李清华201772020113《面向对象程序设计（java）》第十一周学习总结

实验十一   集合

实验时间 2018-11-8

1、实验目的与要求

(1) 掌握Vetor、Stack、Hashtable三个类的用途及常用API；

(2) 了解java集合框架体系组成；

(3) 掌握ArrayList、LinkList两个类的用途及常用API。

(4) 了解HashSet类、TreeSet类的用途及常用API。

(5)了解HashMap、TreeMap两个类的用途及常用API；

(6) 结对编程（Pair programming）练习，体验程序开发中的两人合作。

2、实验内容和步骤

实验1： 导入第9章示例程序，测试程序并进行代码注释。

测试程序1：

l  使用JDK命令运行编辑、运行以下三个示例程序，结合运行结果理解程序；

掌握Vetor、Stack、Hashtable三个类的用途及常用API。

//示例程序1

import java.util.Vector;

class Cat {

private int catNumber;

Cat(int i) {

catNumber = i;

}

void print() {

System.out.println("Cat #" + catNumber);

}

}

class Dog {

private int dogNumber;

Dog(int i) {

dogNumber = i;

}

void print() {

System.out.println("Dog #" + dogNumber);

}

}

public class CatsAndDogs {

public static void main(String[] args) {

Vector cats = new Vector();

for (int i = 0; i < 7; i++)

cats.addElement(new Cat(i));

cats.addElement(new Dog(7));

for (int i = 0; i < cats.size(); i++)

((Cat) cats.elementAt(i)).print();

}

}

//示例程序2

import java.util.*;

public class Stacks {

static String[] months = { "1", "2", "3", "4" };

public static void main(String[] args) {

Stack stk = new Stack();

for (int i = 0; i < months.length; i++)

stk.push(months[i]);

System.out.println(stk);

System.out.println("element 2=" + stk.elementAt(2));

while (!stk.empty())

System.out.println(stk.pop());

}

}

//示例程序3

import java.util.*;

class Counter {

int i = 1;

public String toString() {

return Integer.toString(i);

}

}

public class Statistics {

public static void main(String[] args) {

Hashtable ht = new Hashtable();

for (int i = 0; i < 10000; i++) {

Integer r = new Integer((int) (Math.random() * 20));

if (ht.containsKey(r))

((Counter) ht.get(r)).i++;

else

ht.put(r, new Counter());

}

System.out.println(ht);

}

}

实验结果1

实验结果2

实验结果3

测试程序2：

使用JDK命令编辑运行ArrayListDemo和LinkedListDemo两个程序，结合程序运行结果理解程序；

import java.util.*;

public class ArrayListDemo {

public static void main(String[] argv) {

ArrayList al = new ArrayList();

// Add lots of elements to the ArrayList...

al.add(new Integer(11));

al.add(new Integer(12));

al.add(new Integer(13));

al.add(new String("hello"));

// First print them out using a for loop.

System.out.println("Retrieving by index:");

for (int i = 0; i < al.size(); i++) {

System.out.println("Element " + i + " = " + al.get(i));

}

}

}

import java.util.*;

public class LinkedListDemo {

    public static void main(String[] argv) {

        LinkedList l = new LinkedList();

        l.add(new Object());

        l.add("Hello");

        l.add("zhangsan");

        ListIterator li = l.listIterator(0);

        while (li.hasNext())

            System.out.println(li.next());

        if (l.indexOf("Hello") < 0)  

            System.err.println("Lookup does not work");

        else

            System.err.println("Lookup works");

   }

}

l  在Elipse环境下编辑运行调试教材360页程序9-1，结合程序运行结果理解程序；

l  掌握ArrayList、LinkList两个类的用途及常用API。

package linkedList;

import java.util.*;

/**
 * This program demonstrates operations on linked lists.
 * @version 1.11 2012-01-26
 * @author Cay Horstmann
 */
public class LinkedListTest
{
   public static void main(String[] args)
   {
      List<String> a = new LinkedList<>();
      a.add("Amy");
      a.add("Carl");
      a.add("Erica");

      List<String> b = new LinkedList<>();
      b.add("Bob");
      b.add("Doug");
      b.add("Frances");
      b.add("Gloria");

