public class Foo {

  String _a;
  Integer _b;

  public String a() {

     if (_a == null)   _a = retrieveA();
     return _a;
  }

  public Integer b() {
 
     if (_b == null)  _b = retrieveB();
     return _b;
  }

  String retrieveA() { return "asdfasdf";}
  Integer retrieveB() { return new Integer(42);}
}