1. 创建项目

2. MainActivity.java

可以使用Android studio 自动生成代码

Code->Generate->Override Methods

选择(多选要按住Ctrl)

onCreate	
onResume	//获取焦点
onPause		//失去焦点
onRestart	//重启
onStart		//启动
onStop		//不可见时
onDestroy	//销毁

添加日志信息

package com.example.ex3;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.e("MainActivity","onCreate");
    }
    //获取焦点
    @Override
    protected void onResume() {
        super.onResume();
        Log.e("MainActivity","onResume");
    }
    //失去焦点
    @Override
    protected void onPause() {
        super.onPause();
        Log.e("MainActivity","onPause");
    }
    //重启
    @Override
    protected void onRestart() {
        super.onRestart();
        Log.e("MainActivity","onRestart");
    }
    //启动
    @Override
    protected void onStart() {
        super.onStart();
        Log.e("MainActivity","onStart");
    }
    //不可见时
    @Override
    protected void onStop() {
        super.onStop();
        Log.e("MainActivity","onStop");
    }
    //销毁
    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.e("MainActivity","onDestroy");
    }
}

设置日志过滤器

事件发生时会打印相应的日志