API / Apache Velocity Interview questions

What is the difference between #set($x = $y) and context.put("x", y) in Java code?

Both make $x resolvable inside the template, but they act at different layers and different times.

Aspect	#set inside .vm	context.put() in Java
Where it runs	During template rendering, inside VTL	Before rendering starts, from application code
Typical use	Short-lived, template-local values and derived expressions	Supplying the original data model to the template
Visibility to Java	Not visible to Java code after rendering	Fully controlled and testable in Java
Scope	Can be block-scoped inside #foreach/#macro	Available for the whole render unless overwritten

// Java: supplies the source data
context.put("price", 19.99);
context.put("qty", 3);

## VTL: derives a local value from it
#set($total = $price * $qty)

Using #set for something that should really come from Java, like a computed business value, is exactly the pattern the "keep logic out of templates" guidance warns against.

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Which statement correctly distinguishes #set from context.put()? #set runs before Java code executes

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#set runs during rendering inside the template; context.put() supplies data before rendering starts

✓ Correct! Well done.

context.put() can only be called from inside a .vm file

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They are functionally identical with no differences

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Why is heavy use of #set for computed business values discouraged? #set is slower than context.put() by design

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It pushes logic that belongs in Java into the template layer

✓ Correct! Well done.

#set cannot handle arithmetic expressions

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#set values are not visible inside #foreach

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API / Apache Velocity Interview questions

What is the difference between #set($x = $y) and context.put("x", y) in Java code?

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