[Utils工具类整理]ActivityHelper

import java.util.ArrayList;import android.app.Activity;public class ActivityHelper {    private static ArrayList<Activity> mActivities = new ArrayList<Activity>();    public static void addActivity(Activity activity) {        if (!mActivities.contains(activity)) {            mActivities.add(activity);        }    }    public static void removeActivity(Activity activity) {        if (mActivities.contains(activity)) {            mActivities.remove(activity);        }    }    public static void closeAll() {        for (Activity activity : mActivities) {            if (activity != null && !activity.isFinishing()) {                activity.finish();            }        }    }}