Quick Answer
The answer is a compilation error because byte cannot be assigned int. When Java evaluates `b + 1`, it performs byte addition type promotion, widening the `byte` operand to an `int` before the addition occurs. The resulting value is an `int`, and attempting to store it back into a `byte` variable without an explicit cast triggers an "incompatible types: possible lossy conversion from int to byte" error. On the Oracle Java Foundations 1Z0-811 exam, this question tests your understanding of binary numeric promotion and implicit narrowing, a classic trap where candidates forget that arithmetic operations on `byte`, `short`, or `char` always promote to `int`. A reliable memory tip: "Byte math becomes int; you must cast to fit it back."
This 1Z0-811 practice question tests your understanding of primitives, strings and operators. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Given: byte b = 10; b = b + 1; Which statement is true?
The value of b becomes 11.
Why wrong: Does not compile.
b is automatically widened to int then assigned back without error.
Why wrong: No implicit narrowing.
Compilation error because byte cannot be assigned int.
b+1 is int, needs explicit cast.
The expression b+1 results in a byte.
Why wrong: Result is int.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Compilation error because byte cannot be assigned int.
In Java, the expression `b + 1` performs binary numeric promotion, widening the `byte` operand to `int` before addition. The result is an `int` (11), which cannot be implicitly assigned back to a `byte` variable without a cast. Therefore, `b = b + 1;` causes a compilation error: 'incompatible types: possible lossy conversion from int to byte'. Option C correctly identifies this error.
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.
The value of b becomes 11.
Why it's wrong here
Does not compile.
b is automatically widened to int then assigned back without error.
Why it's wrong here
No implicit narrowing.
Compilation error because byte cannot be assigned int.
Why this is correct
b+1 is int, needs explicit cast.
Related concept
Read the scenario before looking for a memorised answer.
The expression b+1 results in a byte.
Why it's wrong here
Result is int.
Common exam traps
The trap here is that candidates often forget that arithmetic operations on `byte` (or `short` or `char`) automatically promote the result to `int`, and they mistakenly assume the assignment is valid without a cast.
Detailed technical explanation
Java's binary numeric promotion (JLS §5.6.2) dictates that when a `byte` is used in an arithmetic operation with an `int` literal, both operands are promoted to `int`. The result is an `int`, which has a wider range (32-bit) than `byte` (8-bit). To assign it back, an explicit cast `(byte)` is required, which truncates the value to the lower 8 bits. This behavior prevents silent data loss and is a common source of compile-time errors in mixed-type arithmetic.
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.
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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: Compilation error because byte cannot be assigned int. — In Java, the expression `b + 1` performs binary numeric promotion, widening the `byte` operand to `int` before addition. The result is an `int` (11), which cannot be implicitly assigned back to a `byte` variable without a cast. Therefore, `b = b + 1;` causes a compilation error: 'incompatible types: possible lossy conversion from int to byte'. Option C correctly identifies this error.
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. Given: byte b = 10; b = b + 1; What is the result?
hardWhy C: In Java, arithmetic operations on byte promote the result to int. Assigning an int to a byte without a cast causes a compilation error.
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Last reviewed: Jun 25, 2026
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