Android 关于Activity生命周期

先看一张图

下面会用程序进行演示：

package com.example.myapplication;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.view.KeyEventDispatcher;

import android.content.ComponentName;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {    //继承

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);               //父类之中调用
         setContentView(R.layout.activity_main);//R(资源调用的一个类)选择了一个界面显示了出来
       /* Log.i("MainActivityMSG","iiMessage");
        Log.d("MainActivityMSG","diMessage");
        Log.e("MainActivityMSG","eiMessage");
        Log.w("MainActivityMSG","wiMessage"); //可以进行日志的输出，是调试的重要手段,会在日志中打印出后面这句话

    */
        Log.e("activityState","MainActivity_onCreate");
    }

    protected void onStart(){
        super.onStart();
        Log.e("activityState","MainActivity_onStart");
    }
    protected void onRestart(){
        super.onRestart();
        Log.e("activityState","MainActivity_onRestart");
    }
    protected void onResume() {
        super.onResume();
        Log.e("activityState", "MainActivity_onResume");
    }
    protected void onPause(){
        super.onPause();
        Log.e("activityState","MainActivity_onPause");
    }
    protected void onStop(){
        super.onStop();
        Log.e("activityState","MainActivity_onStop");
    }
    protected void onDestroy(){
        super.onDestroy();
        Log.e("activityState","MainActivity_onDestroy");
    }




    public void sendMessage(View view){
        //相应按钮的事件
        EditText msg=findViewById(R.id.message);
        String s=msg.getText().toString();
        Log.e("sendMessage",s);
      //写法一  Intent intent =new Intent(this ,SecondActivity.class);
        // this.startActivity(intent);
        //写法二
        //Intent   intent=new Intent();
        //intent.setClassName(this,"com.example.myapplication.SecondActivity");
        //startActivity(intent);
        //写法三
        //Intent intent =new Intent();
        //ComponentName cname=new ComponentName(this ,SecondActivity.class);
        //intent.setComponent(cname);
        //startActivity(intent);
        //写法四 隐式启动
 //       Intent intent=new Intent("android.intent.action.nextActivity");
 //       startActivity(intent);
    }
}

下面进行第一次启动：可以看到启动后如下日志

020-12-04 09:30:46.185 28359-28359/com.example.myapplication E/activityState: MainActivity_onCreate
2020-12-04 09:30:46.189 28359-28359/com.example.myapplication E/activityState: MainActivity_onStart
2020-12-04 09:30:46.195 28359-28359/com.example.myapplication E/activityState: MainActivity_onResume
2020-12-04 09:30:46.320 28359-28391/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008cdf
2020-12-04 09:30:46.320 28359-28391/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008cdf
2020-12-04 09:30:46.320 28359-28391/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008824
2020-12-04 09:30:46.320 28359-28391/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008824
2020-12-04 09:31:11.620 28359-28359/com.example.myapplication E/activityState: MainActivity_onPause
2020-12-04 09:31:11.686 28359-28359/com.example.myapplication E/activityState: MainActivity_onStop
2020-12-04 09:32:31.253 28359-28359/com.example.myapplication E/activityState: MainActivity_onRestart
2020-12-04 09:32:31.272 28359-28359/com.example.myapplication E/activityState: MainActivity_onStart
2020-12-04 09:32:31.329 28359-28359/com.example.myapplication E/activityState: MainActivity_onResume
2020-12-04 09:32:33.593 28359-28359/com.example.myapplication E/activityState: MainActivity_onPause
2020-12-04 09:32:33.763 28359-28359/com.example.myapplication E/activityState: MainActivity_onStop

可以验证到上面的流程图是正确的。最后再来一张总结图

后面做了一下类似的实验，只不过这次有两个Activity主要观察他的跳转的时候的关系。这里就不记录具体的做法了。下面是打印出的日志。

2020-12-04 10:14:13.636 10218-10218/com.example.myapplication E/activityState: MainActivity_onCreate
2020-12-04 10:14:13.643 10218-10218/com.example.myapplication E/activityState: MainActivity_onStart
2020-12-04 10:14:13.656 10218-10218/com.example.myapplication E/activityState: MainActivity_onResume
2020-12-04 10:14:13.874 10218-10273/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008cdf
2020-12-04 10:14:13.876 10218-10273/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008cdf
2020-12-04 10:14:13.876 10218-10273/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008824
2020-12-04 10:14:13.877 10218-10273/com.example.myapplication E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008824
2020-12-04 10:14:54.683 10218-10218/com.example.myapplication E/activityState: MainActivity_onPause
2020-12-04 10:14:54.733 10218-10218/com.example.myapplication E/activityState: MainActivity_onStop
2020-12-04 10:14:58.273 10218-10218/com.example.myapplication E/activityState: MainActivity_onRestart
2020-12-04 10:14:58.286 10218-10218/com.example.myapplication E/activityState: MainActivity_onStart
2020-12-04 10:14:58.329 10218-10218/com.example.myapplication E/activityState: MainActivity_onResume
2020-12-04 10:15:03.808 10218-10218/com.example.myapplication E/activityState: MainActivity_onPause
2020-12-04 10:15:04.085 10218-10218/com.example.myapplication E/activityState: SecondActivity_onCreate
2020-12-04 10:15:04.087 10218-10218/com.example.myapplication E/activityState: SecondActivity_onStart
2020-12-04 10:15:04.091 10218-10218/com.example.myapplication E/activityState: SecondActivity_onResume
2020-12-04 10:15:04.805 10218-10218/com.example.myapplication E/activityState: MainActivity_onStop
2020-12-04 10:15:08.508 10218-10218/com.example.myapplication E/activityState: SecondActivity_finish关闭按钮点击时打出的log
2020-12-04 10:15:08.529 10218-10218/com.example.myapplication E/activityState: SecondActivity_onPause
2020-12-04 10:15:08.576 10218-10218/com.example.myapplication E/activityState: MainActivity_onRestart
2020-12-04 10:15:08.577 10218-10218/com.example.myapplication E/activityState: MainActivity_onStart
2020-12-04 10:15:08.578 10218-10218/com.example.myapplication E/activityState: MainActivity_onResume
2020-12-04 10:15:09.144 10218-10218/com.example.myapplication E/activityState: SecondActivity_onStop
2020-12-04 10:15:09.148 10218-10218/com.example.myapplication E/activityState: SecondActivity_onDestroy
2020-12-04 10:16:08.492 10218-10218/com.example.myapplication E/activityState: MainActivity_onPause
2020-12-04 10:16:08.532 10218-10218/com.example.myapplication E/activityState: MainActivity_onStop

本文地址：https://blog.csdn.net/a15929748502/article/details/110559090

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