    //Reset    OnClickListener listener2 = new OnClickListener() {
      @Override
      public void onClick(View arg0) {
        // TODO Auto-generated method stub
        (.state2);
        ("Please enter a username");
        ("Please enter your password");
        ("");
        ("");
        (); //Position the cursor EditText        ();
        ();
        ();    //When clicking the reset button, the original added components will be cleared together      }
    };
    (listener2);
  }
  //Initialize the function  public void init()
  {
    et1 = (EditText)findViewById(.et_username);
    et2 = (EditText)findViewById(.et_passward);
    ib = (ImageButton)findViewById();
    btn = (Button)findViewById();
    context = ;
    mLinearLayout = (LinearLayout)findViewById();
  }
}

<LinearLayout xmlns:andro
  xmlns:tools="/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"
 >
  <EditText
    android:
    android:hint="Please enter a username"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
   <EditText
    android:
    android:hint="Please enter your password"
    android:inputType="textPassword"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>
   <ImageButton
     android:
     android:src="@drawable/state2"
     android:layout_width="50dp"
     android:layout_height="50dp"/>
   <Button
     android:
     android:text="Reset"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"/>
   <LinearLayout
     android:
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:orientation="vertical">
   </LinearLayout>
</LinearLayout>