C++ Pointers vs Java References

In this article, we will show you the difference between C/C++ pointers and Java references. C/C++ use pointers to manually control how memory is used and accessed. Java, on the other hand, does not support pointers and uses references instead, which manage memory automatically.

Pointer in C/C++

A pointer is a variable that holds the address of another variable in memory. It gives you direct access to that memory, which is powerful but can lead to errors if not used carefully.

Syntax

Here's the syntax where we declare a pointer with an asterisk(*) and assign it the address of a variable using the & operator.

int x = 10;
int* ptr = &x;  // ptr stores the address of x

Key Features of Pointers

Pointers in C or C++ have the following key features:

• They can point to any memory location.
• You can change their value using pointer arithmetic (add or subtract).
• They need careful handling to avoid errors like crashes or memory leaks.
• They allow you to manage memory manually with malloc, free, or new, delete.

Example

In this C++ example, we declare an integer x with a value of 5 and a pointer ptr that stores its address. We display the value of x using the pointer, then modify x indirectly by dereferencing the pointer (*ptr) and changing its value to 10. Finally, we print the updated value of x.

#include <iostream>
using namespace std;

int main() {
    int x = 5;           // Declare an integer variable and initialize it
    int* ptr = &x;       // Declare a pointer that stores the address of x

    cout << "Value of x: " << x << endl;       // Display the value of x
    cout << "Address of x: " << &x << endl;   // Display the memory address of x
    cout << "Value stored in pointer ptr: " << *ptr << endl;  // Dereference ptr to access value of x

    *ptr = 10;  // Modify the value of x using the pointer

    cout << "New value of x after modification: " << x << endl;  // Display the updated value of x

    return 0;
}

After running the program, the output shows the following:

Value of x: 5
Address of x: 0x7ffd8e2101d4
Value stored in pointer ptr: 5
New value of x after modification: 10

References in Java

In Java, references are used to access objects stored in memory. Unlike pointers in C/C++, they don't show memory addresses or allow pointer arithmetic. All non-primitive types, such as objects and arrays, are accessed using references, while primitive types like int, char, and float are accessed directly.

Syntax

Below is the syntax that creates a new object of ClassName and assigns its reference to the variable referenceName.

ClassName referenceName = new ClassName();

Key Features of References in Java

References in Java have the following key features:

• They always point to objects stored in heap memory.
• Pointer arithmetic and direct memory manipulation are not possible with references.
• Memory is automatically managed by the Garbage Collector.
• References are safer and more secure than pointers in other languages.

Example

In this example, we use Java references to create and work with objects. We declare a reference to a string, assign it a value, and display it. The reference points to the object's memory location, allowing us to access its data.

public class ReferenceExample {
    public static void main(String[] args) {
        // Declaring a reference to a String object
        String greeting;

        // Assigning a value to the reference
        greeting = "Welcome to Java Programming!";

        // Displaying the value of the String object through the reference
        System.out.println(greeting);
    }
}

The output shows how a Java reference is used to store and display the value of an object.

Welcome to Java Programming!

Key Differences Between C/C++ Pointers and Java References

The following table highlights the main differences between C/C++ pointers and Java references.