API / Apache FreeMarker Interview questions

How do you apply default values for missing variables in FreeMarker?

The default-value operator ! supplies a fallback when a variable is missing or null, so the template does not fail: ${nickname!"Guest"} prints the nickname if it exists, otherwise prints "Guest".

<p>Hello, ${user.nickname!"friend"}!</p>
<#assign theme = settings.theme!"light">

It also works with nested property paths, where any segment along the chain might be missing, by wrapping the whole path: ${(user.profile.avatarUrl)!"/default.png"}. This is the idiomatic FreeMarker way to avoid the equivalent of a null-pointer failure without writing an explicit <#if> check for every optional value.

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What does ${nickname!"Guest"} print when nickname is missing?It throws an unrecoverable error

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An empty string always

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The literal text "nickname"

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"Guest"

✓ Correct! Well done.

Why must a nested path like user.profile.avatarUrl be wrapped in parentheses before applying !?Because nested paths are otherwise treated as macros

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So the default applies if any segment in the chain is missing, not just the last one

✓ Correct! Well done.

Parentheses are required by FreeMarker's HTML escaping rules

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Because ! only works on numbers

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What is the purpose of interpolation (${...}) in FreeMarker? List the comparison operators supported in FreeMarker? What are the main use cases of FreeMarker? What are the types in FreeMarker's data model? How do you use the #assign directive? Describe the built-ins available in FreeMarker? How do you access static Java members (static methods, fields, and enum constants) from a FreeMarker template? What is Apache FreeMarker? What is the purpose of the FreeMarker Configuration object? What is the difference between FreeMarker's #switch/#case and a chain of #if/#elseif directives? What is the purpose of the <#if> directive? What are the types of loops available in FreeMarker? What is the difference between #assign and #local? How do you apply default values for missing variables in FreeMarker? Why doesn't FreeMarker allow templates unrestricted access to Java reflection and side-effecting method calls? What is the purpose of the incompatible_improvements setting? Define directive in FreeMarker? Which is generally the better choice for a new project today, FreeMarker or Velocity, and why? What is a FreeMarker template? What is the purpose of the #include directive?

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