实验11泛型与集合

实验内容：
(1)定义一个泛型类In strume nt<E >，其中包括一个泛型方法void play(E x) 定义两种乐器类：Cello、Violin可以进行演奏。

定义一个测试类进行测试。

package ex111;
public class Violin {
public String toStri ng()
{
System.out.println("violin ....... ");
return "";
} }
package ex111;
public class Test_Ma in {
public static void main( Stri ng[] args) {
instrument<Cello>model = new instrument<Cello>(); in strume ntvVioli n>
model1 = new in strume ntvVioli n>(); Cello cello = new Cello();
Violin violin = new Violi n();
model.play(cello);
model1.play(violi n);
}
}
package ex111;
class in strume nt<E> {//泛型类void play(E x)
{
x.toStri ng();
} }
package ex111;
public class Cello {
public Stri ng toStri ng(){
System.out.println("cello ....... ");
return "";
}
}
(2)输入10个数字保存到List中，并按倒序显示出来
package ex112;
import java.util.ArrayList;
import java.util.Collectio ns;
import java.util.List;
import java.util.Sca nner; public class Test{
public static void main(final String[] args) {
final List< In teger> in tegers = new ArrayListvl nteger>();
final Scanner sca nner = new Scann er(System.i n);
for (int i = 1; i <= 3; i++) {
try {
System.out.pri ntl n("输入第"+ i + "个数吧");
final int in put = In teger.parse In t(sca nner.n ext());
in tegers.add(i nput);
}
catch (final Throwable e) {
System.err.pri ntln (”这不是个数字，我可是超级程序");
i--;
con ti nue;
}
}
//Collections.sort(integers);// 自然排
Collect ion s.reverse(i ntegers);// 倒排
for (final In teger in teger : in tegers) {
System.out.pri ntln (i nteger);
}
}
} System.out.pri ntln (i nteger);
}
}
}
package ex113;
import java.util.HashMap;
import java.util.Map;
public class Test {
public static void main( Stri ng[] args) {
Map<Stri ng,I nteger> map=new HashMap<Stri ng,l nteger>(); Sort
s=new Sort();
s.creatMap(map);
s.Sort(map);
}
}
(3)编写一个程序，把学生名和考试分数录入到Map中，并按分数显示前
三名学生的名字。

要求定义Stude nt类，封装学生名和考试分数2个属性及方法。

、TreeMap TreeSe；package ex113; import java.util.ArrayList;
import java.util.Collectio n;
import java.util.Collectio ns;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class Stude nt {
private String n ame; private int score; public Stude nt(){ }
public Stude nt(Stri ng n ame,i nt score) { this .n ame=n ame;
this.score=score;
}
public Stri ng getName() { return n ame;
}
public void setName(Stri ng n ame) { this. name = n ame;
}
public int getScore() {
return score;
}
public void setScore(i nt score) { this.score = score;
}
}
package ex113;
import java.util.ArrayList;
import java.util.Collectio n;
import java.util.Collectio ns;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Sca nner;
import java.util.Set;
public class Sort {
public void creatMap(Map<Stri ng,l nteger> map){
Scanner in put=new Scann er(System.i n);
System.out.println("请输入学生人数");
int nu mber =in put. nextl nt();
System.out.println(”请输入学生姓名和分数:");
for(int i=0;i<number;i++){
Stude nt stu=new Stude nt(i nput. next(),i nput .n extI nt());
map.put(stu.getName(),stu.getScore());
}
}
public void Sort(Map<Stri ng,I nteger> map){
Collecti onvln teger> score = map.values();
Set< In teger> set=new HashSetv In teger>();
for(I nteger s:score)
set.add(s);
List< In teger>list=new ArrayList(set);
Collectio ns.sort(list);
Collectio ns.reverse(list);
Set<Stri ng> n ame = map.keySet();
System.out.pri ntln("前三名学生的姓名是："); int m=0;
for(I nteger i:list){
m++;
if(m<=3){
for(Stri ng s:n ame)
{
if(i==map.get(s))
System.out.println(”第"+m+"名:"+s);
}
}
}
}。