Android studio button 按钮 四种绑定事件的方法

package com.geli_2.sujie.sujiegeili2testbutton;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener
{

    private Button mBtClick;
    private Button mBtClick2;
    private Button mBtClick3;
    private Button mBtClick4;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mBtClick = (Button) findViewById(R.id.btnTest1);            //1、fdv 找到button id
        // 2、 Alt Ctrl F 形成类全局Field
        mBtClick.setOnClickListener(new View.OnClickListener()      //3、键入此行代码自动嵌入内部类方法
        {
            @Override
            public void onClick(View v)
            {                                                       //4、 Toast tab tab 调出toast 方法 以上为方法一
                Toast.makeText(MainActivity.this, "hello world1", Toast.LENGTH_SHORT).show();
            }
        });


        mBtClick2 = (Button) findViewById(R.id.btnSample2);         //5、找出button 2 的 button id   fdv
        mBtClick2.setOnClickListener(new Button_2_OnClickListener()); //9、实例化方法给button 绑定  以上是方法二
        mBtClick3 = (Button) findViewById(R.id.btnTry3);            //10、找出button 3 的 button id   fdv
        mBtClick3.setOnClickListener(this);                         //11、 this 表示 main acitivity
        //12 但是这里是方法参数是onclicklistener接口，此处 this Alt Enter 会在此方法上加上实现的接口以上是方法三
        mBtClick4 = (Button) findViewById(R.id.btnExample4);        //5、找出button 4 的 button id   fdv  方法四这行没用


    }

    /**
     * Called when a view has been clicked.
     *
     * @param v The view that was clicked.
     */
    @Override
    public void onClick(View v)
    {
        Toast.makeText(MainActivity.this, "hello world 3", Toast.LENGTH_SHORT).show();//方法三
    }

    class Button_2_OnClickListener implements View.OnClickListener  //6、设置一个 click 方法  命名后继承自 view
            // onclicklistener
            //7、 后在 继承 implements 上 alt + enter 来实现方法
    {

        /**
         * Called when a view has been clicked.
         *
         * @param v The view that was clicked.
         */
        @Override
        public void onClick(View v)
        {
            Toast.makeText(MainActivity.this, "hello world 2", Toast.LENGTH_SHORT).show();//方法二
        }
    }
    public void click(View view)
    {
        Toast.makeText(MainActivity.this, "hello world 4", Toast.LENGTH_SHORT).show();//方法四
    }

}