A contract in in a Java class is similar to a contract in the real world - In non-technical terms:
It's an agreement that the class will expose certain methods, certain properties, and certain behaviors.
More technical, from here: (bold added by me)
Wouldn't it be nice if all Java classes that you use, including your
own, lived up to their promises? In fact, wouldn't it be nice if you
actually knew exactly what a given class promises? If you agree, read
on [...]
Design by Contract
The Design by Contract (DBC) software development technique ensures
high-quality software by guaranteeing that every component of a system
lives up to its expectations. As a developer using DBC, you specify
component contracts as part of the component's interface. The contract
specifies what that component expects of clients and what clients can
expect of it.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
