Set using generics

[Ravinder Singh]

Hi,

import java.util.*;
 
class TestMaps {
public static void main (String args[]) {
TreeSet map = new TreeSet();
System.out.println("Adding one.. " + map.add("one"));
map.add("two");
map.add("three");
map.add("four");
System.out.println("Adding one again.. " +map.add("one"));
Iterator it = map.iterator();
while(it.hasNext()) {
System.out.print(it.next() + " ");
}
}
}

Q. Why does the code above compiles with the following warning??

Note: TestMaps.java uses unchecked or unsafe operatio
Note: Recompile with -Xlint:unchecked for details.

--------------
Ravinder

[Joshua Smith]

Ravinder-

I would guess that the warning you are getting relates to the fact that the collections and interator that you are using aren't type safe. Try making your TreeSets and your Iterator type safe and I think you'll see the warning disappear.

import java.util.*;
 
class TestMaps {
public static void main (String args[]) {
TreeSet<String> map = new TreeSet<String>();
System.out.println("Adding one.. " + map.add("one"));
map.add("two");
map.add("three");
map.add("four");
System.out.println("Adding one again.. " +map.add("one"));
Iterator<String> it = map.iterator();
while(it.hasNext()) {
System.out.print(it.next() + " ");
}
}
}
 

Hope that helps.
Joshua Smith

[Ravinder Singh]

Thanks Joshua..
The warnings disappear if I change the statement for TreeSet instantiation to: TreeSet<String> map = new TreeSet<String>();

-----------
Ravinder

[Pavel Kubal]

For the next time...compiler told you.

"Recompile with -Xlint:unchecked for details."

Sometimes it is useful to do, what compiler tells you.