moveTaskToBack

• 场景：
  希望点击返回键时，当前页面不退出，而是app退到后台等

• class Activity function: public boolean moveTaskToBack(boolean nonRoot)

/**
     * Move the task containing this activity to the back of the activity
     * stack.  The activity's order within the task is unchanged.
     *
     * @param nonRoot If false then this only works if the activity is the root
     *                of a task; if true it will work for any activity in
     *                a task.
     *
     * @return If the task was moved (or it was already at the
     *         back) true is returned, else false.
     */
    public boolean moveTaskToBack(boolean nonRoot) {
        try {
            return ActivityManager.getService().moveActivityTaskToBack(
                    mToken, nonRoot);
        } catch (RemoteException e) {
            // Empty
        }
        return false;
    }