      // merge the words from b into a

      ListIterator<String> aIter = a.listIterator();
      Iterator<String> bIter = b.iterator();

      while (bIter.hasNext())
      {
         if (aIter.hasNext()) aIter.next();
         aIter.add(bIter.next());
      }

      System.out.println(a);

      // remove every second word from b

      bIter = b.iterator();
      while (bIter.hasNext())
      {
         bIter.next(); // skip one element
         if (bIter.hasNext())
         {
            bIter.next(); // skip next element
            bIter.remove(); // remove that element
         }
      }

      System.out.println(b);

      // bulk operation: remove all words in b from a

      a.removeAll(b);

      System.out.println(a);
   }
}

测试程序3：

l  运行SetDemo程序，结合运行结果理解程序；

import java.util.*;

public class SetDemo {

    public static void main(String[] argv) {

        HashSet h = new HashSet(); //也可以 Set h=new HashSet()

        h.add("One");

        h.add("Two");

        h.add("One"); // DUPLICATE

        h.add("Three");

        Iterator it = h.iterator();

        while (it.hasNext()) {

             System.out.println(it.next());

        }

    }

}

l  在Elipse环境下调试教材365页程序9-2，结合运行结果理解程序；了解HashSet类的用途及常用API。

 package set;

 import java.util.*;

 /**
  * This program uses a set to print all unique words in System.in.
  * @version 1.12 2015-06-21
  * @author Cay Horstmann
  */
 public class SetTest
 {
    public static void main(String[] args)
    {
       Set<String> words = new HashSet<>(); // HashSet implements Set
       long totalTime = 0;

       try (Scanner in = new Scanner(System.in))
       {
          while (in.hasNext())
          {
             String word = in.next();
             long callTime = System.currentTimeMillis();
             words.add(word);
             callTime = System.currentTimeMillis() - callTime;
             totalTime += callTime;
          }
       }

       Iterator<String> iter = words.iterator();
       for (int i = 1; i <= 20 && iter.hasNext(); i++)
          System.out.println(iter.next());
       System.out.println(". . .");
       System.out.println(words.size() + " distinct words. " + totalTime + " milliseconds.");
    }
 }

l  在Elipse环境下调试教材367页-368程序9-3、9-4，结合程序运行结果理解程序；了解TreeSet类的用途及常用API。

 package treeSet;

 import java.util.*;

 /**
  * An item with a description and a part number.
  */
 public class Item implements Comparable<Item>
 {
    private String description;
    private int partNumber;

    /**
     * Constructs an item.
     *
     * @param aDescription
     *           the item's description
     * @param aPartNumber
     *           the item's part number
     */
    public Item(String aDescription, int aPartNumber)
    {
       description = aDescription;
       partNumber = aPartNumber;
    }

    /**
     * Gets the description of this item.
     *
     * @return the description
     */
    public String getDescription()
    {
       return description;
    }

    public String toString()
    {
       return "[description=" + description + ", partNumber=" + partNumber + "]";
    }

    public boolean equals(Object otherObject)
    {
       if (this == otherObject) return true;
       if (otherObject == null) return false;
       if (getClass() != otherObject.getClass()) return false;
       Item other = (Item) otherObject;
       return Objects.equals(description, other.description) && partNumber == other.partNumber;
    }

    public int hashCode()
    {
       return Objects.hash(description, partNumber);
    }

    public int compareTo(Item other)
    {
       int diff = Integer.compare(partNumber, other.partNumber);
       return diff != 0 ? diff : description.compareTo(other.description);
    }
 }

 package treeSet;

 import java.util.*;

 /**
  * This program sorts a set of item by comparing their descriptions.
  * @version 1.12 2015-06-21
  * @author Cay Horstmann
  */
 public class TreeSetTest
 {
    public static void main(String[] args)
    {
       SortedSet<Item> parts = new TreeSet<>();
       parts.add(new Item("Toaster", 1234));
       parts.add(new Item("Widget", 4562));
       parts.add(new Item("Modem", 9912));
       System.out.println(parts);

       NavigableSet<Item> sortByDescription = new TreeSet<>(
             Comparator.comparing(Item::getDescription));

       sortByDescription.addAll(parts);
       System.out.println(sortByDescription);
    }
 }

测试程序4：

使用JDK命令运行HashMapDemo程序，结合程序运行结果理解程序；

import java.util.*;

public class HashMapDemo {

   public static void main(String[] argv) {

      HashMap h = new HashMap();

