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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.

May 10, 2025 - 10:34
 0
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.

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