Quick Answer
The answer is 3345. This output results from Java’s strict left-to-right evaluation order: the expression `1 + 2 + "3" + 4 + 5` begins with integer addition, so `1 + 2` yields `3`, then `3 + "3"` triggers string concatenation to produce `"33"`, and every subsequent `+` with an integer becomes string concatenation, appending `"4"` and `"5"` to form `"3345"`. On the Oracle Java Foundations 1Z0-811 exam, this question tests your understanding of operator precedence and type coercion—specifically how the `+` operator shifts from numeric addition to string concatenation the moment a `String` operand appears. A common trap is assuming the entire expression is evaluated as integers first, but Java processes it stepwise from left to right. Remember the memory tip: “Numbers add until a string appears, then everything after is glued.”
This 1Z0-811 practice question tests your understanding of primitives, strings and operators. 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.
What is the output of System.out.println(1 + 2 + "3" + 4 + 5);?
3345
String concatenation after first addition.
12345
Why wrong: Addition is left associative; numbers before string are added.
3"3"45
Why wrong: No quotes printed.
15
Why wrong: Misunderstands concatenation.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
3345
Java evaluates the expression left-to-right. The first operation is `1 + 2`, which is integer addition, yielding `3`. Then `3 + "3"` triggers string concatenation, producing `"33"`. The remaining `+ 4` and `+ 5` are also string concatenations, appending `"4"` and `"5"` to give `"3345"`. The `println` method outputs this string.
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.
3345
Why this is correct
String concatenation after first addition.
Related concept
Read the scenario before looking for a memorised answer.
12345
Why it's wrong here
Addition is left associative; numbers before string are added.
3"3"45
Why it's wrong here
No quotes printed.
15
Why it's wrong here
Misunderstands concatenation.
Common exam traps
The trap here is that candidates assume all `+` operators behave the same way, failing to recognize that the presence of a string literal changes the operator's meaning from arithmetic addition to string concatenation, and that left-to-right evaluation means the first two numbers are added as integers before the string is encountered.
Detailed technical explanation
Java's `+` operator is overloaded: it performs integer addition when both operands are numeric, and string concatenation when at least one operand is a `String`. The evaluation is strictly left-associative, so the type of the intermediate result changes from `int` to `String` after the first string operand is encountered. This behavior is defined in JLS §15.18.1 and §15.18.2, and it's a common source of off-by-one logic errors in logging or SQL query building where mixed types appear.
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
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FAQ
Primitives, Strings and Operators — This question tests Primitives, Strings and Operators — Read the scenario before looking for a memorised answer..
The correct answer is: 3345 — Java evaluates the expression left-to-right. The first operation is `1 + 2`, which is integer addition, yielding `3`. Then `3 + "3"` triggers string concatenation, producing `"33"`. The remaining `+ 4` and `+ 5` are also string concatenations, appending `"4"` and `"5"` to give `"3345"`. The `println` method outputs this string.
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.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. What is the output?
easyWhy A: The code `System.out.println("Result: " + 2 + 3);` uses string concatenation. In Java, the `+` operator is left-associative, so the expression is evaluated as `("Result: " + 2) + 3`. First, the integer `2` is converted to the string `"2"` and concatenated with `"Result: "` to form `"Result: 2"`. Then, the integer `3` is converted to the string `"3"` and concatenated, producing `"Result: 23"`. Option A is correct because the output is the string `"Result: 23"`.
Variation 2. What is the result of: System.out.println(10 + 20 + "30");
easyWhy B: In Java, the '+' operator is left-associative. The expression `10 + 20 + "30"` is evaluated as `(10 + 20) + "30"`, which first performs integer addition to get `30`, then concatenates that integer with the string `"30"`, resulting in the string `"3030"`. The `System.out.println` method then prints the string `3030`.
Last reviewed: Jun 25, 2026
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