201771010101 白玛次仁《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；
l 掌握Vetor、Stack、Hashtable三个类的用途及常用API。
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//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(); } } |
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//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()); } } |
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//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); } } |
示例程序1
package demo; 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 < 7; i++) ((Cat) cats.elementAt(i)).print(); ((Dog) cats.elementAt(7)).print(); } }
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()); } }
package demo;
import java.util.*;
class Counter {
int i = 1;
//default：
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));
//用Math.random()
if (ht.containsKey(r))
((Counter) ht.get(r)).i++;
else
ht.put(r, new Counter());
//输出r中数据的键值对出现的次数
}
System.out.println(ht);
}
}
测试程序2
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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)); } } } |
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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"); } } |
import java.util.*;
public class ArrayListDemo//ArrayList使用了数组的实现
{
public static void main(String[] argv) {
ArrayList al = new ArrayList();
//在ArrayList中添加大量元素
al.add(new Integer(11));
al.add(new Integer(12));
al.add(new Integer(13));
al.add(new String("hello"));//下标从0开始，添加4个元素
// 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));
}
}
}
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。
Arraylist:
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：
l 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); } } |
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;
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));
}
}
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；
穷吉
import java.io;
2 import java.io.File;
3 import java.io.FileInputStream;
4 import java.io.FileNotFoundException;
5 import java.io.IOException;
6 import java.io.InputStreamReader;
7 import java.util.ArrayList;
8 import java.util.Arrays;
9 import java.util.Collections;
10 import java.util.Scanner;
11
12 public class Test{
13 private static ArrayList<Student> studentlist;
14 public static void main(String[] args) {
15 studentlist = new ArrayList<>();
16 Scanner scanner = new Scanner(System.in);
17 File file = new File("C:\\下载\\身份证号.txt");
18 try {
19 FileInputStream fis = new FileInputStream(file);
20 BufferedReader in = new BufferedReader(new InputStreamReader(fis));
21 String temp = null;
22 while ((temp = in.readLine()) != null) {
23
24 Scanner linescanner = new Scanner(temp);
25
26 linescanner.useDelimiter(" ");
27 String name = linescanner.next();
28 String number = linescanner.next();
29 String sex = linescanner.next();
30 String age = linescanner.next();
31 String province =linescanner.nextLine();
32 Student student = new Student();
33 student.setName(name);
34 student.setnumber(number);
35 student.setsex(sex);
36 int a = Integer.parseInt(age);
37 student.setage(a);
38 student.setprovince(province);
39 studentlist.add(student);
40
41 }
42 } catch (FileNotFoundException e) {
43 System.out.println("学生信息文件找不到");
44 e.printStackTrace();
45 } catch (IOException e) {
46 System.out.println("学生信息文件读取错误");
47 e.printStackTrace();
48 }
49 boolean isTrue = true;
50 while (isTrue) {
51 System.out.println("选择你的操作，输入正确格式的选项");
52 System.out.println("1.按姓名字典序输出人员信息");
53 System.out.println("2.输出年龄最大和年龄最小的人");
54 System.out.println("3.查找老乡");
55 System.out.println("4.查找年龄相近的人");
56 System.out.println("5.退出");
57 String m = scanner.next();
58 switch (m) {
59 case "1":
60 Collections.sort(studentlist);
61 System.out.println(studentlist.toString());
62 break;
63 case "2":
64 int max=0,min=100;
65 int j,k1 = 0,k2=0;
66 for(int i=1;i<studentlist.size();i++)
67 {
68 j=studentlist.get(i).getage();
69 if(j>max)
70 {
71 max=j;
72 k1=i;
73 }
74 if(j<min)
75 {
76 min=j;
77 k2=i;
78 }
79
80 }
81 System.out.println("年龄最大："+studentlist.get(k1));
82 System.out.println("年龄最小："+studentlist.get(k2));
