Java: convert String to Long and vice versa

// String to long
long l = Long.parseLong(str);

// long to string

String numCadena= String.valueOf(l);

Sources:
http://www.java-tips.org/java-se-tips/java.lang/conversion-from-string-to-long.html
http://www.java-examples.com/java-string-valueof-example