java-object passing by value

[aumkar0406]

Java only follow 'pass by value'..
But not the pass by refference like in c,c++..
In c,c++ we can pass value to other functions by pass by value and pass by address(rfference)..
But in java only pass by value iz pozible..

Any explanation abou it??a detail or a programme illustrating it..

[Norm]

But in java only pass by value is possible.

[pbrockway2]

C is also pass by value.

For Java you might like to read
JavaRanch Campfire - Cup Size: a Story About Variables
JavaRanch Campfire - Pass By Value, Please

[naveenpaul1987]

Guys,

I think pass by value and pass by reference , both possible in Java.

Changes that occurred due to pass by reference will get reflected outside the method. But in case of pass by value changes wont reflected outside the loop.

Please corect me If i am wrong.

If u need any sample code, then please do let me know

[pbrockway2]

But in case of pass by value changes wont reflected outside the loop.

Please corect me If i am wrong.

When people speak of pass by value in Java they are referring to the fact that there will be no change to the value of a variable used as an argument that the caller can see.

int bar = 42;
int foo = bar;
someMethod(foo);
System.out.println(foo == bar); // prints "true" because foo still has the same value

Point bar2 = new Point(42, 666);
Point foo2 = bar2;
someOtherMethod(foo2);
System.out.println(foo2 == bar2); // prints "true" because foo2 still has the same value.

In both cases "true" will be printed. That's because the values of foo and foo2 do not change and cannot change whatever the methods are. If they were equal to bar and bar2 then they will remain so. Methods do not and cannot change the value of variables. That's because a copy of the value of the variable is passed to the method, and the method sees only this value. Java is pass by value.

Of course, lots of other things might change when you call a method. Otherwise methods would be somewhat useless. But the value of variables won't change because the method is only passed a copy of this value.

-----

The links I posted above are well worth reading.

[quad64bit]

I think pass by value and pass by reference , both possible in Java.

Nope, pbrockway2 is correct. Some people might say java is pass by reference when dealing with objects, since you can 'pass' them to methods and it modifies the original, however, java is still passing by value.

[aumkar0406]

@quad64bit-----can we say java is both pass by value and pass by refference

[aumkar0406]

Plz post the sample code...

[quad64bit]

@aumkar0406

can we say java is both pass by value and pass by refference

Nope! because it isn't. It is purely pass by value.

Java is Pass-by-Value, Dammit! - Scott Stanchfield

[JosAH]

This topic shows up again and again, doesn't it?

kind regards,

Jos

[Tolls]

This topic shows up again and again, doesn't it?

kind regards,

Jos

I'm getting flashbacks...

[tnrh1]

Methods do not and cannot change the value of variables. That's because a copy of the value of the variable is passed to the method, and the method sees only this value.

As far as I know variables are saved in the stack.
Everything that is saved in the stack is copied when it passed as a parameter to a method.
But objects(saved in the heap) are not copied and every edit that is done in the method will be vaild after that.
Arrays for example, send them through a method, change a value and you will see that the value has changed after the method.

If I didn't accurate in something correct me :)

[JosAH]

I'm getting flashbacks...

Maybe you have seen the broader perspective, but I haven't; I'm too low level; nuts and bolts so to speak ;-)

kind regards,

Jos

[Norm]

I'm too low level; nuts and bolts

That's a bit above stock and taps and dies.

[JosAH]

That's a bit above stock and taps and dies.

Ha! So I made a promotion? ;-)

kind regards,

Jos

[pbrockway2]

can we say java is both pass by value and pass by refference

We can say anything we want. But if you say that you are wrong. Please read the pages linked to near the start of this thread to see why.