（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。