A SIMPLE EXAMPLE ABOUT GENERICS IN JAVA EXPLAINS ABOUT TYPE SAFETY, TYPE CASTING AND POLYMORPHISM

import java.util.*;

public class Generics{

public static void main(String args[])

{

//generic version of ArrayList

ArrayList<String> l=new ArrayList<String>();

List<String> l2=new ArrayList<String>();

l2.add("list reference");

Collection<String> l3=new ArrayList<String>();

l3.add("collection reference");

//ArrayList<int> l1=new ArrayList<int>();

//List<Object> l4=new ArrayList<String>();

l.add("ramu");

l.add("dayina");

l.add("10");  //CE Gene.java:11: cannot find symbol l.add(10);//CEsymbol:   method add(int)  location: class ArrayList<String>1 error

System.out.println(l);

System.out.println(l2);

System.out.println(l3);

 //Collection(I)list(I) are the parent interfaces so they can hold the child references 

List<Integer> l5=new ArrayList<Integer>();

l5.add(100);

List<Integer> l6=new LinkedList<Integer>();

l6.add(101);

List<Integer> l7=new Vector<Integer>();

l7.add(102);

List<Integer> l8=new Stack<Integer>();

l8.add(103);

System.out.println(l5);System.out.println(l6);System.out.println(l7);System.out.println(l8);

}}

D:\Threads>javac Generics.java

 D:\Threads>java Generics

[ramu, dayina, 10]

[list reference]

[collection reference]

[100]

[101]

[102]

[103]