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Replace HTML codes with equivalent characters in Java [duplicate]

Also, is there any way to optimize this regex? Yes, don’t use regex for this task, use Apache StringEscapeUtils from Apache commons lang: import org.apache.commons.lang.StringEscapeUtils; … String withCharacters = StringEscapeUtils.unescapeHtml(yourString); JavaDoc says: Unescapes a string containing entity escapes to a string containing the actual Unicode characters corresponding to the escapes. Supports HTML 4.0 entities. For … Read more

java regex pattern unclosed character class

Assuming that you want to match \ and – and not ]: Pattern pattern = Pattern.compile(“^[a-zA-Z\300-\3770-9\u0153\346 \u002F.’\\\\-]*$”); You need to double escape your backslashes, as \ is also an escape character in regex. Thus \\] escapes the backslash for java but not for regex. You need to add another java-escaped \ in order to regex-escape … Read more

Java Pattern Matcher: create new or reset?

By all means reuse the Matcher. The only good reason to create a new Matcher is to ensure thread-safety. That’s why you don’t make a public static Matcher m—in fact, that’s the reason a separate, thread-safe Pattern factory object exists in the first place. In every situation where you are sure there’s only one user … Read more

Convert Javascript regular expression to Java syntax

Change the leading and trailing “https://stackoverflow.com/” characters to ‘”‘, and then replace each ‘\’ with “\\”. Unlike, JavaScript, Perl and other scripting languages, Java doesn’t have a special syntax for regexes. Instead, they are (typically) expressed using Java string literals. But ‘\’ is the escape character in a Java string literal, so each ‘\’ in … Read more

What’s the difference between Mockito Matchers isA, any, eq, and same?

any() checks absolutely nothing. Since Mockito 2.0, any(T.class) shares isA semantics to mean “any T” or properly “any instance of type T“. This is a change compared to Mockito 1.x, where any(T.class) checked absolutely nothing but saved a cast prior to Java 8: “Any kind object, not necessary of the given class. The class argument … Read more

Java regex to match start/end tags causes stack overflow

Some more details on the origin of the stack overflow issue: Sometimes the regex Pattern class will throw a StackOverflowError. This is a manifestation of the known bug #5050507, which has been in the java.util.regex package since Java 1.4. The bug is here to stay because it has “won’t fix” status. This error occurs because … Read more

PatternSyntaxException: Illegal Repetition when using regex in Java

The { and } are special in Java’s regex dialect (and most other dialects for that matter): they are the opening and closing tokens for the repetition quantifier {n,m} where n and m are integers. Hence the error message: “Illegal repetition”. You should escape them: “\\{\”user_id\” : [0-9]*\\}”. And since you seem to be trying … Read more

How to extract parameters from a given url

It doesn’t have to be regex. Since I think there’s no standard method to handle this thing, I’m using something that I copied from somewhere (and perhaps modified a bit): public static Map<String, List<String>> getQueryParams(String url) { try { Map<String, List<String>> params = new HashMap<String, List<String>>(); String[] urlParts = url.split(“\\?”); if (urlParts.length > 1) { … Read more