Translate an exception in Java

Java interview exercise on Exceptions & validation, difficulty 2 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.

Write class ConfigException extends RuntimeException (constructors for a message, and for a message with a cause) and loadPort(env) that reads "PORT" from the map: missing → ConfigException("PORT is missing"); not a number → ConfigException("PORT must be a number, got <value>") with the NumberFormatException as its cause; otherwise the port as an int.

Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.

More Exceptions & validation in Java

• A custom checked exception
• Parse with a fallback
• try-with-resources
• Collect every validation error
• Retry an action

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