How to write it in Java

Here I have simple code in C++:

Code:

---

include <iostream>
using namespace std;

//method that just changes numbers;
int change(int &initialNumber, int finalNumber){
initialNumber=finalNumber;
}

int main()
{
int anyNumber=5;
change(5, 10);
//now anyNumber refers to 10 not to 5;
cout<<anyNumber;//output will be 10
}

---

}

The problem is How Can I write this in Java:

Code:

---

public class Test{
private static int change(int initialNumber, int finalNumber){
return initialNumber=finalNumber;
}
public static void main(String [] args){
int anyNumber=5;
change(5, 10);
//anyNumber till refers to 5; How to make it refer to the new value
System.out.println(anyNumber);//output is 5
}
}

---

Java uses the call by value parameters passing mechanism; always. What you did in your C++ program can't be done in Java. b.t.w. 5 can not be a reference and any decent C++ compiler will protest against your use.

kind regards,

Jos

You cannot do this in Java. Objects are passed by reference, primitives are not. An int is a primitive, therefore the values of 5 and 10 are passed to the function, not the object anyNumber and value 10.

Further reading: Parameter passing in Java - by reference or by value?

Quote:

---

Originally Posted by Zack

Objects are passed by reference, primitives are not.

---

Nonsense, objects are also passed by value and Java just uses pointers (references) to objects so those references are passed by value.

kind regards,

Jos

Quote:

---

Originally Posted by JosAH

Nonsense, objects are also passed by value and Java just uses pointers (references) to objects so those references are passed by value.

kind regards,

Jos

---

Yes, the references are passed by value, but that's all that matters. The point is, you can treat it is a pointer, more or less. While you cannot set its value in the old function, calls and data setting methods can be made on it.

Example:

Code:

---

        public static void test(someIntClass x, someIntClass y, int z) {
                x = new someIntClass(5);
                y.m_Int = 5;
                z = 5;
        }
        public static void test2() {
                someIntClass a = new someIntClass(4);
                someIntClass b = new someIntClass(4);
                int c = 4;
                test(a,b,c);
                System.out.printf("%d %d %d\n",a.m_Int,b.m_Int,c); // Prints 4 5 4
        }
        private static class someIntClass {
                public int m_Int = 0;
                someIntClass(int x) { m_Int = x; }
        }

---

Apologies for the messy code. Wrote it in 30 seconds... just call test2() first.

About C++ code, there is no problem when I compile it with BloodShed Dev-C++; And about Java:
If there is situation where I have anyNumber=5;
and I have methods:
change(), anyMethod(), and etc... I want to pass anyNumber to these methods and finally want to return new anyNumber value, Whan I need to do? Or I have to initialize new variable each time after passing it to the method:
anyNumber=5;
int newAnyNumber=change(anyNumber);
int newNewAnyNumber=anyMethdo(newAnyNumber);????

About C++ code, there is no problem when I compile it with BloodShed Dev-C++; And about Java:
If there is situation where I have anyNumber=5;
and I have methods:
change(), anyMethod(), and etc... I want to pass anyNumber to these methods and finally want to return new anyNumber value, What I need to do? Or I have to initialize new variable each time after passing it to the method??:
anyNumber=5;
int newAnyNumber=change(anyNumber);
.............//any code......
int newNewAnyNumber=anyMethod(newAnyNumber);????

Quote:

---

Originally Posted by agajantorayev

I want to pass anyNumber to these methods and finally want to return new anyNumber value, Whan I need to do? Or I have to initialize new variable each time after passing it to the method:
anyNumber=5;
int newAnyNumber=change(anyNumber);
int newNewAnyNumber=anyMethdo(newAnyNumber);????

---

Code:

---

public int F(int x) { return x + 1; }
public void Test() {
    int anyNumber = 5; // anyNumber == 5
    anyNumber = F(anyNumber); // anyNumber == 6
    anyNumber = F(anyNumber); // etc...
    anyNumber = F(anyNumber);
    anyNumber = F(anyNumber);
    anyNumber = F(anyNumber); // anyNumber == 10
}

---

All you have to do is assign it to the return value, just as you would in C++.

PS: There is an edit button, no need to repost your post to add a line to it. ;)

Thanks a Lot!! I have just started Learnig Java programming language!! Thanks Guys for your Help!