Generic Assignments

[Balaji Bang]

List<Integer> ls1 = new LinkedList<Integer>(); //line 1
		List<String> ls2 = new LinkedList<String>(); //line 2
		List ls3 = new LinkedList(); //line 3
		List ls4 =ls1; //line 4
		ls4.add("Hi");
		ls4.add(1);
		List ls5 =ls2; //line 5
		ls4=ls5;
		List ls6=ls4=ls5;

What happens if we say
List ls4=ls1;
ls1 is of type Integer. After assigning it to ls4 , ls4 is able to hold both String and Integer. And also we are able to assign ls5=ls4.

Please explain...

[Himanshu Gupta]

Yes because raw reference types allows you to add anything which is an Object.

This runs fine because all the Objects are added at runtime and generics are only for compile time.

[Ruben Soto]

When you use raw types you don't have any sort of compile time type safety (which is what generics provides.) When you assign l1 to l4 that's not a problem, but when you add anything to l4 you will get a compiler warning which mentions unsafe operations.

[Ken Truitt]

It is worth noting that as of Java 5, you will get a warning if you
add *anything* to a raw type, even if there was never any generic
type involved.