（Android）Activity生命周期详解（原创）

1.先来张官方文档的生命周期图

 

2.下面我们用代码解释Activity生命周期

FirstActivity.java

package mars.activity04;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class FirstActivity extends Activity implements OnClickListener{
    private Button btn1;
    private Button btn2;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.first);
        btn1 = (Button)findViewById(R.id.Btn1);
        btn2 = (Button)findViewById(R.id.Btn2);
        btn1.setOnClickListener(this);
        btn2.setOnClickListener(this);
        System.out.println("FirstAcvity-------------------------->onCreate");
    }
    @Override
    protected void onStart() {
        // TODO Auto-generated method stub
        super.onStart();
        System.out.println("FirstAcvity-------------------------->onStart");
    }
    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        System.out.println("FirstAcvity-------------------------->onResume");
    }
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        System.out.println("FirstAcvity-------------------------->onPause");
    }
    @Override
    protected void onStop() {
        // TODO Auto-generated method stub
        super.onStop();
        System.out.println("FirstAcvity-------------------------->onStop");
    }
    @Override
    protected void onRestart() {
        // TODO Auto-generated method stub
        super.onRestart();
        System.out.println("FirstAcvity-------------------------->onRestart");
    }
    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        System.out.println("FirstAcvity-------------------------->onDestroy");
    }
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch(v.getId()){
        case R.id.Btn1:
            Intent intent = new Intent();
            intent.setClass(this,SecondActivity.class);
            startActivity(intent);
            break;
        case R.id.Btn2:
            this.finish();
            System.out.println("FirstAcvityfinish-------------------------->");
            break;
        }
    }
}

SecondActivity.java

public class SecondActivity extends Activity implements OnClickListener {
    private Button btn1;
    private Button btn2;
    private Button btn3;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);
        btn1 = (Button)findViewById(R.id.backbtn);
        btn2 = (Button)findViewById(R.id.thirdButton);
        btn3 = (Button)findViewById(R.id.finish2);
        btn1.setOnClickListener(this);
        btn2.setOnClickListener(this);
        btn3.setOnClickListener(this);
        System.out.println("SecondActivity-------------------------->onCreate");
        
    }
    @Override
    protected void onStart() {
        // TODO Auto-generated method stub
        super.onStart();
        System.out.println("SecondAcvity-------------------------->onStart");
    }
    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        System.out.println("SecondAcvity-------------------------->onResume");
    }
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        System.out.println("SecondAcvity-------------------------->onPause");
    }
    @Override
    protected void onStop() {
        // TODO Auto-generated method stub
        super.onStop();
        System.out.println("SecondAcvity-------------------------->onStop");
    }
    @Override
    protected void onRestart() {
        // TODO Auto-generated method stub
        super.onRestart();
        System.out.println("SecondAcvity-------------------------->onRestart");
    }
    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        System.out.println("SecondAcvity-------------------------->onDestroy");
    }
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch(v.getId()){
        case R.id.backbtn:
            Intent intent1 = new Intent();
            intent1.setClass(this,FirstActivity.class);
            startActivity(intent1);
            break;
        case R.id.thirdButton:
            Intent intent2 = new Intent();
            intent2.setClass(this,ThirdActivity.class);
            startActivity(intent2);
            break;
        case R.id.finish2:
            this.finish();
            System.out.println("SecondAcvityfinish-------------------------->");
            break;
        }
    }
}

ThirdActivity.java

public class ThirdActivity extends Activity implements OnClickListener{
    private Button btn;
    private Button btn2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.third);
        btn=(Button)findViewById(R.id.backToSecondButton);
        btn2=(Button)findViewById(R.id.finish3);
        btn.setOnClickListener(this);
        btn2.setOnClickListener(this);
        System.out.println("ThirdAcvity-------------------------->onCreate");
    }
    @Override
    protected void onStart() {
        // TODO Auto-generated method stub
        super.onStart();
        System.out.println("ThirdAcvity-------------------------->onStart");
    }
    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        System.out.println("ThirdAcvity-------------------------->onResume");
    }
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        System.out.println("ThirdAcvity-------------------------->onPause");
    }
    @Override
    protected void onStop() {
        // TODO Auto-generated method stub
        super.onStop();
        System.out.println("ThirdAcvity-------------------------->onStop");
    }
    @Override
    protected void onRestart() {
        // TODO Auto-generated method stub
        super.onRestart();
        System.out.println("ThirdAcvity-------------------------->onRestart");
    }
    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        System.out.println("ThirdAcvity-------------------------->onDestroy");
    }
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch(v.getId()){
        case R.id.backToSecondButton:
            Intent intent=new Intent();
            intent.setClass(this, SecondActivity.class);
            startActivity(intent);
            break;
        case R.id.finish3:
            this.finish();
            System.out.println("ThirdAcvityfinish-------------------------->");
            break;
        }
    }

运行结果：

 

 

启动程序FirstAcvity：
FirstAcvity-------------------------->onCreate

FirstAcvity-------------------------->onStart
FirstAcvity-------------------------->onResume

启动SecondAcvity：（注意onPause和onStop是分开的）
FirstAcvity-------------------------->onPause
SecondActivity----------------------->onCreate

SecondAcvity------------------------->onStart

SecondAcvity------------------------->onResume

FirstAcvity-------------------------->onStop

启动ThirdAcvity：（ThirdAcvity是Dialog类型的Activity）
SecondAcvity------------------------->onPause

ThirdAcvity-------------------------->onCreate
ThirdAcvity-------------------------->onStart

ThirdAcvity-------------------------->onResume

返回SecondAcvity：（Intent就是Create Activity）
ThirdAcvity-------------------------->onPause
SecondAcvity------------------------->onStop

