一、点击返回键或者设备back键调用finish

private void back(){finish();
}或@Overridepublic void onBackPressed() {super.onBackPressed();}

二、结束进程

android.os.Process.killProcess(android.os.Process.myPid());

三、方法二exit结束java虚拟机

System.exit(0);

四、根据Activity的生命周期

            Intent intent = new Intent(context, QrcodePage.class);intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK |         Intent.FLAG_ACTIVITY_NEW_TASK);context.startActivity(intent);

五、常用的方法，使用Activity栈管理Activity

下面是工具类

/*** 界面管理*/public class ActivityUtil {private static final String TAG = "ActivityUtil";/*** 单一实例*/private static ActivityUtil sActivityUtil;/*** Activity堆栈 Stack:线程安全*/public Stack<Activity> mActivityStack = new Stack<>();/*** 私有构造器 无法外部创建*/private ActivityUtil() {}/*** 获取单一实例 双重锁定* @return this*/public static ActivityUtil getInstance() {if (sActivityUtil == null) {synchronized (ActivityUtil.class) {if (sActivityUtil == null) {sActivityUtil = new ActivityUtil();}}}return sActivityUtil;}/*** 添加Activity到堆栈*/public void addActivity(Activity activity) {mActivityStack.add(activity);}/*** 移除堆栈中的Activity* @param activity Activity*/public void removeActivity(Activity activity) {if (activity != null && mActivityStack.contains(activity)) {mActivityStack.remove(activity);}}/*** 获取当前Activity (堆栈中最后一个添加的)* @return Activity*/public Activity getCurrentActivity() {return mActivityStack.lastElement();}/*** 获取指定类名的Activity*/public Activity getActivity(Class<?> cls) {if (mActivityStack != null)for (Activity activity : mActivityStack) {if (activity.getClass().equals(cls)) {return activity;}}return null;}/*** 结束当前Activity (堆栈中最后一个添加的)*/public void finishCurrentActivity() {Activity activity = mActivityStack.lastElement();finishActivity(activity);}/*** 结束指定的Activity* @param activity Activity*/public void finishActivity(Activity activity) {if (activity != null && mActivityStack.contains(activity)) {mActivityStack.remove(activity);activity.finish();}}/*** 结束指定类名的Activity* @param clazz Activity.class*/public void finishActivity(Class<?> clazz) {for (Activity activity : mActivityStack) {if (activity.getClass().equals(clazz)) {finishActivity(activity);break;}}}/*** 结束所有Activity*/public void finishAllActivity() {for (int i = mActivityStack.size() - 1; i >= 0; i--) {if (mActivityStack.get(i) != null) {finishActivity(mActivityStack.get(i));}}mActivityStack.clear();}/*** 结束某个Activity之外的所有Activity*/public void finishAllActivityExcept(Class<?> clazz) {for (int i = mActivityStack.size() - 1; i >= 0; i--) {if (mActivityStack.get(i) != null && !mActivityStack.get(i).getClass().equals(clazz)) {finishActivity(mActivityStack.get(i));}}}/*** 退出应用程序*/public void exitApp() {try {finishAllActivity();} catch (Exception e) {e.printStackTrace();} finally {System.exit(0);}}/*** 判断某个Activity 界面是否在前台* @param context* @param className 某个界面名称* @return*/public static boolean  isForeground(Context context, String className) {if (context == null || TextUtils.isEmpty(className)) {return false;}ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);List<ActivityManager.RunningTaskInfo> list = am.getRunningTasks(1);if (list != null && list.size() > 0) {ComponentName cpn = list.get(0).topActivity;if (className.equals(cpn.getClassName())) {return true;}}return false;}}