一、匿名内部类

package com.example;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
//        通过id找到button（注意要强制类型转换）
        Button button = (Button) findViewById(R.id.button);
        
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
//                具体方法
                Toast.makeText(MainActivity.this,R.string.txt,Toast.LENGTH_SHORT).show();
            }
        });
    }
}

二、xml

xml中添加

android:onClick="clickme"

在Java中添加

public void clickme(View view)
{
    Toast.makeText(MainActivity.this,R.string.txt,Toast.LENGTH_LONG).show();
}

三、实现接口

package com.example;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId())
        {
            case R.id.button:
                Toast.makeText(MainActivity.this,R.string.txt,Toast.LENGTH_SHORT).show();
                break;
        }

    }
}