我做了一个android studio项目，它可以正常工作，几天后，我想更改和更新我的应用程序，但是android studio将项目中的所有Java代码都显示为xml。

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2015 The Android Open Source Project
  ~
  ~ Licensed under the Apache License,Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~      http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing,software
  ~ distributed under the L