Java™ Application Development on Linux - Dator

72Chapter 3An Experienced Programmer’s Introduction to Javaand print the objects in the collection to the command window. The first iteratoruses the while loop, the second one uses a for loop, but they both do thesame thing.As of Java 5.0, there is another way to work your way through a collection,one that requires less type casting, but more importantly one that can enforcethe type of objects at compile time.Notice in Example 3.14 that the result of the next() is coerced into typeString. That’s because everything coming from the iterator (via the next()method) comes to us as a generic object. That way an iterator can handle anytype of object, but that also means that it is up to the application program toknow what type should be coming back from the iterator. Any typecasting errorwon’t be found until runtime.With the syntax added in 5.0, not only is there a shorthand in the forloop for looping with an iterator. There is also syntax to tell the compiler explicitlywhat type of objects you are putting into your collection or array so thatthe compiler can enforce that type.Example 3.15 may help to make this clearer.Example 3.15 Using a for loop iteratorimport java.util.*;public classForeign{public static voidmain(String [] args){List loa = Arrays.asList(args);System.out.println("size=" + loa.size());for(String str : loa) {System.out.println("arg=" + str);}} // main} // ForeignHere we build a List from the arguments supplied on the command line.Notice the type name inside of angle brackets (less-than and greater-than signs).