Wednesday, 17 May 2017

Java Tutorial: Generics in java | Java Generics [The extends wildcard boundary]


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Java Tutorial: Generics in java | Java Generics [The extends wildcard boundary] 
A.java
public class A
{
    private int value = 10;

    public int getValue()
    {
        return value;
    }

    public void setValue(int value)
    {
        this.value = value;
    }

}
B.java
public class B extends A
{

}
C.java
public class C extends A
{

}
GenericDemo.java
import java.util.ArrayList;
import java.util.List;

public class GenericDemo
{

    public static void main(String[] args)
    {
        GenericDemo genericDemo = new GenericDemo();

        List<A> listA = new ArrayList<A>();
        listA.add(new A());
        genericDemo.processElements(listA);

        List<B> listB = new ArrayList<B>();
        listB.add(new B());
        genericDemo.processElements(listB);

        List<C> listC = new ArrayList<C>();
        listC.add(new C());
        genericDemo.processElements(listC);
    }

    public void processElements(List<? extends A> list)
    {
        for (A a : list)
        {
            System.out.println(a.getClass());
            System.out.println("value =  "+a.getValue());
            System.out.println("------------");
        }
    }

}
Output
class A
value =  10
------------
class B
value =  10
------------
class C
value =  10
------------
Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/GenericsDemo_extends_wildcard_boundary_App.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/GenericsDemo_extends_wildcard_boundary_App

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

See also:
  • All JavaEE Viedos Playlist
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  • All JAVA EE Links
  • Servlets Tutorial
  • All Design Patterns Links
  • JDBC Tutorial
  • Java Collection Framework Tutorial
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