Exception in thread "main" java.util.regex.PatternSyntaxException: Unclosed character class near index 3
[][]
^
at java.util.regex.Pattern.error(Pattern.java:1924)
at java.util.regex.Pattern.clazz(Pattern.java:2493)
at java.util.regex.Pattern.clazz(Pattern.java:2449)
at java.util.regex.Pattern.sequence(Pattern.java:2030)
at java.util.regex.Pattern.expr(Pattern.java:1964)
at java.util.regex.Pattern.compile(Pattern.java:1665)
at java.util.regex.Pattern.<init>(Pattern.java:1337)
at java.util.regex.Pattern.compile(Pattern.java:1022)
at java.lang.String.replaceAll(String.java:2162)
at Ideone.main(Main.java:13)