classic Java pitfall

getting null because of this

    public void setIsActive(Boolean isActive) {
        isActive = isActive; 
    }

explain to me what is happening vs this corrected code

    public void setIsActive(Boolean isActive) {
        this.isActive = isActive;
    }

ChatGPT zei:
Great question — and a classic Java pitfall.

Here’s exactly what's going wrong and how the fix solves it.

❌ Broken Code
java

public void setIsActive(Boolean isActive) {
    isActive = isActive;
}

✅ What you intended:
You meant to assign the value of the method parameter (isActive) to the instance variable isActive.

❌ What actually happens:
The code isActive = isActive; assigns the parameter to itself.
You're setting the method's local variable (isActive) equal to itself — not touching the field at all.

This means the instance field remains null, and that's why you're seeing null when you try to use or serialize the object.

✅ Correct Code
java

public void setIsActive(Boolean isActive) {
    this.isActive = isActive;
}

✔️ What this does:

• this.isActive refers to the field of the object.

• isActive refers to the parameter.

You're now assigning the value from the parameter to the object's field — which is exactly what you want in a setter.

🧠 Rule of Thumb

• Always use this.fieldName when:

The method parameter has the same name as the field.

You want to disambiguate between them.