83 break;
84 case "3":
85 System.out.println("输入省份");
86 String find = scanner.next();
87 String place=find.substring(0,3);
88 for (int i = 0; i <studentlist.size(); i++)
89 {
90 if(studentlist.get(i).getprovince().substring(1,4).equals(place))
91 System.out.println("老乡"+studentlist.get(i));
92 }
93 break;
94
95 case "4":
96 System.out.println("年龄：");
97 int yourage = scanner.nextInt();
98 int near=agenear(yourage);
99 int value=yourage-studentlist.get(near).getage();
100 System.out.println(""+studentlist.get(near));
101 break;
102 case "5":
103 isTrue = false;
104 System.out.println("退出程序!");
105 break;
106 default:
107 System.out.println("输入有误");
108
109 }
110 }
111 }
112 public static int agenear(int age) {
113 int j=0,min=53,value=0,k=0;
114 for (int i = 0; i < studentlist.size(); i++)
115 {
116 value=studentlist.get(i).getage()-age;
117 if(value<0) value=-value;
118 if (value<min)
119 {
120 min=value;
121 k=i;
122 }
123 }
124 return k;
125 }
126
127 }
public class Student implements Comparable<Student> {
2
3 private String name;
4 private String number ;
5 private String sex ;
6 private int age;
7 private String province;
8
9 public String getName() {
10 return name;
11 }
12 public void setName(String name) {
13 this.name = name;
14 }
15 public String getnumber() {
16 return number;
17 }
18 public void setnumber(String number) {
19 this.number = number;
20 }
21 public String getsex() {
22 return sex ;
23 }
24 public void setsex(String sex ) {
25 this.sex =sex ;
26 }
27 public int getage() {
28
29 return age;
30 }
31 public void setage(int age) {
32 // int a = Integer.parseInt(age);
33 this.age= age;
34 }
35
36 public String getprovince() {
37 return province;
38 }
39 public void setprovince(String province) {
40 this.province=province ;
41 }
42
43 public int compareTo(Student o) {
44 return this.name.compareTo(o.getName());
45 }
46
47 public String toString() {
48 return name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n";
49 }
50 }
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；
穷吉
package 运算;
import java.util.Scanner;
public class Demo {
public static void main(String[] args) {
// 用户的答案要从键盘输入，因此需要一个键盘输入流
@SuppressWarnings("resource")
Scanner in = new Scanner(System.in);
// 定义一个变量用来统计得分
int sum = 0;
// 通过循环生成10道题
for (int i = 0; i < 10; i++) {
// 随机生成两个10以内的随机数作为被除数和除数
int a = (int) Math.round(Math.random() * 10);
int b = (int) Math.round(Math.random() * 10);
System.out.println(a + "/" + b + "=");
// 定义一个整数用来接收用户输入的答案
int c = in.nextInt();
// 判断用户输入的答案是否正确，正确给10分，错误不给分
if (c == a / b) {
sum += 10;
System.out.println("恭喜答案正确");
}
else {
System.out.println("抱歉，答案错误");
}
}
//输出用户的成绩
System.out.println("你的得分为"+sum);
}
}
package 运算;
public class Yuns {
public int add(int a,int b)
{
return a+b;
}
public int reduce(int a,int b)
{
if((a-b)>0)
return a-b;
else return 0;
}
public int multiply(int a,int b)
{
return a*b;
}
public int devision(int a,int b)
{
if(b!=0)
return a/b;
else return 0;
}
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；
import java.io;
2 import java.io.File;
3 import java.io.FileInputStream;
4 import java.io.FileNotFoundException;
5 import java.io.IOException;
6 import java.io.InputStreamReader;
7 import java.util.ArrayList;
8 import java.util.Arrays;
9 import java.util.Collections;
10 import java.util.Scanner;
11
12 public class Test{
13 private static ArrayList<Student> studentlist;
14 public static void main(String[] args) {
15 studentlist = new ArrayList<>();
16 Scanner scanner = new Scanner(System.in);
17 File file = new File("C:\\下载\\身份证号.txt");
18 try {
19 FileInputStream fis = new FileInputStream(file);
20 BufferedReader in = new BufferedReader(new InputStreamReader(fis));
21 String temp = null;
22 while ((temp = in.readLine()) != null) {
23
24 Scanner linescanner = new Scanner(temp);
25
26 linescanner.useDelimiter(" ");
27 String name = linescanner.next();
28 String number = linescanner.next();
29 String sex = linescanner.next();
30 String age = linescanner.next();
31 String province =linescanner.nextLine();
32 Student student = new Student();
33 student.setName(name);
34 student.setnumber(number);
