package runthis;

/**
*
* @author dt120194
*/
public class Person {
public Person() {
System.out.println(” I am a Person “);
}
}
class Employee extends Person {
public Employee() {
System.out.println(” I am an Employee “);
}
}

class Banker extends Employee {
public Banker() {
System.out.println(” I am a Banker “);
}
}
class Bubba extends Banker {
public Bubba() {
System.out.println(” I am in Bubba “);
}
}

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/

package runthis;

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

/**
*
* @author dt120194
*/
public class Main {

/**
* @param args the command line arguments
*/
public static void main(String[] args) {

// To Illustrated bounded wildcard.
List<Number> abc = new ArrayList<Number>();
List<Integer> def = Arrays.asList(3,3,4,5,6,6,6,6);
doAComparision(def);
System.out.println(“\n\n\n”);
abc.add(6);
abc.add(7);
doAComparision(abc); // works.
List<Double> ghi = Arrays.asList(3.9, 3.0);
// helloStudy(ghi); // This BREAKS!!

// TO illustrate ? extends
List<Person> person = new ArrayList<Person>();
List<Employee> emp = new ArrayList<Employee>();
List<Banker> banker = new ArrayList<Banker>();
List<Bubba> cust = new ArrayList<Bubba>();
List<Object> genObject = new ArrayList<Object>();

// THese will all work… since the wild card says.
// Any thing that extends Person.
testPersonWithExtends(person);
testPersonWithExtends(emp);
testPersonWithExtends(banker);

// Testing the testBankerWithExtends.
// testBankerWithExtends(person); // !! THis will break.. since it does not extend from Employee
testBankerWithExtends(emp);
testBankerWithExtends(banker);

// Testing testPersonWithSuper.
testEmployeeWithSuper(person);
testEmployeeWithSuper(emp);
// This breaks because banker is a subclass of Employee
// testEmployeeWithSuper(banker);

// Testing testBankerWithSuper
testBankerWithSuper(genObject);
testBankerWithSuper(person);
testBankerWithSuper(emp);
testBankerWithSuper(banker);
// The following will break, but the above three pass
// Since Banker and all its super class.
// testBankerWithSuper(cust); < == This is Broken

}

private static void doAComparision(List<? extends Number> def) {
for(Number i : def) {
System.out.println(” Integer List : ” + i.toString());
}
}

private static void helloStudy(List<? super Integer> def) {
for(Object i : def) {
System.out.println(” Integer List : ” + i.toString());
}
}

private static void testPersonWithExtends(List <? extends Person> h) {
System.out.println(” I am in testPersonWithExtends”);
}

private static void testBankerWithExtends(List <? extends Employee> h) {
System.out.println(” I am in testBankerWithExtends”);
}

private static void testEmployeeWithSuper(List <? super Employee> h) {
System.out.println(” I am in testPersonWithSuper”);
}

private static void testBankerWithSuper(List <? super Banker> b) {
System.out.println(” I am in testBankerWithSuper”);
}
}