Pointers in Squirrel

Java doesn’t have direct pointer manipulation like some other languages. Instead, it uses references for objects. However, we can demonstrate similar concepts using object references and primitive wrapper classes.

public class Pointers {

    // This method takes an Integer object, which is passed by reference
    static void zeroRef(Integer num) {
        num = 0;
    }

    // This method takes a MutableInt object, which we'll use to simulate a pointer
    static void zeroMutable(MutableInt num) {
        num.value = 0;
    }

    // A simple mutable integer class to simulate pointer-like behavior
    static class MutableInt {
        int value;
        MutableInt(int value) {
            this.value = value;
        }
    }

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

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

        MutableInt mi = new MutableInt(1);
        zeroMutable(mi);
        System.out.println("zeroMutable: " + mi.value);

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

In this Java example, we demonstrate concepts similar to pointers using object references and a custom mutable class.

The zeroRef method takes an Integer object. In Java, Integer is immutable, so assigning a new value to the parameter doesn’t affect the original variable in the calling method.

The zeroMutable method takes a MutableInt object, which we’ve created to simulate pointer-like behavior. Changes to this object’s value field are reflected in the calling method.

In the main method:

1. We create an Integer object and print its initial value.
2. We call zeroRef, which doesn’t change the original i variable.
3. We create a MutableInt object and call zeroMutable, which does change the object’s value.
4. Finally, we print the hash code of the Integer object, which serves as a unique identifier (similar to a memory address in other languages).

When you run this program, you’ll see output like this:

initial: 1
zeroRef: 1
zeroMutable: 0
hashCode: 1829164700

This demonstrates that zeroRef doesn’t change the original value, but zeroMutable does, similar to how pointers work in other languages. The hash code at the end is a unique identifier for the object, analogous to a memory address.

Remember, Java manages memory automatically and doesn’t provide direct access to memory addresses like some other languages do. This example aims to demonstrate similar concepts within Java’s object-oriented paradigm.