activity生命周期

<?xml version="1.0" encoding="utf-8"
    ?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="xieting"
        android:onClick="tiaozhuang"/>
</RelativeLayout>
java
package com.commerce.mylifeactivity;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        System.out.println("onCreate() xieting");
    }

    @Override
    protected void onResume() {
        super.onResume();
        System.out.println("onResume()xieting");
    }

    @Override
    protected void onStop() {
        super.onStop();
        System.out.println("onResume()xieting");
    }

    @Override
    protected void onPause() {
        super.onPause();
        System.out.println("onResume()xieting");
    }

    public void tiaozhuang(View view) {
        Intent intent=new Intent(MainActivity.this,MainActivity2.class);
        startActivity(intent);
        finish();

}

        @Override
        protected void onDestroy() {
            super.onDestroy();
            System.out.println("onResume()xieting");
        }

        @Override
        protected void onStart() {
            super.onStart();
            System.out.println("onResume()xieting");
        }
    }
xml2
<?xml version="1.0" encoding="utf-8"
    ?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity2">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="31"
        android:onClick="tiaozhuangdao"/>


</RelativeLayout>
java
package com.commerce.mylifeactivity;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;

public class MainActivity2 extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);


    }

    public void tiaozhuangdao(View view) {
        Intent intent=new Intent(MainActivity2.this,MainActivity.class);
        startActivity(intent);
    }
}