Is it possible in java to pass reference of object in Java?

Question

Hello,
I'm relativily new to Java but I have "solid" knowledge in C+ and C# .NET+.
Is it possible in java to pass reference of object in Java? I read some articles about weakreferences, softreferences, etc. but it seems that it's not what I'm looking for.
Here is a little piece of code I wrote:
package Software;
import java.util.Random;
* @author Rodrigue
public class RandomText
    private Random rand = new Random();
    private Thread t;
    private String rText = "Rodrigue";
    public RandomText()
        t = new Thread()
            @Override
            public void run()
                try
                    while(true)
                        UpdateText();
                        sleep(100);
                catch(InterruptedException ex)
        t.start();
    private void UpdateText()
        int i = rand.nextInt();
        synchronized (rText)
            rText = String.valueOf(i);
    public String GetText()
        return rText;
}It's just a class which start a thread. This class updates a text with a random integer 10 times per second.
I would like to get a reference on the String rText (like in C++ ;) yes I know, I must think in Java :D). So, like that, I could get one time the reference, thanks to the GetText function, and update the text when my application will repaint. Otherwise, I always have to call the GetText method ... which is slow, no?
Are objects passed by reference in java? Or, my string is duplicated each time?
Thank you very much in advance!
Rodrigue

Answer 1

disturbedRod wrote:
Ok, "Everything in Java is passed by value. Objects, however, are never passed at all.". Reference of object is passed by value too.
But, how to solve my problem in Java_? I have an object which is continually modified in a thread. From an another side, this object is continually repainted in a form.I'm not sure I totally understand your problem. If you pass a reference to an object, then both the caller and the method point to the same object. Changing the internal state of the object (e.g. by calling a setter method) through one reference will be observed through both references, since they both point to the same object.
No, calling a method is not particularly slow. Especially if it's just a simple getter method that returns the value of a member variable.
If this is happening in a multithreaded context, you'll have to use proper synchronization to ensure that each thread sees the others' changes.