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  • 王志成/王之泰《面向对象程序设计(java)》第十一周学习总结

    理论学习部分:

    JAVA的集合框架

    l JAVA的集合框架实现对各种数据结构的封装,以降低对数据管理与处理的难度。

    l 所谓框架就是一个类库的集合,框架中包含很多超类,编程者创建这些超类的子类可较方便的设计设计程序所需的类。例如:Swing类包

    l 集合(Collection或称为容器)是一种包含多个元素并提供对所包含元素操作方法的类,其包含的元素可以由同一类型的对象组成,也可以由不同类型的对象组成。

    l 集合框架:JAVA集合类库的统一架构。

    1.集合类的作用

    l 集合类的作用: 

    – Java的集合类提供了一些基本数据结构的支持。

    – 例如Vector、Hashtable、Stack等。

    l 集合类的使用:

    – Java的集合类包含在java.util包中。

    – import java.util.*;

    2.集合类的特点

    l 特点一:

    – 只容纳对象。

    注意:数组可以容纳基本数据类型数据和对象。

    – 如果集合类中想使用基本数据类型,又想利用集合类的灵活性,可以把基本数据类型数据封装成该数据类型的包装器对象,然后放入集合中处理。

    l 特点二: 

    – 集合类容纳的对象都是Object类的实例,一旦把一个对象置入集合类中,它的类信息将丢失,这样设计的目的是为了集合类的通用性。

    – 因为Object类是所有类的祖先,所以可以在这些集合中存放任何类的对象而不受限制,但切记在使用集合成员之前必须对它重新造型。

    3. 新旧集合类

    Vector类

    Stack类

    Hashtable类

    Vector类 
     Vector类类似长度可变的数组。
     Vector中只能存放对象。  Vector的元素通过下标进行访问。
     Vector类关键属性: – capacity表示集合最多能容纳的元素个数。 – capacityIncrement表示每次增加多少容量。 – size表示集合当前元素个数。
    Vector v = new Vector(100)

    1、实验目的与要求

    (1) 掌握VetorStackHashtable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ArrayListLinkList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HashMapTreeMap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:

    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VetorStackHashtable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();
        }
    }

    修改为:

    package 王志成;
    
    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++) {
                if(cats.elementAt(i) instanceof Cat) {
                    
                    ((Cat) cats.elementAt(i)).print();
                
                }else {
                    
                    ((Dog) cats.elementAt(i)).print();
                
                }
            }
                
        
        }
    }

    package 王志成;
    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 王志成;
    
    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);
        }
    }

    测试程序2:

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

    package 王志成;
    import java.util.*;
    
    public class ArrayListDemo {
        public static void main(String[] argv) {
            ArrayList<Comparable> 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));
            }
        }
    }

    package 王志成;
    
    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");
       }
    }

    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;

    掌握ArrayListLinkList两个类的用途及常用API

    package 王志成;
    
    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:

    运行SetDemo程序,结合运行结果理解程序;

    package 王志成;
    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());
            }
        }
    }

    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

    Elipse环境下调试教材367-368程序9-39-4,结合程序运行结果理解程序;了解TreeSet类的用途及常用API

    package 王志成;
    
    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.");
       }
    }

    Elipse环境下调试教材367-368程序9-39-4,结合程序运行结果理解程序;了解TreeSet类的用途及常用API

    package 王志成;
    
    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);
       }
    }
    package 王志成;
    
    import java.util.*;
    
    /**
     * An item with a description and a part number.
     */
    public class Item implements Comparable<Item>//Item类实现Comparable接口
    {
       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;//字符串
          partNumber = aPartNumber;
       }
    
       /**
        * Gets the description of this item.
        * 
        * @return the description
        */
       public String getDescription()
       {
          return description;
       }
    
       public String toString()
       {
          return "[description=" + description + ", partNumber=" + partNumber + "]";
       }//返回该对象的字符串表示
    
       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);
       }
    }
    
    

    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;

    package 王志成;
    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);
      }
    }

    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;

    了解HashMapTreeMap两个类的用途及常用API

    package 王志成;
    
    import java.util.*;
    
    /**
     * This program demonstrates how to extend the collections framework.
     * @version 1.21 2012-01-26
     * @author Cay Horstmann
     */
    public class CircularArrayQueueTest
    {
       public static void main(String[] args)
       {
          Queue<String> q = new CircularArrayQueue<>(5);
          q.add("Amy");
          q.add("Bob");
          q.add("Carl");
          q.add("Deedee");
          q.add("Emile");
          q.remove();
          q.add("Fifi");
          q.remove();
          for (String s : q) System.out.println(s);
       }
    }
    
