String s = e.nextLine();
String[] sa = s.split("+");
System.out.println(Arrays.toString(sa));
我的输入是“ 1 + 2 + 3”。正则表达式：“ +”给出悬挂的元字符错误。 是什么？
答案 0 :(得分：2)
正则表达式中的字符<body>
<!-- Video -->
<!-- XLG/LG - 21:9 aspect ratio -->
<div class="d-none d-lg-block embed-responsive embed-responsive-21by9 cab-video">
<video class="embed-responsive-item">
<source src="video.mp4">
</video>
</div>
<!-- MD - 16:9 aspect ratio -->
<div class="d-none d-md-block d-lg-none embed-responsive embed-responsive-16by9 cab-video">
<video class="embed-responsive-item">
<source src="video.mp4">
</video>
</div>
<!-- SM - 4:3 aspect ratio -->
<div class="d-none d-sm-block d-md-none embed-responsive embed-responsive-4by3 cab-video">
<video class="embed-responsive-item">
<source src="video.mp4">
</video>
</div>
<!-- XSM - 1:1 aspect ratio -->
<div class="d-block d-sm-none embed-responsive embed-responsive-1by1 cab-video">
<video class="embed-responsive-item">
<source src="video.mp4">
</video>
</div>
<!-- Video -->
<!-- Javascript files -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
</body>
是保留字符（表示“至少一个出现的先前写入的字符”）
要解决您的问题，您需要使用双反斜杠将其转义：+