Java Collections

[Aruna Balasuriya]

import java.util.*;

public class Test {

public static void main(String[] args) {

List x = new ArrayList<String>();
x.add("Hello");
x.add(new Integer(5));
}


}

Though the type of ArrayList mark as String it accepts Integers.How ?

[Vijitha Kumara]

Aruna Balasuriya wrote:....
Though the type of ArrayList mark as String it accepts Integers.How ?

Hi Aruna, Welcome to JavaRanch

Though it compiles you get an unchecked warning as the compiler looks at the reference type which is of List (raw type) hence not able to do the type checking.

[Prasanna N Venkatesan]

Hey..

Are you expecting an error?

You have used List x = new ArrayList<String>(); which means the list x can accept element of any datatype. If you specifically want to add elements of string type then you have to modify it as:


List<String> x = new ArrayList<String>();

[Embla Tingeling]

Aruna Balasuriya wrote:
List x = new ArrayList<String>();

It should look like this,

List<String> x = new ArrayList<String>();

Otherwise x is a "raw" List and you can enter any object.