      // The hash maps from company name to address.

      h.put("Adobe", "Mountain View, CA");

      h.put("IBM", "White Plains, NY");

      h.put("Sun", "Mountain View, CA");

      String queryString = "Adobe";

      String resultString = (String)h.get(queryString);

      System.out.println("They are located in: " +  resultString);

  }

}

实验结果：

l  在Elipse环境下调试教材373页程序9-6，结合程序运行结果理解程序；

l  了解HashMap、TreeMap两个类的用途及常用API。

 package map;

 import java.util.*;

 /**
  * This program demonstrates the use of a map with key type String and value type Employee.
  * @version 1.12 2015-06-21
  * @author Cay Horstmann
  */
 public class MapTest
 {
    public static void main(String[] args)
    {
       Map<String, Employee> staff = new HashMap<>();
       staff.put("144-25-5464", new Employee("Amy Lee"));
       staff.put("567-24-2546", new Employee("Harry Hacker"));
       staff.put("157-62-7935", new Employee("Gary Cooper"));
       staff.put("456-62-5527", new Employee("Francesca Cruz"));

       // print all entries

       System.out.println(staff);

       // remove an entry

       staff.remove("567-24-2546");

       // replace an entry

       staff.put("456-62-5527", new Employee("Francesca Miller"));

       // look up a value

       System.out.println(staff.get("157-62-7935"));

       // iterate through all entries

       staff.forEach((k, v) ->
          System.out.println("key=" + k + ", value=" + v));
    }
 }

 package map;

 /**
  * A minimalist employee class for testing purposes.
  */
 public class Employee
 {
    private String name;
    private double salary;

    /**
     * Constructs an employee with $0 salary.
     * @param n the employee name
     */
    public Employee(String name)
    {
       this.name = name;
       salary = 0;
    }

    public String toString()
    {
       return "[name=" + name + ", salary=" + salary + "]";
    }
 }

实验结果：

实验2：结对编程练习：

l  关于结对编程：以下图片是一个结对编程场景：两位学习伙伴坐在一起，面对着同一台显示器，使用着同一键盘，同一个鼠标，他们一起思考问题，一起分析问题，一起编写程序。

l  关于结对编程的阐述可参见以下链接：

http://www.cnblogs.com/xinz/archive/2011/08/07/2130332.html

http://en.wikipedia.org/wiki/Pair_programming

l  对于结对编程中代码设计规范的要求参考：

http://www.cnblogs.com/xinz/archive/2011/11/20/2255971.html

以下实验，就让我们来体验一下结对编程的魅力。

l  确定本次实验结对编程合作伙伴；

l  各自运行合作伙伴实验九编程练习1，结合使用体验对所运行程序提出完善建议；

 package test1;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Scanner;

 public class Main{
     private static ArrayList<Student> studentlist;
     public static void main(String[] args) {
         studentlist = new ArrayList<>();
         Scanner scanner = new Scanner(System.in);
         File file = new File("F:\\身份证号.txt");
         try {
             FileInputStream fis = new FileInputStream(file);
             BufferedReader in = new BufferedReader(new InputStreamReader(fis));
             String temp = null;
             while ((temp = in.readLine()) != null) {

                 Scanner linescanner = new Scanner(temp);

                 linescanner.useDelimiter(" ");
                 String name = linescanner.next();
                 String number = linescanner.next();
                 String sex = linescanner.next();
                 String age = linescanner.next();
                 String province =linescanner.nextLine();
                 Student student = new Student();
                 student.setName(name);
                 student.setnumber(number);
                 student.setsex(sex);
                 int a = Integer.parseInt(age);
                 student.setage(a);
                 student.setprovince(province);
                 studentlist.add(student);

