Polymorphism in Java

Polymorphism means "many forms": the same method call behaves differently depending on the object.

	Compile-time	Runtime
Achieved by	Method overloading	Method overriding
Resolved	By the compiler	By the JVM at runtime
Also called	Static binding	Dynamic method dispatch

Runtime Polymorphism (Overriding)

Java

class Bank { double rate() { return 0; } String name() { return "Bank"; } }
class SBI  extends Bank { @Override double rate() { return 6.8; } @Override String name() { return "SBI"; } }
class HDFC extends Bank { @Override double rate() { return 7.1; } @Override String name() { return "HDFC"; } }

Bank[] banks = { new SBI(), new HDFC() };
for (Bank b : banks)
    System.out.println(b.name() + " interest: " + b.rate() + "%");

SBI interest: 6.8% HDFC interest: 7.1%

Quick Check

Method overriding is an example of…

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