API / Apache Velocity Interview questions

What is strict reference mode in Velocity, and how does it differ from the default lenient mode?

By setting runtime.references.strict to true, Velocity switches from silently printing undefined references as literal text to throwing a MethodInvocationException (or similar) as soon as an undefined variable or a failed method/property lookup is hit.

Aspect	Lenient (default)	Strict
Undefined reference	Prints literal text, e.g. $foo	Throws an exception
Typos / renamed getters	Fail silently, easy to miss	Fail loudly during testing
Best suited for	Production resilience, bulk generation jobs	Development and CI, catching mistakes early

engine.setProperty("runtime.references.strict", "true");

A common pattern is to run strict mode in development and integration tests, where a broken reference should fail a build, while keeping lenient mode in production, where you'd rather show a slightly broken page than a hard 500 error from one bad record.

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What does Velocity do with an undefined reference when strict mode is enabled? It prints the literal reference text, same as default

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It throws an exception instead of printing the reference literally

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It substitutes an empty string automatically

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It logs a warning but does nothing else

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Which environment is strict mode most commonly recommended for? Production, to maximize resilience

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Development and CI, to catch broken references early

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Neither environment; strict mode is deprecated

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Only inside Velocimacro library files

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API / Apache Velocity Interview questions

What is strict reference mode in Velocity, and how does it differ from the default lenient mode?

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