Inheritance [JAVA]

Inheritance is one of two fundamental possibilites to build new classes from existing ones. The other one is aggregation.

extends is the reserved word in java that defines a inheritance between classes:

class B {
  // some constructors,
  // methods and
  // variables,
}

class D extends B {
  // new constructors,
  // methods and
  // variables,
}

D is derived from B; it extends B with new methods, variables and constructors.

If a class does not explicitely extend another class, it implicitely extends the mother of all classes: java.lang.Object.

Synonyms for the new class are

• subclass
• derived class
• child class

Synonyms for the old class are

• superclass
• base class
• parent class

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