Add escape "\" in front of special character for a string

There is actually a better way of doing this in a sleek manner.

String REGEX = "[\\[+\\]+:{}^~?\\\\/()><=\"!]";

StringUtils.replaceAll(inputString, REGEX, "\\\\$0");

Decide which special characters you want to escape and just call

query.replace("}", "\\}")

You may keep all special characters you allow in some array then iterate it and replace the occurrences as exemplified. This method replaces all regex meta characters.

public String escapeMetaCharacters(String inputString){
    final String[] metaCharacters = {"\\","^","$","{","}","[","]","(",")",".","*","+","?","|","<",">","-","&","%"};

    for (int i = 0 ; i < metaCharacters.length ; i++){
        if(inputString.contains(metaCharacters[i])){
            inputString = inputString.replace(metaCharacters[i],"\\"+metaCharacters[i]);
        }
    }
    return inputString;
}

You could use it as query=escapeMetaCharacters(query); Don't think that any library you would find would do anything more than that. At best it defines a complete list of specialCharacters.