What happens if the argument you want to pass is an object instead of a primitive?

[sonali patil]

please can anyone answer me........

[Jaikiran Pai]

Irrespective of whether the parameter is primitive or object, it will get passed to the method which accepts it. Did you mean to ask something else?

[Sachin Dimble]

Hi Sonali,
When argument is of Object type, a copy of reference(on stack) get created which points to same object(on heap) and which can modify that object as it points to same mem. allocation.
e.g.
Obj o=new Obj();
o.somevar=23;
S.o.p(o.somevar); //will print the 23
method(o);
S.o.p(o.somevar); //will print the 12
//somewhere in class
void method(Object o)
{
o.somevar=12;
}

I Hope this will suffice.....

-Sachin!!!

[sonali patil]

thank you very much jaikiran & sachin sir

[Sachin Dimble]

Hey You know me

May i know you are from which batch?

-Sachin!!!

[fred rosenberger]

To be more precise, you do not actually pass an object into a method. nor do you pass a primitive.

with primitives, you pass a COPY of the VALUE. nothing that changes the value inside the method will effect the value outside the method.

With objects, it actually works the same way. That is becuase your variable does not hold an object, but a REFERENCE TO and object - effectively an address (or a pointer, for you C folk). you pass a COPY OF THE VALUE of the reference. if, inside the method, you change where the method's copy points to, you will not change what the outer reference refers to. it still points to the same old place.

however, if you use the inner reference to alter the object it refers to, then that will be reflected in what the outer reference points to (since it points to the same place).

[An Sush]

its always a copy/alias of the object thats passed.

---------------------------------------------------
Data Type of the
Formal Parameters Value Passed
---------------------------------------------------
Primitive data types Primitive data value
Class type Reference value
Array type Reference value
---------------------------------------------------


Array Elements as Primitive Data Values:

public class FindMinimum {
 
    public static void main(String[] args) {
        int[] dataSeq = {6,4,8,2,1};
 
        int minValue = dataSeq[0];
        for (int index = 1; index < dataSeq.length; ++index)
            minValue = minimum(minValue, dataSeq[index]);            // (1)
 
        System.out.println("Minimum value: " + minValue);
    }
 
    public static int minimum(int i, int j) {                        // (2)
        return (i <= j) ? i : j;
    }
}

Output from the program:
Minimum value: 1


Array Elements as Object Reference Values:

public class FindMinimumMxN {
 
    public static void main(String[] args) {
        int[][] matrix = { {8,4},{6,3,2},{7} };                // (1)
 
        int min = findMinimum(matrix[0]);                      // (2)
        for (int i = 1; i < matrix.length; ++i) {
            int minInRow = findMinimum(matrix[i]);             // (3)
            if (min > minInRow) min = minInRow;
        }
        System.out.println("Minimum value in matrix: " + min);
    }
 
    public static int findMinimum(int[] seq) {                 // (4)
        int min = seq[0];
        for (int i = 1; i < seq.length; ++i)
            min = Math.min(min, seq[i]);
        return min;
    }
}

Output from the program:
Minimum value in matrix: 2