Java Tutorial: Generics in java | Java Generics [Wildcard in Java Generics]

Click here to watch in Youtube :
https://www.youtube.com/watch?v=VawfMZaSWJU&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial: Generics in java | Java Generics [Wildcard in Java Generics] 

Shape.java

public abstract class Shape
{
    abstract void draw();
}

class Circle extends Shape
{
    void draw()
    {
        System.out.println("drawing circle");
    }
}

class Rectangle extends Shape
{
    void draw()
    {
        System.out.println("drawing rectangle");
    }
}

GenericDemo.java

import java.util.ArrayList;
import java.util.List;

public class GenericDemo
{

    public static void main(String args[])
    {
        List<Rectangle> recList = new ArrayList<Rectangle>();
        recList.add(new Rectangle());
        recList.add(new Rectangle());
        drawShapes(recList);

        List<Circle> circleList = new ArrayList<Circle>();
        circleList.add(new Circle());
        circleList.add(new Circle());       
        drawShapes(circleList);
    }

    /*
     * This method accepts only the list contains child class of Shape
     */
    public static void drawShapes(List<? extends Shape> shapeList)
    {
        for (Shape shape : shapeList)
        {
            shape.draw();
        }
    }

}

Output

drawing rectangle
drawing rectangle
drawing circle
drawing circle

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/GenericsDemo-wildcard_App.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/GenericsDemo-wildcard_App

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/539015917c8406e4be671410d713073b3971d1a5/BasicJava/GenericsDemo-wildcard_App/?at=master

See also:

All JavaEE Viedos Playlist

All JavaEE Viedos

All JAVA EE Links

Servlets Tutorial

All Design Patterns Links

JDBC Tutorial

Java Collection Framework Tutorial

JAVA Tutorial

Kids Tutorial