标签：des android style blog http io ar color os
概述
和普通的Activity跳转稍微不同的是,当第1个Activity跳转到第二个Activity后,如果点击‘back‘按钮(即Android键盘的
按钮,则不会调用调用第一个Activity的onStop方法,因为弹出对话框的时候,第1个Activity对用户仍然是Visible(可见的).
如下,定义了两个继承Activity的java类:
1 package com.example.activitydialog; 2 3 import android.app.Activity; 4 import android.content.Intent; 5 import android.os.Bundle; 6 import android.view.Menu; 7 import android.view.View; 8 import android.view.View.OnClickListener; 9 import android.widget.Button; 10 11 public class MainActivity extends Activity { 12 13 private Button btn = null; 14 15 @Override 16 protected void onCreate(Bundle savedInstanceState) { 17 System.out.println("MainActivity onCreate"); 18 // TODO Auto-generated method stub 19 super.onCreate(savedInstanceState); 20 setContentView(R.layout.activity_main); 21 22 btn = (Button)findViewById(R.id.btnMain); 23 //pop a dialog activity. 24 btn.setOnClickListener(new OnClickListener() { 25 26 @Override 27 public void onClick(View v) { 28 Intent intent = new Intent(MainActivity.this, DialogActivity.class); 29 startActivity(intent); 30 } 31 }); 32 } 33 34 @Override 35 protected void onDestroy() { 36 System.out.println("MainActivity onDestroy"); 37 // TODO Auto-generated method stub 38 super.onDestroy(); 39 } 40 41 @Override 42 protected void onPause() { 43 System.out.println("MainActivity onPause"); 44 // TODO Auto-generated method stub 45 super.onPause(); 46 } 47 48 @Override 49 protected void onRestart() { 50 System.out.println("MainActivity onRestart"); 51 // TODO Auto-generated method stub 52 super.onRestart(); 53 } 54 55 @Override 56 protected void onResume() { 57 System.out.println("MainActivity onResume"); 58 // TODO Auto-generated method stub 59 super.onResume(); 60 } 61 62 @Override 63 protected void onStart() { 64 System.out.println("MainActivity onStart"); 65 // TODO Auto-generated method stub 66 super.onStart(); 67 } 68 69 @Override 70 protected void onStop() { 71 System.out.println("MainActivity onStop"); 72 // TODO Auto-generated method stub 73 super.onStop(); 74 } 75 76 77 @Override 78 public boolean onCreateOptionsMenu(Menu menu) { 79 // Inflate the menu; this adds items to the action bar if it is present. 80 getMenuInflater().inflate(R.menu.main, menu); 81 return true; 82 } 83 84 }
和
1 package com.example.activitydialog; 2 3 import android.app.Activity; 4 import android.content.Intent; 5 import android.os.Bundle; 6 import android.view.View; 7 import android.view.View.OnClickListener; 8 import android.widget.Button; 9 10 public class DialogActivity extends Activity { 11 12 private Button btn = null; 13 14 @Override 15 protected void onCreate(Bundle savedInstanceState) { 16 System.out.println("DialogActivity onCreate"); 17 // TODO Auto-generated method stub 18 super.onCreate(savedInstanceState); 19 setContentView(R.layout.activity_dialog); 20 21 btn = (Button) findViewById(R.id.btnDialog); 22 //go to the previous activity when click on the button. 23 btn.setOnClickListener(new OnClickListener() { 24 25 @Override 26 public void onClick(View v) { 27 Intent intent = new Intent(DialogActivity.this, MainActivity.class); 28 startActivity(intent); 29 } 30 }); 31 } 32 33 @Override 34 protected void onDestroy() { 35 System.out.println("DialogActivity onDestroy"); 36 // TODO Auto-generated method stub 37 super.onDestroy(); 38 } 39 40 @Override 41 protected void onPause() { 42 System.out.println("DialogActivity onPause"); 43 // TODO Auto-generated method stub 44 super.onPause(); 45 } 46 47 @Override 48 protected void onRestart() { 49 System.out.println("DialogActivity onRestart"); 50 // TODO Auto-generated method stub 51 super.onRestart(); 52 } 53 54 @Override 55 protected void onResume() { 56 System.out.println("DialogActivity onResume"); 57 // TODO Auto-generated method stub 58 super.onResume(); 59 } 60 61 @Override 62 protected void onStart() { 63 System.out.println("DialogActivity onStart"); 64 // TODO Auto-generated method stub 65 super.onStart(); 66 } 67 68 @Override 69 protected void onStop() { 70 System.out.println("DialogActivity onStop"); 71 // TODO Auto-generated method stub 72 super.onStop(); 73 } 74 75 }
并在layout中分别定义两个不同的布局xml文件:
(MainActivity对应的布局)
1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:paddingBottom="@dimen/activity_vertical_margin" 6 android:paddingLeft="@dimen/activity_horizontal_margin" 7 android:paddingRight="@dimen/activity_horizontal_margin" 8 android:paddingTop="@dimen/activity_vertical_margin" 9 tools:context=".MainActivity" > 10 11 <Button 12 android:id="@+id/btnMain" 13 android:layout_width="wrap_content" 14 android:layout_height="wrap_content" 15 android:text="@string/second_activity" /> 16 17 </RelativeLayout>
和
(DialogActivity对应的布局)
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" 6 > 7 <Button 8 android:id="@+id/btnDialog" 9 android:layout_width="fill_parent" 10 android:layout_height="fill_parent" 11 android:text="@string/second_activity" 12 /> 13 </LinearLayout>
当然,如果使用第二个Activity的按钮返回(而不是通过键盘的‘返回
‘的话,还是会调用第一个Activity的onStop方法).
这也充分说明了,官网对‘Activity生命周期的这3段话):
There are three key loops you may be interested in monitoring within your activity:
onCreate(Bundle) through to a single final call to onDestroy(). An activity will do all setup of "global" state in onCreate(), and release all remaining resources in onDestroy(). For example, if it has a thread running in the background to download data from the network, it may create that thread in onCreate() and then stop the thread in onDestroy().onStart() until a corresponding call to onStop(). During this time the user can see the activity on-screen, though it may not be in the foreground and interacting with the user. Between these two methods you can maintain resources that are needed to show the activity to the user. For example, you can register a BroadcastReceiver in onStart() to monitor for changes that impact your UI, and unregister it in onStop() when the user no longer sees what you are displaying. The onStart() and onStop() methods can be called multiple times, as the activity becomes visible and hidden to the user.onResume() until a corresponding call to onPause(). During this time the activity is in front of all other activities and interacting with the user. An activity can frequently go between the resumed and paused states -- for example when the device goes to sleep, when an activity result is delivered, when a new intent is delivered -- so the code in these methods should be fairly lightweight.Dialog式的Activity(AndroidActivity生命周期)
标签：des android style blog http io ar color os
原文地址：http://www.cnblogs.com/listened/p/4142646.html
