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Java 安全地使类型或方法能够对各种类型的对象进行操作

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安全地使类型或方法能够对各种类型的对象进行操作

实例源码：

源代码：

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/* 
 来自 
*时代Java - N o w  J a v a . c o m*/

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);

team.add(player2);

team.add(player3);

team.add(player4);

team.add(player5);

List objectList = new ArrayList();/* 来自 nowjava.com*/

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) {
/**代码未完, 请加载全部代码(NowJava.com).**/

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编辑于 2020-03-26 09:23:272020-03-26 09:23:27

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