今天本來是想測試一個疑問,將1個子線程在activity A中建立。然後迅速的關閉掉activity A,我想知道這個子線程還會不會繼續跑。答案是會。這個子線程就好像跟activity A沒有關係似的,會一直跑完,直到結束。
相關代碼如下,首先是activity A:
package com.android.test;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class ActivityAndThredActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
MyThread mt = new MyThread();
mt.start();
Intent intent = new Intent(this, Next.class);
startActivity(intent);
finish();
}
}
package com.android.test;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class ActivityAndThredActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
MyThread mt = new MyThread();
mt.start();
Intent intent = new Intent(this, Next.class);
startActivity(intent);
finish();
}
}沒什麼特別的,啟動另外一個Activity之後,關閉自己
線程的代碼如下
/**
*
*/
package com.android.test;
import android.util.Log;
/**
* @author maqinghua
*
*/
public class MyThread extends Thread {
@Override
public void run() {
// TODO Auto-generated method stub
super.run();
try {
sleep(5000);
Inf.getInstance().info.add("Thread success");
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.d("test", "Thread error");
Inf.getInstance().info.add("Thread error");
}
Log.d("test", "Thread success");
}
}
其中用到了個Inf資訊類,用來記錄資訊和輸出的,如下:
/**
*
*/
package com.android.test;
import java.util.ArrayList;
/**
* @author maqinghua
*
*/
public class Inf {
private static Inf instance;
public ArrayList<String> info;
private Inf(){
info = new ArrayList<String>();
}
public static Inf getInstance(){
if(instance!=null){
return instance;
}else{
instance = new Inf();
return instance;
}
}
public String infToString(){
if(info!=null){
StringBuilder sb = new StringBuilder();
for(int i=0;i<info.size();i++){
sb.append(info.get(i));
}
return sb.toString();
}else{
return "";
}
}
}
最後是Next 類
/**
*
*/
package com.android.test;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.widget.TextView;
/**
* @author maqinghua
*
*/
public class Next extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.d("test", "onCreate()");
Inf.getInstance().info.add("onCreate()");
TextView tv = (TextView) findViewById(R.id.main);
String text = Inf.getInstance().infToString();
tv.setText(text);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
// TODO Auto-generated method stub
if(keyCode == KeyEvent.KEYCODE_BACK){
finish();
}
return super.onKeyDown(keyCode, event);
}
}
還有個布局檔案 main
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/main"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="20sp"
android:text="@string/hello" />
</LinearLayout>
測試的過程中,我發現個很有意思的事情。當我按返回鍵退出應用,然後在進應用。我驚奇的發現資訊類居然能夠記住上一次應用退出之前的資訊。 難道Inf資訊類不會隨著activity的消失而消亡嗎? 我又嘗試了幾次,發現真的不會。除非我們卸載掉應用,或者在程式管理中強制關閉它,它(Inf)才會被系統回收。
想給自己的應用做最佳化的同學們注意了,當你們要做退出處理的時候,記得刪除掉那些你想清除的static類,或者屬性。