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autoboxing in vectors

rakhee gupta
Ranch Hand

Joined: May 01, 2008
Posts: 43

I have a doubt regarding autoboxing.
When we try to add an primitive to vectors doesn't autoboxing automatically converts the primitive to wrapper class?
like is this not a valid statement:
2) Vector v=new Vector();

What are rules of autoboxing.When it comes into play?
Thanks in advance.
Bhanurekha Chintagunta

Joined: Jul 28, 2008
Posts: 4
Vector take any Object if we don't specify the type like Vector<object_type> . all the primitives that are added will converted to wrapper classes. Check your have compiler if the version has autoboxing?

import java.util.*;
public class D {

class sub {

sub() {
System.out.println("created a sub");

public String toString() {
return "Object::sub";

D() {
Vector v = new Vector();
v.addElement("some string");
v.addElement(new sub());
for (Object i : v) {
System.out.println("Value:: " + i + "\t Class:: " + i.getClass().getName());

public static void main(String[] args) {
D sub = new D();

the above code prints

Value:: 99 Class:: java.lang.Integer
Value:: some string Class:: java.lang.String
Value:: Object::sub Class:: D$su

Milan Sutaria
Ranch Hand

Joined: Jul 10, 2008
Posts: 122
it applies to all the Collection (concrete) (sub-)classes maps,sets list etc

SCJP 6 83%
I agree. Here's the link:
subject: autoboxing in vectors
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