作为Android的四个组件之一,Activity在实际开发中起着重要的作用。 了解声明周期有助于今后的开发。 让我们来看看Activity在各种情况下的生命周期
准备两个Activity、IndexActivity和TwoActivity
publicclassindexactivityextendsappcompatactivity {
publicstaticfinalstringtag=' index activity ';
@Override
保护性视频创建(bundlesavedinstancestate )。
super.oncreate (savedinstancestate;
setcontentview (r.layout.activity _ main;
findviewbyid (r.id.text _ request _ one ).setonclicklistener ) newview.onclicklistener
@Override
公共void onclick (viewv ) {
开始活动(new intent (index activity.this,TwoActivity.class ) );
}
);
log.I(tag,' onCreate ' );
}
@Override
受保护的语音开始
super.onStart (;
log.I(tag,' onStart ' );
}
@Override
受保护的void on restart
super.onRestart (;
log.I(tag,' onRestart ' );
}
@Override
受保护的void on resume
super.onResume (;
log.I(tag,' onResume ' );
}
@Override
受保护的void on pause
super.onPause (;
log.I(tag,' onPause ' );
}
@Override
受保护的语音停止
super.onStop (;
log.I(tag,' onStop ' );
}
@Override
受保护的void on destroy
super.onDestroy (;
log.I(tag,' onDestroy ' );
}
@Override
protectedvoidonnewintent (intent intent ) (
super.onnewintent(intent );
log.I(tag,' onNewIntent ' );
}
}
publicclasstwoactivityextendsappcompatactivity {
publicstaticfinalstringtag=' two activity ';
@Override
保护性视频创建(bundlesavedinstancestate )。
super.oncreate (savedinstancestate;
setcontentview (r.layout.activity _ main;
log.I(tag,' onCreate ' );
}
@Override
受保护的语音开始
super.onStart (;
log.I(tag,' onStart ' );
}
@Override
受保护的void on restart
super.onRestart (;
log.I(tag,' onRestart ' );
}
@Override
受保护的void on resume
super.onResume (;
log.I(tag,' onResume ' );
}
@Override
受保护的void on pause
super.onPause (;
Log.i(TAG, "onPause");
}
@Override
protected void onStop() {
super.onStop();
Log.i(TAG, "onStop");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.i(TAG, "onDestroy");
}
}
启动App IndexActivity的生命周期
01-22 15:44:02.131 23541-23541/fe.dotwoven I/IndexActivity: onCreate
01-22 15:44:02.131 23541-23541/fe.dotwoven I/IndexActivity: onStart
01-22 15:44:02.133 23541-23541/fe.dotwoven I/IndexActivity: onResume
启动IndexActivity分别调用了onCreate,onStart, onResume方法。
按Home键回到桌面 Activity生命周期
01-22 15:46:52.583 23541-23541/fe.dotwoven I/IndexActivity: onPause
01-22 15:46:53.110 23541-23541/fe.dotwoven I/IndexActivity: onStop
回到桌面会调用IndexActivity的onPause,onStop方法
从桌面再次进入IndexActivity 生命周期
01-22 15:47:51.388 23541-23541/fe.dotwoven I/IndexActivity: onRestart
01-22 15:47:51.388 23541-23541/fe.dotwoven I/IndexActivity: onStart
01-22 15:47:51.388 23541-23541/fe.dotwoven I/IndexActivity: onResume
再次进入的时候调用了IndexActivity的onRestart,onStart,onResume方法
IndexActivity上按返回键时生命周期
01-22 15:50:03.004 23541-23541/fe.dotwoven I/IndexActivity: onPause
01-22 15:50:03.558 23541-23541/fe.dotwoven I/IndexActivity: onStop
01-22 15:50:03.558 23541-23541/fe.dotwoven I/IndexActivity: onDestroy
分别执行了IndexActivity的onPause,onStop,onDestroy方法
从IndexActivity跳转到TwoActivity生命周期
01-22 15:51:54.183 23541-23541/fe.dotwoven I/IndexActivity: onPause
01-22 15:51:54.270 23541-23541/fe.dotwoven I/TwoActivity: onCreate
01-22 15:51:54.271 23541-23541/fe.dotwoven I/TwoActivity: onStart
01-22 15:51:54.273 23541-23541/fe.dotwoven I/TwoActivity: onResume
01-22 15:51:54.688 23541-23541/fe.dotwoven I/IndexActivity: onStop
首先会执行IndexActivity的onPause方法,接下来执行TwoActivity的onCreate,onStart,onResume方法;最后才会执行IndexActivity的onStop方法,最后这点大家要记住
TwoActivity按返回键返回IndexActivity生命周期
01-22 15:53:49.444 23541-23541/fe.dotwoven I/TwoActivity: onPause
01-22 15:53:49.484 23541-23541/fe.dotwoven I/IndexActivity: onRestart
01-22 15:53:49.485 23541-23541/fe.dotwoven I/IndexActivity: onStart
01-22 15:53:49.494 23541-23541/fe.dotwoven I/IndexActivity: onResume
01-22 15:53:49.870 23541-23541/fe.dotwoven I/TwoActivity: onStop
01-22 15:53:49.870 23541-23541/fe.dotwoven I/TwoActivity: onDestroy
首先会执行TwoActivity的onPause方法,接下来调用IndexActivity的onRestart,onStart,onResume方法,最后再调用TwoActivity的onStop和onDestroy方法。
启动模式不同 Activity的生命周期
如果IndexActivity的启动模式是singleTask或是singleInstance,然后从IndexActivity跳转到TwoActivity,再从TwoActivity跳转到IndexActivity,这个时候生命周期会有什么不同呢?我们来看看
01-22 16:07:53.739 18403-18403/fe.dotwoven I/TwoActivity: onPause
01-22 16:07:53.762 18403-18403/fe.dotwoven I/IndexActivity: onNewIntent
01-22 16:07:53.762 18403-18403/fe.dotwoven I/IndexActivity: onRestart
01-22 16:07:53.765 18403-18403/fe.dotwoven I/IndexActivity: onStart
01-22 16:07:53.767 18403-18403/fe.dotwoven I/IndexActivity: onResume
01-22 16:07:54.103 18403-18403/fe.dotwoven I/TwoActivity: onStop
01-22 16:07:54.103 18403-18403/fe.dotwoven I/TwoActivity: onDestroy
IndexActivity多调用了一个onNewIntent方法。
如果IndexActivity的启动模式是singleTop,然后从IndexActivity启动到IndexActivity,它其实显示的还是IndexActivity,那IndexActivity的生命周期会有什么不同呢?
01-22 16:13:03.392 4830-4830/fe.dotwoven I/IndexActivity: onPause
01-22 16:13:03.392 4830-4830/fe.dotwoven I/IndexActivity: onNewIntent
01-22 16:13:03.393 4830-4830/fe.dotwoven I/IndexActivity: onResume
可以看到它先调用了自己的onPause方法,然后调用了onNewIntent,onResume方法。
总结
到此Activity各个场景的生命周期差不多都分析完了,理解好Activity的生命周期有利于我们的开发工作