             }
         } catch (FileNotFoundException e) {
             System.out.println("学生信息文件找不到");
             e.printStackTrace();
         } catch (IOException e) {
             System.out.println("学生信息文件读取错误");
             e.printStackTrace();
         }
         boolean isTrue = true;
         while (isTrue) {
             System.out.println("选择你的操作，输入正确格式的选项");
             System.out.println("A.按姓名字典排序");
             System.out.println("B.输出年龄最大和年龄最小的人");
             System.out.println("C.寻找老乡");
             System.out.println("D.寻找年龄相近的人");
             System.out.println("F.退出");
             String m = scanner.next();
             switch (m) {
             case "A":
                 Collections.sort(studentlist);
                 System.out.println(studentlist.toString());
                 break;
             case "B":
                  int max=0,min=100;
                  int j,k1 = 0,k2=0;
                  for(int i=1;i<studentlist.size();i++)
                  {
                      j=studentlist.get(i).getage();
                  if(j>max)
                  {
                      max=j;
                      k1=i;
                  }
                  if(j<min)
                  {
                    min=j;
                    k2=i;
                  }

                  }
                  System.out.println("年龄最大："+studentlist.get(k1));
                  System.out.println("年龄最小："+studentlist.get(k2));
                 break;
             case "C":
                  System.out.println("老家?");
                  String find = scanner.next();
                  String place=find.substring(0,3);
                  for (int i = 0; i <studentlist.size(); i++)
                  {
                      if(studentlist.get(i).getprovince().substring(1,4).equals(place))
                          System.out.println("老乡"+studentlist.get(i));
                  }
                  break;

             case "D":
                 System.out.println("年龄：");
                 int yourage = scanner.nextInt();
                 int near=agenear(yourage);
                 int value=yourage-studentlist.get(near).getage();
                 System.out.println(""+studentlist.get(near));
                 break;
             case "F":
                 isTrue = false;
                 System.out.println("退出程序!");
                 break;
                 default:
                 System.out.println("输入有误");

             }
         }
     }
         public static int agenear(int age) {
         int j=0,min=53,value=0,k=0;
          for (int i = 0; i < studentlist.size(); i++)
          {
              value=studentlist.get(i).getage()-age;
              if(value<0) value=-value;
              if (value<min)
              {
                 min=value;
                 k=i;
              }
           }
          return k;
       }

 }

 package test1;

 public class Student implements Comparable<Student> {

     private String name;
     private String number ;
     private String sex ;
     private int age;
     private String province;

     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getnumber() {
         return number;
     }
     public void setnumber(String number) {
         this.number = number;
     }
     public String getsex() {
         return sex ;
     }
     public void setsex(String sex ) {
         this.sex =sex ;
     }
     public int getage() {

         return age;
         }
         public void setage(int age) {
             // int a = Integer.parseInt(age);
         this.age= age;
         }

     public String getprovince() {
         return province;
     }
     public void setprovince(String province) {
         this.province=province ;
     }

     public int compareTo(Student o) {
        return this.name.compareTo(o.getName());
     }

     public String toString() {
         return  name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n";
     }
 }

完善建议：无

l  各自运行合作伙伴实验十编程练习2，结合使用体验对所运行程序提出完善建议；

 package shiyan;
 import java.util.Scanner;
 import java.io.FileNotFoundException;
 import java.io.PrintWriter;

 public class Main {
     public static void main(String[] args) {
         Scanner in=new Scanner(System.in);
         PrintWriter output = null;
         try {
             output = new PrintWriter("E:/test.txt");
         } catch (FileNotFoundException e) {
             // TODO 自动生成的 catch 块
             System.out.println("文件输出失败");
             e.printStackTrace();
         }
         int sum=0;
         jisuanji js=new jisuanji();
         for (int i = 0; i < 10; i++) {
             int a = (int) Math.round(Math.random() * 100);
             int b = (int) Math.round(Math.random() * 100);
             int n = (int) Math.round(Math.random() * 4 );

             switch(n)
                {
                case 1:
                    System.out.println(a+"/"+b+"=");
                    while(b==0){
                        b = (int) Math.round(Math.random() * 100);
                        }
                    while(a%b!=0) {
                        a = (int) Math.round(Math.random() * 100);
                        b = (int) Math.round(Math.random() * 100);
                    }
                    double c = in.nextDouble();
                    output.println(a+"/"+b+"="+c);
                    if (c == js.chu(a,b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }

                    break;

                case 2:
                    System.out.println(a+"*"+b+"=");
                    int c1 = in.nextInt();
                    output.println(a+"*"+b+"="+c1);
                    if (c1 == js.chen(a, b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }
                    break;
                case 3:
                    System.out.println(a+"+"+b+"=");
                    int c2 = in.nextInt();
                    output.println(a+"+"+b+"="+c2);
                    if (c2 == js.jia(a, b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }

                    break ;
                case 4:
                    System.out.println(a+"-"+b+"=");
                    while(a<b) {
                        a = (int) Math.round(Math.random() * 100);
                        b = (int) Math.round(Math.random() * 100);
                    }
                    int c3 = in.nextInt();
                    output.println(a+"-"+b+"="+c3);
                    if (c3 == js.jian(a,b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }
                    break ;

