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Oracle Certified Professional: Java SE Developer 1Z0-831 (Java SE 25) · Domain 2: Controlling program flow

Unreachable code and definite assignment compile errors

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Last reviewed September 25, 2026 · Leer en español

The Java compiler performs flow analysis on every method. Two of its checks produce errors that the exam loves: statements that can never run (unreachable code), and local variables that might be read before they have a value (definite assignment). Both are compile-time errors, not warnings, so a question that seems to be about output may really be about whether the code compiles.

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