Safely Enabling Types or Methods to Operate on Objects of Various Types

Description

Demo Code

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Main {
  public static void main(String[] args) {
    List<Player> team = new ArrayList<>();
    Player player1 = new Player("A", "AA", 5);
    Player player2 = new Player("B", "BB", 15);
    Player player3 = new Player("C", "CC", 1);
    Player player4 = new Player("D", "DD", 18);
    Player player5 = new Player("E", "EE", 7);

    team.add(player1);//  ww w  .  jav  a  2 s  . c  om
    team.add(player2);
    team.add(player3);
    team.add(player4);
    team.add(player5);

    List objectList = new ArrayList();
    Object obj1 = "none";
    objectList.add(obj1);

    // Create a List that can be of type that is any superclass of Player
    List<? super Player> myTeam = objectList;
    for (Object p : myTeam) {
      System.out.println("Printing the objects...");
      System.out.println(p.toString());
    }

    Map<String, String> strMap = new HashMap<>();
    strMap.put("first", "Josh");
    strMap.put("last", "Juneau");
    System.out.println(strMap.values());
  }
}

class Player {

  private String firstName = null;
  private String lastName = null;
  private String position = null;
  private int status = -1;
  private int goals;

  public Player() {

  }

  public Player(String position, int status) {
    this.position = position;
    this.status = status;
  }

  public Player(String first, String last, int goals) {
    this.firstName = first;
    this.lastName = last;
    this.goals = goals;
  }

  public Player(String position, int status, String first, String last) {
    this.position = position;
    this.status = status;
    this.firstName = first;
    this.lastName = last;
  }

  public String playerString() {
    return getFirstName() + " " + getLastName() + " - " + getPosition();
  }

  /**
   * @return the firstName
   */
  public String getFirstName() {
    return firstName;
  }

  /**
   * @param firstName
   *          the firstName to set
   */
  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }

  /**
   * @return the lastName
   */
  public String getLastName() {
    return lastName;
  }

  /**
   * @param lastName
   *          the lastName to set
   */
  public void setLastName(String lastName) {
    this.lastName = lastName;
  }

  /**
   * @return the position
   */
  public String getPosition() {
    return position;
  }

  /**
   * @param position
   *          the position to set
   */
  public void setPosition(String position) {
    this.position = position;
  }

  /**
   * @return the status
   */
  public int getStatus() {
    return status;
  }

  /**
   * @param status
   *          the status to set
   */
  public void setStatus(int status) {
    this.status = status;
  }

  /**
   * @return the goals
   */
  public int getGoals() {
    return goals;
  }

  /**
   * @param goals
   *          the goals to set
   */
  public void setGoals(int goals) {
    this.goals = goals;
  }

}
Safely Enabling Types or Methods to Operate on Objects of Various Types - Java Object Oriented Design

Description

Demo Code

Result

Related Tutorials
