字符串处理错误
java.util.regex.PatternSyntaxException: Unclosed character class near index 0
原因
Exception in thread "main" java.util.regex.PatternSyntaxException: Unclosed character class near index 0 [ ^
出现此错误应该是字符转义出现问题：
System.out.println(str.replaceAll("[", "22"));
解决方案：在[之前加上\
System.out.println(str.replaceAll("\[", "22"));
