# Unchecked Exception

A runtime exception the compiler does not require code to catch or declare.

## What is **Unchecked Exception** in Java?

**Unchecked Exception** — A runtime exception the compiler does not require code to catch or declare.

```java
class Reservation {
    void reserve(int seats) {
        if (seats < 1) {
            throw new IllegalArgumentException("seats");
        }
    }
}
```

Level: Journeyman · [More Java terms at this level](https://www.ask-codey.com/glossary/subjects/java/journeyman)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/unchecked-exception