📚 Topic Summary
In Java, when you pass an object as a parameter to a method, you're actually passing a reference to that object, not a copy of the object itself. Think of it like giving someone the address to your house, rather than building them an exact replica. If the method modifies the object (changes the values of its fields), these changes are reflected in the original object that was passed in. This is because both the method and the calling code are working with the same object in memory. This behavior is different from passing primitive types (like `int` or `boolean`), where changes inside the method do not affect the original variable.
Understanding object references is crucial for avoiding unexpected side effects and writing robust Java code. This unplugged activity is designed to help you visualize and internalize this fundamental concept without needing a computer!
🧠 Part A: Vocabulary
Match the term with its correct definition:
| Term |
Definition |
| 1. Object Reference |
A. A blueprint for creating objects. |
| 2. Object |
B. A variable that stores the memory address of an object. |
| 3. Method |
C. A block of code that performs a specific task. |
| 4. Parameter |
D. A specific instance of a class. |
| 5. Class |
E. A value passed to a method when it is called. |
Answers: 1-B, 2-D, 3-C, 4-E, 5-A
✍️ Part B: Fill in the Blanks
Complete the following paragraph using the words provided: reference, memory, object, original, copy.
When passing an ___________ to a method in Java, you are actually passing a __________ to its location in __________. This means changes made to the object inside the method will affect the ___________ object outside the method. You are not passing a __________ of the object.
Answer: object, reference, memory, original, copy
🤔 Part C: Critical Thinking
Explain a situation where modifying an object through a method using a reference parameter can be helpful. Then, describe a scenario where this could lead to unintended consequences. How can you avoid these unintended consequences?