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What Is an Interface?

Discover how interfaces create contracts that classes must fulfill

Understanding Interfaces

An interface is like a contract that defines what methods a class must implement. Think of it as the control panel of a device - it shows you what actions are possible, but each device can implement those actions differently!

Contract

Defines what must be done

Enforcement

Compiler ensures compliance

Flexibility

Each class implements differently

Interface Contract Status

Ready to Create Contract

Select an interface and create an implementation

Choose an Interface to Implement

Each interface represents a contract with different methods

Bicycle Interface Contract4 methods required

interface Bicycle {void changeCadence(int newValue);
void changeGear(int newValue);
void speedUp(int increment);
void applyBrakes(int decrement);
}

Create Interface Implementation

Create a class that implements the Bicycle interface

Interface Contract Code

Live Java code showing interface contracts and implementations

// Interface Definition - The Contract
interface Bicycle {
    // Contract: Must implement this method
    void changeCadence(int newValue);
    // Contract: Must implement this method
    void changeGear(int newValue);
    // Contract: Must implement this method
    void speedUp(int increment);
    // Contract: Must implement this method
    void applyBrakes(int decrement);
}

Contract Activity0/5

Interface implementation progress

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