Assigning value to object reference Java 1.5

[getmeidea]

Hi,

I am using JDK 1.5.
I have a program like this. Here i am directly assigning value to one object.
It does'nt give me any compile time or run time error. In java we dont have access to any object reference. Still this kind of assignment is allowed. What is the reason behind this.

Class Sample{
    public static void main(){
        //Assigning value to object reference itself.
        Integer i = 10;
        System.out.println(i.intValue());
    }
}

But i think it initialise an objects and assigns the given value to object.
How it is implemented ?

[r035198x]

Perhaps you should explain what you mean by

... In java we dont have access to any object reference. ...

[getmeidea]

Perhaps you should explain what you mean by

when i say, Integer i = 10;

here the reference value of i is not set by the value 10. Still it is allowed to write without giving any compile error.

[Nepomuk]

Perhaps you should explain what you mean by...

I think what the OP means is, that 10 is an int, not an Integer and therefore it should be

Integer i = new Integer(10);

Wasn't that something about automatic matching, introduced in JRE 1.5? (I tried it with compilance level 1.3 - it won't work. No problem with compilance level 6.0 however.)

Greetings,
Nepomuk

[dmjpro]

Hi,

I am using JDK 1.5.
I have a program like this. Here i am directly assigning value to one object.
It does'nt give me any compile time or run time error. In java we dont have access to any object reference. Still this kind of assignment is allowed. What is the reason behind this.

Class Sample{
    public static void main(){
        //Assigning value to object reference itself.
        Integer i = 10;
        System.out.println(i.intValue());
    }
}

But i think it initialise an objects and assigns the given value to object.
How it is implemented ?

You can't assign an object reference like this........ :-(
Here what is done ... it is Auto Boxing, introduced in Java 1.5.

Kind regards,
Dmjpro.

[Laharl]

You can't assign an object reference like this........ :-(
Here what is done ... it is Auto Boxing, introduced in Java 1.5.

Kind regards,
Dmjpro.

Basically, in Java 1.5, they added direct comparison between Integer and int (called Auto Boxing), so you don't have to use intValue() and lots of casting anymore, unless you really want to.

[getmeidea]

Basically, in Java 1.5, they added direct comparison between Integer and int (called Auto Boxing), so you don't have to use intValue() and lots of casting anymore, unless you really want to.

By refereng "Autoboxing" i came to know how this statement works.
Thanks to all who made me reply and telling the term "Autoboxing".

[dmjpro]

By refereng "Autoboxing" i came to know how this statement works.
Thanks to all who made me reply and telling the term "Autoboxing".

Sorry for misunderstanding your Question.

Kind regards,
Dmjpro.

[JosAH]

I don't like autoboxing very much; below you'll see an example derived from an
original example by someone else posted in Sun's Java forum quite a while ago:

import java.util.*;
 
public class Autoboxing {
 
    public static void main(String[] args) {
 
        Object foo = new Long(0xcafebabedeadbeefL);
        List<Object> bars = new ArrayList<Object>();
 
        bars.add(bool() ? (Long)foo : (Number)foo);
        bars.add(bool() ? (Long)foo : (Long)foo);
        bars.add(bool() ? (Long)foo : (Double)foo);
        bars.add(bool() ? (Long)foo : ((Long)foo).longValue());
 
        System.out.print("==    :");
        for (Object bar : bars)
            System.out.print(" "+(foo == bar));
        System.out.println();
 
        System.out.print("equals:");
        for (Object bar : bars)
            System.out.print(" "+foo.equals(bar));
        System.out.println();
    }
 
    private static boolean bool() {
        return true;
    }
}

Output:

==    : true true false false
equals: true true false true
 

That's why I don't like autoboxing very much ...

kind regards,

Jos