Example: initials of a name

public class JFK {
  public static void main(String[] args) {
    String  first = "John";
    String  middle = "Fitzgerald";
    String  last = "Kennedy";
    String  initials;
    String  firstInit, middleInit, lastInit;
    firstInit = first.substring(0,1);
    middleInit = middle.substring(0,1);
    lastInit = last.substring(0,1);
    initials = firstInit.concat(middleInit);
    initials = initials.concat(lastInit);
    System.out.println(initials);
  }
}

// or simply
public class JFK2 {
  public static void main(String[] args) {
    String  first = "John";
    String  middle = "Fitzgerald";
    String  last = "Kennedy";
    System.out.println(first.substring(0,1).
                             concat(middle.substring(0,1)).
                             concat(last.substring(0,1)));
  }
}