Interface with default method - Java Object Oriented Design

Java examples for Object Oriented Design:interface

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Description

Interface with default method

Demo Code

interface Movable {
  void setX(double x);

  void setY(double y);

  double getX();/*  w  w w  . j a  v  a  2s.  c  o m*/

  double getY();

  // A default method
  default void move(double deltaX, double deltaY) {
    double newX = getX() + deltaX;
    double newY = getY() + deltaY;
    setX(newX);
    setY(newY);
  }
}

class Pen implements Movable {
  private double x;
  private double y;

  public Pen() {
    // By default, the pen is at (0.0, 0.0)
  }

  public Pen(double x, double y) {
    this.x = x;
    this.y = y;
  }

  public void setX(double x) {
    this.x = x;
  }

  public void setY(double y) {
    this.y = y;
  }

  public double getX() {
    return x;
  }

  public double getY() {
    return y;
  }

  public String toString() {
    return "Pen(" + x + ", " + y + ")";
  }
}

public class Main {
  public static void main(String[] args) {
    // Create a Pen and assign its reference to a Movable variable
    Movable p1 = new Pen();
    System.out.println(p1);

    // Move the Pen using absolute cocordinates
    p1.setX(10.0);
    p1.setY(5.0);
    System.out.println(p1);

    // Move the Pen using relative cocordinates
    p1.move(5.0, 2.0);
    System.out.println(p1);
  }
}

Result


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