实验11泛型与集合

实验内容：

(1)定义一个泛型类In strume nt，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) {

instrumentmodel = new instrument(); 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 {//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 map=new HashMap(); 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 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

Stude nt stu=new Stude nt(i nput. next(),i nput .n extI nt());

map.put(stu.getName(),stu.getScore());

}

}

public void Sort(Map 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);