                    } 

               }
             System.out.println("成绩"+sum);
             output.println("成绩:"+sum);
             output.close();
         }
     }

 package shiyan;

 public class jisuanji<T> {
     private T a;
     private T b;
     public jisuanji() {
         a=null;
         b=null;
     }
     public jisuanji(T a,T b) {
         this.a=a;
         this.b=b;
     }
     public int jia(int a,int b)
     {
         return a+b;
     }
     public int jian(int a,int b)
     {
         return a-b;
     }
     public int chen(int a,int b)
     {
         return a*b;
     }
     public int chu(int a,int b)
     {
         if(b!=0&&a%b==0)
             return a/b;
         else
             return 0;
     }
 }

完善建议：jisuanji类的除法的一些限制条件多余，可以不写，简化代码。

l  采用结对编程方式，与学习伙伴合作完成实验九编程练习1；

 package test1;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Scanner;

 public class Main{
     private static ArrayList<Student> studentlist;
     public static void main(String[] args) {
         studentlist = new ArrayList<>();
         Scanner scanner = new Scanner(System.in);
         File file = new File("F:\\身份证号.txt");
         try {
             FileInputStream fis = new FileInputStream(file);
             BufferedReader in = new BufferedReader(new InputStreamReader(fis));
             String temp = null;
             while ((temp = in.readLine()) != null) {

                 Scanner linescanner = new Scanner(temp);

                 linescanner.useDelimiter(" ");
                 String name = linescanner.next();
                 String number = linescanner.next();
                 String sex = linescanner.next();
                 String age = linescanner.next();
                 String province =linescanner.nextLine();
                 Student student = new Student();
                 student.setName(name);
                 student.setnumber(number);
                 student.setsex(sex);
                 int a = Integer.parseInt(age);
                 student.setage(a);
                 student.setprovince(province);
                 studentlist.add(student);

             }
         } catch (FileNotFoundException e) {
             System.out.println("学生信息文件找不到");
             e.printStackTrace();
         } catch (IOException e) {
             System.out.println("学生信息文件读取错误");
             e.printStackTrace();
         }
         boolean isTrue = true;
         while (isTrue) {
             System.out.println("选择你的操作，输入正确格式的选项");
             System.out.println("A.按姓名字典排序");
             System.out.println("B.输出年龄最大和年龄最小的人");
             System.out.println("C.寻找老乡");
             System.out.println("D.寻找年龄相近的人");
             System.out.println("F.退出");
             String m = scanner.next();
             switch (m) {
             case "A":
                 Collections.sort(studentlist);
                 System.out.println(studentlist.toString());
                 break;
             case "B":
                  int max=0,min=100;
                  int j,k1 = 0,k2=0;
                  for(int i=1;i<studentlist.size();i++)
                  {
                      j=studentlist.get(i).getage();
                  if(j>max)
                  {
                      max=j;
                      k1=i;
                  }
                  if(j<min)
                  {
                    min=j;
                    k2=i;
                  }

                  }
                  System.out.println("年龄最大："+studentlist.get(k1));
                  System.out.println("年龄最小："+studentlist.get(k2));
                 break;
             case "C":
                  System.out.println("老家?");
                  String find = scanner.next();
                  String place=find.substring(0,3);
                  for (int i = 0; i <studentlist.size(); i++)
                  {
                      if(studentlist.get(i).getprovince().substring(1,4).equals(place))
                          System.out.println("老乡"+studentlist.get(i));
                  }
                  break;

             case "D":
                 System.out.println("年龄：");
                 int yourage = scanner.nextInt();
                 int near=agenear(yourage);
                 int value=yourage-studentlist.get(near).getage();
                 System.out.println(""+studentlist.get(near));
                 break;
             case "F":
                 isTrue = false;
                 System.out.println("退出程序!");
                 break;
                 default:
                 System.out.println("输入有误");

