The answer is 20 because both variables reference the same array object in memory. When you assign an array reference to a new variable, you are not copying the array itself; instead, you are copying the reference, so both variables point to the exact same object. In the code, `y` is assigned the reference of `arr`, meaning any modification through `y`, such as `y[1] = 20`, directly alters the shared array, and `arr[1]` reflects that change. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this tests your understanding of reference semantics versus value semantics, a common pitfall where candidates mistakenly think a new array is created. The trap is assuming assignment creates a copy, but in Java, array assignment is always a reference copy. Remember the mnemonic: "Assign the arrow, not the cargo"—the variable holds a pointer to the object, not the object itself.
1Z0-829 Working with Arrays and Collections Practice Question
This 1Z0-829 practice question tests your understanding of working with arrays and collections. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit.
```java
import java.util.*;
public class Test {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<>();
map.put("X", 10);
map.put("Y", 20);
map.put("Z", 30);
System.out.println(map.get("Y"));
}
}
```
Refer to the exhibit.
```java
import java.util.*;
public class Test {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<>();
map.put("X", 10);
map.put("Y", 20);
map.put("Z", 30);
System.out.println(map.get("Y"));
}
}
```
A
Y=20
Why wrong: The map's toString would show that, but not get method.
B
null
Why wrong: Key "Y" exists, so value is returned, not null.
C
20
The key "Y" maps to 20.
D
Exception
Why wrong: No exception; get returns the value or null if key absent.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
20
The code creates an array of three integers, then assigns the reference of that array to a new variable `y`. Since `y` points to the same array object, modifying `y[1]` changes the second element to 20. The output is `20` because `arr[1]` reflects the same change.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Y=20
Why it's wrong here
The map's toString would show that, but not get method.
✗
null
Why it's wrong here
Key "Y" exists, so value is returned, not null.
✓
20
Why this is correct
The key "Y" maps to 20.
Related concept
Read the scenario before looking for a memorised answer.
✗
Exception
Why it's wrong here
No exception; get returns the value or null if key absent.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think `y = arr` creates a separate copy of the array, leading them to expect `arr[1]` to remain 0, but Java reference assignment means both variables share the same underlying array object.
Trap categories for this question
Command / output trap
The map's toString would show that, but not get method.
Detailed technical explanation
How to think about this question
In Java, arrays are objects, and assigning an array reference (e.g., `int[] y = arr;`) creates a shallow copy of the reference, not a deep copy of the array data. Both `arr` and `y` point to the same heap object, so mutations through either reference are visible to the other. This is a fundamental concept in Java memory management and reference semantics.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 1Z0-829 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Working with Arrays and Collections — This question tests Working with Arrays and Collections — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 20 — The code creates an array of three integers, then assigns the reference of that array to a new variable `y`. Since `y` points to the same array object, modifying `y[1]` changes the second element to 20. The output is `20` because `arr[1]` reflects the same change.
What should I do if I get this 1Z0-829 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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