Android studio button Four ways to bind events [Instance code]

package com.geli_2.sujie.sujiegeili2testbutton;
import ;
import .;
import ;
import ;
import ;
public class MainActivity extends AppCompatActivity implements 
{
  private Button mBtClick;
  private Button mBtClick2;
  private Button mBtClick3;
  private Button mBtClick4;
  @Override
  protected void onCreate(Bundle savedInstanceState)
  {
    (savedInstanceState);
    setContentView(.activity_main);
    mBtClick = (Button) findViewById(.btnTest1);      //1, fdv find button id                                  // 2. Alt Ctrl F forms a global field    (new ()   //3. Type this line of code to automatically embed internal class method    {
      @Override
      public void onClick(View v)
      {                            //4. Toast tab tab call up toast method. The above is the method one        (, "hello world", Toast.LENGTH_SHORT).show();
      }
    });
    mBtClick2 = (Button) findViewById(.btnSample2);     //5. Find button id fdv of button 2    (new Button_2_OnClickListener()); //9. The instantiation method is bound to the button. The above is the method two    mBtClick3 = (Button) findViewById(.btnTry3);      //10. Find button id fdv of button 3    (this);             //11. This means main activity                                  //12 But here is the method parameter is the onclicklistener interface, and this Alt Enter will add the implemented interface to this method.    mBtClick4 = (Button) findViewById(.btnExample4);    //5. Find button id fdv of button 4  }
  /**
   * Called when a view has been clicked.
   *
   * @param v The view that was clicked.
   */
  @Override
  public void onClick(View v)
  {
    //Method 3  }
  class Button_2_OnClickListener implements  //6. Set a click method and inherit from view after naming it.                                  // onclicklistener
                                  //7. Then implement the method on inheriting implements alt + enter  {
    /**
     * Called when a view has been clicked.
     *
     * @param v The view that was clicked.
     */
    @Override
    public void onClick(View v)
    {
      //Method 2    }
  }
  public void click(View view)
  {
    //Method 4  }
}