The Long class includes a method named parseLong() that serves just this purpose. An example of a simple program that performs this conversion is shown below:

public class s2l {

   public static void main (String[] args) {

      // String s = "fred";    // do this if you want an exception

      String s = "100";

      try {
         long l = Long.parseLong(s.trim());
         System.out.println("long l = " + l);
      } catch (NumberFormatException nfe) {
         System.out.println("NumberFormatException: " + nfe.getMessage());
      }

   }

}

Other notes

• Long.toString(long l) is used to convert in the other direction, from long to String.
   
• If you're interested in converting a String to a Long object, use the valueOf() method of the Long class instead of the parseLong() method.

Related links

There is much more content related to Java and the String class on the blog, including these posts:

• A Java toString method that uses reflection to dynamically print class fields
• Use String.format to format a Java String
• A cheat sheet (reference page) for printf format specifiers


• How to convert a Java String to an int
• How to create an array of Strings (or any object) in Java
• A method to return the longest String in a given array of Strings