Android 怎么退出整个应用程序？

在开发andorid程序的时候，难免会牵扯到退出整个应用程序的情况，怎么完全退出呢？请参阅下面的关键代码：

[java] import java.util.LinkedList;
import java.util.List;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Application;
import android.content.DialogInte易做图ce;
import android.content.Intent;

public class SysApplication extends Application {
    private List<Activity> mList = new LinkedList<Activity>();
    private static SysApplication instance;

    private SysApplication() {
    }

    public synchronized static SysApplication getInstance() {
        if (null == instance) {
            instance = new SysApplication();
        }
        return instance;
    }

    // add Activity
    public void addActivity(Activity activity) {
        mList.add(activity);
    }

    public void exit() {
        try {
            for (Activity activity : mList) {
                if (activity != null)
                    activity.finish();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.exit(0);
        }
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        System.gc();
    }

}
import java.util.LinkedList;
import java.util.List;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Application;
import android.content.DialogInte易做图ce;
import android.content.Intent;

public class SysApplication extends Application {
private List<Activity> mList = new LinkedList<Activity>();
private static SysApplication instance;

private SysApplication() {
}

public synchronized static SysApplication getInstance() {
  if (null == instance) {
   instance = new SysApplication();
  }
  return instance;
}

// add Activity
public void addActivity(Activity activity) {
mList.add(activity);
}

public void exit() {
  try {
   for (Activity activity : mList) {
    if (activity != null)
     activity.finish();
   }
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   System.exit(0);
  }
}

@Override
public void onLowMemory() {
super.onLowMemory();
System.gc();
}

}在每个Activity的onCreate方法中添加类似代码：

[java] public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    SysApplication.getInstance().addActivity(this);
}
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  SysApplication.getInstance().addActivity(this);
}

在需要退出程序的时候，调用：

[java] SysApplication.getInstance().exit();
SysApplication.getInstance().exit();

简而言之，通过单例模式把每个Activity 的引用添加到一个全局链表中，每次退出程序调用System.exit(0)时，先调用链表中Activity 的finish方法

摘自心灵净土

补充：移动开发 , Android ,