SecondActivity----------------------->onCreate

SecondAcvity------------------------->onStart
SecondAcvity------------------------->onResume

ThirdAcvity-------------------------->onStop

返回FirstAcvity：
SecondAcvity-------------------------->onPause

FirstAcvity--------------------------->onCreate

FirstAcvity--------------------------->onStart

FirstAcvity--------------------------->onResume

SecondAcvity-------------------------->onStop

FirstAcvity下按home键：(正常的变得不可见)
FirstAcvity--------------------------->onPause
FirstAcvity--------------------------->onStop

重新回到FirstAcvity:(正常的操控Activity)
FirstAcvity--------------------------->onRestart
FirstAcvity--------------------------->onStart
FirstAcvity--------------------------->onResume

ThirdAcvity下按home键：
ThirdAcvity-------------------------->onPause
SecondAcvity-------------------------->onStop
ThirdAcvity-------------------------->onStop

重新回到ThirdAcvity
SecondAcvity-------------------------->onRestart

SecondAcvity-------------------------->onStart

ThirdAcvity-------------------------->onRestart

ThirdAcvity-------------------------->onStart
ThirdAcvity-------------------------->onResume

FirstAcvity下熄屏：（相当于锁屏来到前端Another Activity，相当于FirstAcvity还可见）
FirstAcvity-------------------------->onPause
亮屏解锁到FirstAcvity：（返回）
FirstAcvity-------------------------->onResume

FirstAcvity下另一个app的Activity来到前端：(正常的变得不可见)

FirstAcvity-------------------------->onPause
FirstAcvity-------------------------->onStop

回到FirstAcvity:(正常的操控Activity)
FirstAcvity-------------------------->onRestart

FirstAcvity-------------------------->onStart
FirstAcvity-------------------------->onResume

FirstAcvity中调用finish()：

FirstAcvityfinish-------------------------->
FirstAcvity-------------------------->onPause

FirstAcvity-------------------------->onStop

FirstAcvity-------------------------->onDestroy

SecondAcvity中调用finish()：
SecondAcvityfinish-------------------------->

SecondAcvity-------------------------->onPause
FirstAcvity-------------------------->onRestart
FirstAcvity-------------------------->onStart

FirstAcvity-------------------------->onResume

SecondAcvity-------------------------->onStop

SecondAcvity-------------------------->onDestroy

ThirdAcvity中调用finish()：
ThirdAcvityfinish-------------------------->
ThirdAcvity-------------------------->onPause

SecondAcvity-------------------------->onResume

ThirdAcvity-------------------------->onStop

ThirdAcvity-------------------------->onDestroy

 关闭程序后重新启动FirstActivity：

...

启动SecondActivity：

...

启动ThirdActivity：

...

按Back键，返回SecondActivity：

ThirdAcvity-------------------------->onPause
SecondAcvity-------------------------->onResume
ThirdAcvity-------------------------->onStop
ThirdAcvity-------------------------->onDestroy

按Back键，返回FirstActivity：

SecondAcvity-------------------------->onPause
FirstAcvity-------------------------->onRestart
FirstAcvity-------------------------->onStart
FirstAcvity-------------------------->onResume
SecondAcvity-------------------------->onStop
SecondAcvity-------------------------->onDestroy

按Back键，返回桌面：

 FirstAcvity-------------------------->onPause
FirstAcvity-------------------------->onStop
FirstAcvity-------------------------->onDestroy

 

finish说明:对于finish，调用finish后，不会立即调用onDestroy，

而是在执行完finish后的代码后调用onPause，onStop，onDestroy；

 4.Activity栈：

ps：调用后create，所属Activity会进栈；调用了onDestroy，所属Activity会出栈；前端Activity总是在栈顶

使用以下操作：

 启动1启动SecondActivity     ->     2返回一个Activity     ->     1finish->     2finish      ->     1finish

 

栈情况：

运行结果：

1.启动 FirstAcvity：

 FirstAcvity-------------------------->onCreate
FirstAcvity-------------------------->onStart 

FirstAcvity-------------------------->onResume

2.启动 SecondActivity：
FirstAcvity-------------------------->onPause
 SecondActivity-------------------------->onCreate
 SecondAcvity-------------------------->onStart
 SecondAcvity-------------------------->onResume
 FirstAcvity-------------------------->onStop

3.返回第一个Activity：
 SecondAcvity-------------------------->onPause
 FirstAcvity-------------------------->onCreate
 FirstAcvity-------------------------->onStart
 FirstAcvity-------------------------->onResume
SecondAcvity-------------------------->onStop

 4.

 FirstAcvityfinish-------------------------->
 FirstAcvity-------------------------->onPause
 SecondAcvity-------------------------->onRestart
 SecondAcvity-------------------------->onStart
 SecondAcvity-------------------------->onResume
FirstAcvity-------------------------->onStop
FirstAcvity-------------------------->onDestroy

5.
 SecondAcvityfinish-------------------------->
 SecondAcvity-------------------------->onPause
FirstAcvity-------------------------->onRestart
 FirstAcvity-------------------------->onStart
 FirstAcvity-------------------------->onResume
 SecondAcvity-------------------------->onStop
 SecondAcvity-------------------------->onDestroy

6.
 FirstAcvityfinish-------------------------->
 FirstAcvity-------------------------->onPause
FirstAcvity-------------------------->onStop
 FirstAcvity-------------------------->onDestroy

 

由以上知，转到某一个Activity，必然会调用onResume方法，故这个Activity的一些初始化工作一般放到onResume里面。

 

现在Activity生命周期应该理解得差不多了，如有错误，欢迎指正。