Find if the String is a number or floating point number - Regular Expression
Find if a string contains only digits? public static boolean stringContainsOnlyDigits(String s) { Pattern p = Pattern.compile( "^[0-9]+$" ); Matcher m = p.matcher( s ); return m.find(); } Find if the String is a Floating Point number. public static boolean stringIsFloatingPointNumber(String s) { Pattern p = Pattern.compile( "^[-+]?[0-9]*\\.?[0-9]+$" ); Matcher m = p.matcher( s ); boolean found = m.find(); if(found) { System.out.println("found: " + m.group(0)); } return found; } The caveat here is the strings are long text and Double.parseDouble() will be out of range. Such problems can be solved only using Regular Expressions .