Generate Random String in Apex

public static String generateRandomString() {
        final String chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz';
        String randStr = '';
        while (randStr.length() < 5) {
           Integer idx = Math.mod(Math.abs(Crypto.getRandomInteger()), chars.length());
           randStr += chars.substring(idx, idx+1);
        }
    system.debug('Value----'+randStr); 


    }