Android中Activity的生命周期

主界面A

package com.shellway.lifedemo

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import com.shellway.lifedemo.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {
    val tags = "MainActivity"
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        binding.button01.setOnClickListener {
             val intent = Intent(this,SecondActivity::class.java)
            startActivity(intent)
        }

        binding.button02.setOnClickListener {
            val intent = Intent(this,ThirdActivity::class.java)
            startActivity(intent)
        }
        Log.d(tags,"onCreate()...")
    }

    override fun onStart() {
        super.onStart()
        Log.d(tags,"onStart()...")
    }

    override fun onResume() {
        super.onResume()
        Log.d(tags,"onResume()...")
    }

    override fun onPause() {
        super.onPause()
        Log.d(tags,"onPause()...")
    }

    override fun onStop() {
        super.onStop()
        Log.d(tags,"onStop()...")
    }

    override fun onDestroy() {
        super.onDestroy()
        Log.d(tags,"onDestroy()...")
    }

    override fun onRestart() {
        super.onRestart()
        Log.d(tags,"onRestart()...")
    }
}

测试界面B

package com.shellway.lifedemo

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class SecondActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.second_activity)
    }
}

测试（对话框）界面C

package com.shellway.lifedemo

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class ThirdActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.third_activity)
    }
}

打印结果：

启动应用：onCreate()    onStart()   onResume()

A->B：onPause()    onStop()    

从B界面返回A：onRestart()   onStart()  onResume()

A-C:    onPause()

从C对话框返回A:   onResume()

退出应用：onPause()   onStop()   onDestroy()