问题:
利用Map，完成下面的功能：
从命令行读入一个字符串，表示一个年份，输出该年的世界杯冠军是哪支球队。如果该 年没有举办世界杯，则输
出：没有举办世界杯。
附：世界杯冠军以及对应的夺冠年份，请参考本章附录。 附录
历届世界杯冠军 .
（Map）在原有世界杯Map 的基础上，增加如下功能： 读入一支球队的名字，输出该球队夺冠的年份列表。
例如，读入“巴西”，应当输出 1958 1962 1970 1994 2002 读入“荷兰”，应当输出 没有获得过世界杯.
代码如下:
首先创建一个实体类用于存放球队的信息:
package practice.resolution3;
public class Champion {
private int num;
private int year;
private String place;
private String country;
public Champion() {
// TODO Auto-generated constructor stub
}
public Champion(int num, int year, String place, String country) {
super();
this.num = num;
this.year = year;
this.place = place;
this.country = country;
}
public int getNum() {
return num;
}
public void setNum(int num) {
this.num = num;
}
public int getYear() {
return year;
}
public void setYear(int year) {
this.year = year;
}
public String getPlace() {
return place;
}
public void setPlace(String place) {
this.place = place;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
@Override
public String toString() {
return "Champion [num=" + num + ", year=" + year + ", place=" + place + ", country=" + country + "]";
}
}
测试类包含球队数据和执行方法:
package practice.resolution3;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Scanner;
public class TestChampion {
private Map<Integer,Champion> cmap;
{
cmap = new HashMap<Integer,Champion>();
cmap.put(1930,new Champion(1,1930,"乌拉圭","乌拉圭"));
cmap.put(1934,new Champion(2,1934,"意大利","意大利"));
cmap.put(1938,new Champion(3,1938,"法国","意大利"));
cmap.put(1950,new Champion(4,1950,"巴西","乌拉圭"));
cmap.put(1954,new Champion(5,1954,"瑞士","西德"));
cmap.put(1958,new Champion(6,1958,"瑞典","巴西"));
cmap.put(1962,new Champion(7,1962,"智利","巴西"));
cmap.put(1966,new Champion(8,1966,"英格兰","英格兰"));
cmap.put(1970,new Champion(9,1970,"墨西哥","巴西"));
cmap.put(1974,new Champion(10,1974,"前西德","西德"));
cmap.put(1978,new Champion(11,1978,"阿根廷","阿根廷"));
cmap.put(1982,new Champion(12,1982,"西班牙","意大利"));
cmap.put(1986,new Champion(13,1986,"墨西哥","阿根廷"));
cmap.put(1990,new Champion(14,1990,"意大利","西德"));
cmap.put(1994,new Champion(15,1994,"美国","巴西"));
cmap.put(1998,new Champion(16,1998,"法国","法国"));
cmap.put(2002,new Champion(17,2002,"韩日","巴西"));
cmap.put(2006,new Champion(18,2006,"德国","意大利"));
cmap.put(2010,new Champion(19,2010,"南非","西班牙"));
cmap.put(2014,new Champion(20,2014,"巴西","德国"));
}
public void showChampion() {
System.out.println("请输入年份：");
Scanner sc = new Scanner(System.in);
String s = sc.nextLine();
if(s.matches("^\\d{4}$")) {
int year = Integer.parseInt(s);
Champion v = cmap.get(year);
if(v == null) {
System.out.println(year+"年未举办世界杯");
}else {
System.out.println("冠军队伍"+v);
}
} else {
System.out.println("输入年份有误，请重新输入");
}
showChampion();
}
public void showYear() {
System.out.println("请输入获奖队伍名称:");
Scanner sc = new Scanner(System.in);
String team = sc.nextLine();
//获取所有值的集合
Collection<Champion> c = cmap.values();
//将Collection转换为ArrayList
List<Champion> list = new ArrayList<>(c);
//统计获奖次数
int count = 0;
for(Champion ch:list) {
if(Objects.equals(team, ch.getCountry())) {
System.out.println(team+"获得冠军的年份:"+ch.getYear());
count++;
}
}
if(count == 0) {
System.out.println("该队伍没有获得冠军,再接再厉");
}else {
showYear();
}
}
public static void main(String[] args) {
TestChampion tc= new TestChampion();
// tc.showChampion();
tc.showYear();
}
}
测试结果:
本题涉及到集合框架中List集合和Map集合的运用,希望大家能从此题中学到一些集合中的知识.