             }
         }
     }
         public static int agenear(int age) {
         int j=0,min=53,value=0,k=0;
          for (int i = 0; i < studentlist.size(); i++)
          {
              value=studentlist.get(i).getage()-age;
              if(value<0) value=-value;
              if (value<min)
              {
                 min=value;
                 k=i;
              }
           }
          return k;
       }

 }

 package test1;

 public class Student implements Comparable<Student> {

     private String name;
     private String number ;
     private String sex ;
     private int age;
     private String province;

     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getnumber() {
         return number;
     }
     public void setnumber(String number) {
         this.number = number;
     }
     public String getsex() {
         return sex ;
     }
     public void setsex(String sex ) {
         this.sex =sex ;
     }
     public int getage() {

         return age;
         }
         public void setage(int age) {
             // int a = Integer.parseInt(age);
         this.age= age;
         }

     public String getprovince() {
         return province;
     }
     public void setprovince(String province) {
         this.province=province ;
     }

     public int compareTo(Student o) {
        return this.name.compareTo(o.getName());
     }

     public String toString() {
         return  name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n";
     }
 }

l  采用结对编程方式，与学习伙伴合作完成实验十编程练习2。

 package shiyan;
 import java.util.Scanner;
 import java.io.FileNotFoundException;
 import java.io.PrintWriter;

 public class Main {
     public static void main(String[] args) {
         Scanner in=new Scanner(System.in);
         PrintWriter output = null;
         try {
             output = new PrintWriter("E:/test.txt");
         } catch (FileNotFoundException e) {
             // TODO 自动生成的 catch 块
             System.out.println("文件输出失败");
             e.printStackTrace();
         }
         int sum=0;
         jisuanji js=new jisuanji();
         for (int i = 0; i < 10; i++) {
             int a = (int) Math.round(Math.random() * 100);
             int b = (int) Math.round(Math.random() * 100);
             int n = (int) Math.round(Math.random() * 4 );

             switch(n)
                {
                case 1:
                    System.out.println(a+"/"+b+"=");
                    while(b==0){
                        b = (int) Math.round(Math.random() * 100);
                        }
                    while(a%b!=0) {
                        a = (int) Math.round(Math.random() * 100);
                        b = (int) Math.round(Math.random() * 100);
                    }
                    double c = in.nextDouble();
                    output.println(a+"/"+b+"="+c);
                    if (c == js.chu(a,b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }

                    break;

                case 2:
                    System.out.println(a+"*"+b+"=");
                    int c1 = in.nextInt();
                    output.println(a+"*"+b+"="+c1);
                    if (c1 == js.chen(a, b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }
                    break;
                case 3:
                    System.out.println(a+"+"+b+"=");
                    int c2 = in.nextInt();
                    output.println(a+"+"+b+"="+c2);
                    if (c2 == js.jia(a, b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }

                    break ;
                case 4:
                    System.out.println(a+"-"+b+"=");
                    while(a<b) {
                        a = (int) Math.round(Math.random() * 100);
                        b = (int) Math.round(Math.random() * 100);
                    }
                    int c3 = in.nextInt();
                    output.println(a+"-"+b+"="+c3);
                    if (c3 == js.jian(a,b)) {
                        sum += 10;
                        System.out.println("答案正确");
                    }
                    else {
                        System.out.println("答案错误");
                    }
                    break ;

                    } 

               }
             System.out.println("成绩"+sum);
             output.println("成绩:"+sum);
             output.close();
         }
     }

 package shiyan;

 public class jisuanji<T> {
     private T a;
     private T b;
     public jisuanji() {
         a=null;
         b=null;
     }
     public jisuanji(T a,T b) {
         this.a=a;
         this.b=b;
     }
     public int jia(int a,int b)
     {
         return a+b;
     }
     public int jian(int a,int b)
     {
         return a-b;
     }
     public int chen(int a,int b)
     {
         return a*b;
     }
     public int chu(int a,int b)
     {
         if(b!=0&&a%b==0)
             return a/b;
         else
             return 0;
     }
 }

本周实验总结：

学会了一些简单的数据结构，例如链，栈，队列，散列表等。还有Java的集合框架，集合类的内容。

复习了前面学过的知识细节，例如强制转换类型时进行判断的instanceof语句。初步体会了合作编程，互相提高的过程和乐趣。