# Interface

A contract describing behavior that implementing classes agree to provide.

## What is **Interface** in Java?

**Interface** — A contract describing behavior that implementing classes agree to provide.

```java
interface Printable {
    default String format() {
        return "Ready";
    }
}

class Ticket implements Printable {
}
```

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

Updated: September 27, 2026

## In other subjects

- [Interface in C#](https://www.ask-codey.com/glossary/interface-c-sharp)
- [Interface in OOP](https://www.ask-codey.com/glossary/interface-oop)

Source: https://www.ask-codey.com/glossary/interface