本文主要是介绍重新认识Android Activity的生命周期，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
http://peiquan.blog.51cto.com/7518552/1277373
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | public class ExampleActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); // The activity is being created. } @Override protected void onStart() { super .onStart(); // The activity is about to become visible. } @Override protected void onResume() { super .onResume(); // The activity has become visible (it is now "resumed"). } @Override protected void onPause() { super .onPause(); // Another activity is taking focus (this activity is about to be "paused"). } @Override protected void onStop() { super .onStop(); // The activity is no longer visible (it is now "stopped") } @Override protected void onDestroy() { super .onDestroy(); // The activity is about to be destroyed. } } |
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onSaveInstanceState()会在执行onStoped()方法之前调用，这个方法有一个参数Bundle，可以以“名称-值”的形式保存activity的信息（如使用putString(),putInt()方法）。接着在需要还原activity时，系统会调用onCreat()或者OnRestoreInstanceState()，这两个方法都传入一个以保存了activity信息的Bundle对象，通过提取Bundle对象的信息来恢复activity。如果没有信息需要保存到Bundle对象，那传递给这两个方法的将是空的Bundle对象（刚开始初始化一个activity时其实就是这种情况）。如下图所示：
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 | @Override protected void OnSaveInstanceState(Bundle outState) { outState.PutString( "myString" , "HelloXamarin.Android OnSaveInstanceState" ); outState.PutBoolean( "myBool" , true ); base.OnSaveInstanceState(outState); } @Override protected void OnRestoreInstanceState(Bundle savedState) { base.OnRestoreSaveInstanceState(savedState); var myString =savedState.GetString(amyStringa); var myBool =GetBoolean(amyBoola); } |
输出：
输出（注意其调用的顺序）：
输出：
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | public class ActivityA extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.activity_a); System.out.println( "ActivityA-->onCreate()" ); } @Override protected void onStart() { super .onStart(); System.out.println( "ActivityA-->onStart()" ); } @Override protected void onRestart() { super .onRestart(); System.out.println( "ActivityA-->onRestart()" ); } @Override protected void onResume() { super .onResume(); System.out.println( "ActivityA-->onResume()" ); } @Override protected void onPause() { super .onPause(); System.out.println( "ActivityA-->onPause()" ); } @Override protected void onStop() { super .onStop(); System.out.println( "ActivityA-->onStop()" ); } @Override protected void onDestroy() { super .onDestroy(); System.out.println( "ActivityA-->onDestroy()" ); } public void startDialog(View v) { Intent intent = new Intent(ActivityA. this , DialogActivity. class ); startActivity(intent); } public void startActivityB(View v) { Intent intent = new Intent(ActivityA. this , ActivityB. class ); startActivity(intent); } public void finishActivityA(View v) { ActivityA. this .finish(); } } Action |
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | public class DialogActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.activity_dialog); System.out.println( "DialogActivity-->onStart()" ); } @Override protected void onStart() { super .onStart(); System.out.println( "DialogActivity-->onStart()" ); } @Override protected void onRestart() { super .onRestart(); System.out.println( "DialogActivity-->onRestart()" ); } @Override protected void onResume() { super .onResume(); System.out.println( "DialogActivity-->onResume()" ); } @Override protected void onPause() { super .onPause(); System.out.println( "DialogActivity-->onPause()" ); } @Override protected void onStop() { super .onStop(); System.out.println( "DialogActivity-->onStop()" ); } @Override protected void onDestroy() { super .onDestroy(); System.out.println( "DialogActivity-->onDestroy()" ); } public void finishDialog(View v) { DialogActivity. this .finish(); } } |
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