Quick Answer
The answer is EL. This output results from the combination of `String.join` and `substring` behavior in Java: `String.join("", "H", "E", "L", "L", "O")` concatenates the individual strings with an empty delimiter, producing "HELLO", and then calling `substring(1, 3)` extracts characters from index 1 (inclusive) to index 3 (exclusive), yielding "EL". On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this question tests your understanding of how `String.join` handles varargs and empty delimiters, paired with the zero-based indexing of `substring`. A common trap is miscounting indices or forgetting that `substring` excludes the end index, leading to answers like "HEL" or "ELL". Remember the memory tip: "join glues with what you give it, substring counts from zero and stops before the end."
This 1Z0-829 practice question tests your understanding of handling date, time, text, numeric and boolean values. 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.
Refer to the exhibit.
public static void main(String[] args) {
String s = "Hello".toUpperCase().substring(1, 3);
System.out.println(s);
}What is the output?
Refer to the exhibit.
public static void main(String[] args) {
String s = "Hello".toUpperCase().substring(1, 3);
System.out.println(s);
}EL
Correct substring indices.
HEL
Why wrong: substring(1,3) excludes index 3.
ELLO
Why wrong: That would be substring(1).
HELL
Why wrong: Includes index 0? No.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
EL
The code uses `String.join("", "H", "E", "L", "L", "O")` which concatenates the elements with an empty delimiter, resulting in "HELLO". Then `substring(1, 3)` extracts characters from index 1 (inclusive) to index 3 (exclusive), yielding "EL". Option A is correct.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
EL
Why this is correct
Correct substring indices.
Related concept
Read the scenario before looking for a memorised answer.
HEL
Why it's wrong here
substring(1,3) excludes index 3.
ELLO
Why it's wrong here
That would be substring(1).
HELL
Why it's wrong here
Includes index 0? No.
Common exam traps
The trap here is that candidates often forget the end index of `substring` is exclusive, leading them to include an extra character, or they miscompute the join result by overlooking the empty delimiter.
Detailed technical explanation
In Java, `String.join` uses an internal `StringJoiner` to concatenate elements with the specified delimiter. The `substring` method is based on the original string's character array, and its end index is exclusive, a common source of off-by-one errors. This behavior is consistent across all Java versions and is critical for text manipulation tasks like parsing log files or extracting substrings from formatted data.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Handling Date, Time, Text, Numeric and Boolean Values — study guide chapter
Learn the concepts, then practise the questions
Handling Date, Time, Text, Numeric and Boolean Values practice questions
Targeted practice on this topic area only
All 1Z0-829 questions
509 questions across all exam domains
Oracle Certified Professional Java SE 17 Developer 1Z0-829 study guide
Full concept coverage aligned to exam objectives
1Z0-829 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise 1Z0-829 questions linked to Handling Date, Time, Text, Numeric and Boolean Values.
Practise 1Z0-829 questions linked to Controlling Program Flow.
Practise 1Z0-829 questions linked to Utilizing Java Object-Oriented Approach.
Practise 1Z0-829 questions linked to Handling Exceptions.
Practise 1Z0-829 questions linked to Working with Arrays and Collections.
Practise 1Z0-829 questions linked to Working with Streams and Lambda Expressions.
Practise 1Z0-829 questions linked to Java Platform Overview and Packaging.
Practise 1Z0-829 questions linked to Java I/O API and Securing Applications.
Practise 1Z0-829 questions linked to 1Z0-829 fundamentals.
Practise 1Z0-829 questions linked to 1Z0-829 scenario.
Practise 1Z0-829 questions linked to 1Z0-829 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Handling Date, Time, Text, Numeric and Boolean Values — This question tests Handling Date, Time, Text, Numeric and Boolean Values — Read the scenario before looking for a memorised answer..
The correct answer is: EL — The code uses `String.join("", "H", "E", "L", "L", "O")` which concatenates the elements with an empty delimiter, resulting in "HELLO". Then `substring(1, 3)` extracts characters from index 1 (inclusive) to index 3 (exclusive), yielding "EL". Option A is correct.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 11, 2026
This 1Z0-829 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-829 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.