35 student.setsex(sex);
36 int a = Integer.parseInt(age);
37 student.setage(a);
38 student.setprovince(province);
39 studentlist.add(student);
40
41 }
42 } catch (FileNotFoundException e) {
43 System.out.println("学生信息文件找不到");
44 e.printStackTrace();
45 } catch (IOException e) {
46 System.out.println("学生信息文件读取错误");
47 e.printStackTrace();
48 }
49 boolean isTrue = true;
50 while (isTrue) {
51 System.out.println("选择你的操作，输入正确格式的选项");
52 System.out.println("1.按姓名字典序输出人员信息");
53 System.out.println("2.输出年龄最大和年龄最小的人");
54 System.out.println("3.查找老乡");
55 System.out.println("4.查找年龄相近的人");
56 System.out.println("5.退出");
57 String m = scanner.next();
58 switch (m) {
59 case "1":
60 Collections.sort(studentlist);
61 System.out.println(studentlist.toString());
62 break;
63 case "2":
64 int max=0,min=100;
65 int j,k1 = 0,k2=0;
66 for(int i=1;i<studentlist.size();i++)
67 {
68 j=studentlist.get(i).getage();
69 if(j>max)
70 {
71 max=j;
72 k1=i;
73 }
74 if(j<min)
75 {
76 min=j;
77 k2=i;
78 }
79
80 }
81 System.out.println("年龄最大："+studentlist.get(k1));
82 System.out.println("年龄最小："+studentlist.get(k2));
83 break;
84 case "3":
85 System.out.println("输入省份");
86 String find = scanner.next();
87 String place=find.substring(0,3);
88 for (int i = 0; i <studentlist.size(); i++)
89 {
90 if(studentlist.get(i).getprovince().substring(1,4).equals(place))
91 System.out.println("老乡"+studentlist.get(i));
92 }
93 break;
94
95 case "4":
96 System.out.println("年龄：");
97 int yourage = scanner.nextInt();
98 int near=agenear(yourage);
99 int value=yourage-studentlist.get(near).getage();
100 System.out.println(""+studentlist.get(near));
101 break;
102 case "5":
103 isTrue = false;
104 System.out.println("退出程序!");
105 break;
106 default:
107 System.out.println("输入有误");
108
109 }
110 }
111 }
112 public static int agenear(int age) {
113 int j=0,min=53,value=0,k=0;
114 for (int i = 0; i < studentlist.size(); i++)
115 {
116 value=studentlist.get(i).getage()-age;
117 if(value<0) value=-value;
118 if (value<min)
119 {
120 min=value;
121 k=i;
122 }
123 }
124 return k;
125 }
126
127 }
public class Student implements Comparable<Student> {
2
3 private String name;
4 private String number ;
5 private String sex ;
6 private int age;
7 private String province;
8
9 public String getName() {
10 return name;
11 }
12 public void setName(String name) {
13 this.name = name;
14 }
15 public String getnumber() {
16 return number;
17 }
18 public void setnumber(String number) {
19 this.number = number;
20 }
21 public String getsex() {
22 return sex ;
23 }
24 public void setsex(String sex ) {
25 this.sex =sex ;
26 }
27 public int getage() {
28
29 return age;
30 }
31 public void setage(int age) {
32 // int a = Integer.parseInt(age);
33 this.age= age;
34 }
35
36 public String getprovince() {
37 return province;
38 }
39 public void setprovince(String province) {
40 this.province=province ;
41 }
42
43 public int compareTo(Student o) {
44 return this.name.compareTo(o.getName());
45 }
46
47 public String toString() {
48 return name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n";
49 }
50 }
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 运算;
import java.util.Scanner;
public class Demo {
public static void main(String[] args) {
// 用户的答案要从键盘输入，因此需要一个键盘输入流
@SuppressWarnings("resource")
Scanner in = new Scanner(System.in);
// 定义一个变量用来统计得分
int sum = 0;
// 通过循环生成10道题
for (int i = 0; i < 10; i++) {
// 随机生成两个10以内的随机数作为被除数和除数
int a = (int) Math.round(Math.random() * 10);
int b = (int) Math.round(Math.random() * 10);
System.out.println(a + "/" + b + "=");
// 定义一个整数用来接收用户输入的答案
int c = in.nextInt();
// 判断用户输入的答案是否正确，正确给10分，错误不给分
if (c == a / b) {
sum += 10;
System.out.println("恭喜答案正确");
}
else {
System.out.println("抱歉，答案错误");
}
}
//输出用户的成绩
System.out.println("你的得分为"+sum);
}
}
package 运算;
public class Yuns {
public int add(int a,int b)
{
return a+b;
}
public int reduce(int a,int b)
{
if((a-b)>0)
return a-b;
else return 0;
}
public int multiply(int a,int b)
{
return a*b;
}
public int devision(int a,int b)
{
if(b!=0)
return a/b;
else return 0;
}
学习总结：通过本周的学习，更懂得了Java的更多知识，也通过同学一起做一个实验时，更快地解决了自己没了解到的内容。
