Pointers in Minitab

Java does not have direct pointer manipulation like in C or C++. Instead, it uses references for objects. However, we can demonstrate a similar concept using object references and primitive wrapper classes.

public class Pointers {
    // This method won't change the value of num in the calling method
    public static void zeroValue(Integer num) {
        num = 0;
    }

    // This method will change the value of the Integer object
    public static void zeroReference(Integer[] numRef) {
        numRef[0] = 0;
    }

    public static void main(String[] args) {
        Integer i = 1;
        System.out.println("initial: " + i);

        zeroValue(i);
        System.out.println("zeroValue: " + i);

        // We use an array to simulate a pointer to the Integer object
        Integer[] iRef = {i};
        zeroReference(iRef);
        i = iRef[0];
        System.out.println("zeroReference: " + i);

        // In Java, we can't print memory addresses directly
        // But we can print the hashcode of the object
        System.out.println("object hashcode: " + System.identityHashCode(i));
    }
}

In this Java example, we demonstrate a concept similar to pointers using object references.

1. The zeroValue method takes an Integer parameter. In Java, Integer is an object wrapper for the primitive int type. When we pass i to zeroValue, Java creates a new Integer object with the same value. Changes to this new object don’t affect the original i in main.

2. The zeroReference method takes an Integer array as a parameter. We use this array to simulate a pointer to our Integer object. By modifying the first element of this array, we can change the value of the original Integer object.

3. In the main method, we first call zeroValue, which doesn’t change the original i. Then we create an array containing i, pass this array to zeroReference, and update i with the changed value.

4. Java doesn’t allow direct access to memory addresses like in some other languages. Instead, we use System.identityHashCode() to get a unique identifier for the object, which serves a similar purpose in this demonstration.

When you run this program, you’ll see output similar to this:

initial: 1
zeroValue: 1
zeroReference: 0
object hashcode: 1956725890

This example shows that zeroValue doesn’t change the i in main, but zeroReference does because it has a reference to the actual Integer object.

Remember, while this example demonstrates a concept similar to pointers, Java’s memory management and reference system work differently from languages with explicit pointer manipulation.