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"));
}
}
```
What is the output?
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"));
}
}
```
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 a HashMap and adds a mapping from key "Y" to value 20. When it retrieves the value for key "Y" using get(), it returns 20. The output is simply the integer 20, not the string "Y=20". Therefore, option C is correct.
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 is that candidates may expect the output to include the key (e.g., "Y=20") because they confuse the return value of get() with an entry's toString() representation. The get() method returns only the value (or null if absent), not a formatted key-value string.
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 a HashMap and adds a mapping from key "Y" to value 20. When it retrieves the value for key "Y" using get(), it returns 20. The output is simply the integer 20, not the string "Y=20". Therefore, option C is correct.
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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