How to Print Unique Object Identity for Debugging in Java

How can I print the unique object identity for debugging purposes in Java?

System.identityHashCode(object); // Returns the unique hash code for the given object.

In Java, every object has a unique identity that allows developers to distinguish between different instances. When debugging, accessing this unique identity can provide valuable insight, particularly when tracking object interactions and ensuring proper memory usage.

class TestObject {
    private String name;
    public TestObject(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return "TestObject{ name='" + name + "', identityHashCode='" + System.identityHashCode(this) + "' }";
    }
}

public static void main(String[] args) {
    TestObject obj1 = new TestObject("First");
    TestObject obj2 = new TestObject("Second");
    System.out.println(obj1);
    System.out.println(obj2);
} // Output: Different identities for each object.

Causes

• Improper object comparison when debugging
• Need to differentiate between similar-looking objects
• Identifying memory leaks or unusual object behaviors

Solutions

• Use `System.identityHashCode(object)` to retrieve the unique hash code for an object.
• Override the `toString()` method in your classes to include unique identifier information for better readability.
• Utilize a logging framework to log object identities along with their states using structured logging.

Mistake: Using `equals()` method for object identity comparison instead of hash code.

Solution: Utilize `System.identityHashCode(object)` for identity checks.

Mistake: Neglecting to log the object state along with the identity during debugging sessions.

Solution: Log both identity and state information to assist in tracking behaviors.