    /** 
        A first-in, first-out bounded collection. 
    */ 
    class CircularArrayQueue<E> extends AbstractQueue<E>
    { 
       private Object[] elements; 
       private int head; 
       private int tail; 
       private int count; 
       private int modcount;
    
       /** 
           Constructs an empty queue. 
           @param capacity the maximum capacity of the queue 
       */ 
       public CircularArrayQueue(int capacity) 
       { 
          elements = new Object[capacity]; 
          count = 0; 
          head = 0; 
          tail = 0; 
       } 
    
       public boolean offer(E newElement) 
       { 
          assert newElement != null;
          if (count < elements.length) 
          {
             elements[tail] = newElement; 
             tail = (tail + 1) % elements.length; 
             count++;
             modcount++;
             return true;
          }
          else 
             return false;
       } 
    
       public E poll() 
       { 
          if (count == 0) return null;
          E r = peek(); 
          head = (head + 1) % elements.length; 
          count--; 
          modcount++;
          return r; 
       } 
    
       @SuppressWarnings("unchecked")
       public E peek() 
       { 
          if (count == 0) return null;
          return (E) elements[head]; 
       } 
    
       public int size() 
       { 
          return count; 
       } 
    
       public Iterator<E> iterator()
       {
          return new QueueIterator();
             
       }
    
       private class QueueIterator implements Iterator<E>
       {
          private int offset;
          private int modcountAtConstruction;
    
          public QueueIterator()
          {
             modcountAtConstruction = modcount;
          }
    
          @SuppressWarnings("unchecked")
          public E next() 
          { 
             if (!hasNext()) throw new NoSuchElementException();
             E r = (E) elements[(head + offset) % elements.length]; 
             offset++;
             return r;
          }
    
          public boolean hasNext() 
          { 
             if (modcount != modcountAtConstruction) 
                throw new ConcurrentModificationException();
             return offset < count;
          }
    
          public void remove() 
          { 
             throw new UnsupportedOperationException(); 
          }
       }
    }

    实验2:结对编程练习:

    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。

     

    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

    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。

    确定本次实验结对编程合作伙伴;

    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;

    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;

    合作伙伴:王之泰

    合作伙伴的实验代码及结果如下:

    实验九:

    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.Arrays;
    import java.util.Collections;
    import java.util.Scanner;
    
    public class main{
        private static ArrayList<person> Personlist;
        public static void main(String[] args) {
            Personlist = new ArrayList<>();
            Scanner scanner = new Scanner(System.in);
            File file = new File("D:\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 ID = linescanner.next();
                    String sex = linescanner.next();
                    String age = linescanner.next();
                    String place =linescanner.nextLine();
                    person Person = new person();
                    Person.setname(name);
                    Person.setID(ID);
                    Person.setsex(sex);
                    int a = Integer.parseInt(age);
                    Person.setage(a);
                    Person.setbirthplace(place);
                    Personlist.add(Person);
    
                }
            } catch (FileNotFoundException e) {
                System.out.println("查找不到信息");
                e.printStackTrace();
            } catch (IOException e) {
                System.out.println("信息读取有误");
                e.printStackTrace();
            }
            boolean isTrue = true;
            while (isTrue) {
                System.out.println("1:按姓名字典序输出人员信息");
                System.out.println("2:查询最大年龄与最小年龄人员信息");
                System.out.println("3:输入你的年龄,查询与你最近人的姓名、身份证号、年龄、性别和出生地;");
                System.out.println("4:查询是否有同乡");
                System.out.println("5:退出");
                int nextInt = scanner.nextInt();
                switch (nextInt) {
                case 1:
                    Collections.sort(Personlist);
                    System.out.println(Personlist.toString());
                    break;
                case 2:
                    
                    int max=0,min=100;int j,k1 = 0,k2=0;
                    for(int i=1;i<Personlist.size();i++)
                    {
                        j=Personlist.get(i).getage();
                       if(j>max)
                       {
                           max=j; 
                           k1=i;
                       }
                       if(j<min)
                       {
                           min=j; 
                           k2=i;
                       }
    
                    }  
                    System.out.println("年龄最大:"+Personlist.get(k1));
                    System.out.println("年龄最小:"+Personlist.get(k2));
                    break;
                case 3:
                    System.out.println("年龄:");
                    int yourage = scanner.nextInt();
                    int near=agenear(yourage);
                    int d=yourage-Personlist.get(near).getage();
                    System.out.println(""+Personlist.get(near));
                    break;
                case 4:
                    System.out.println("你的家乡?");
                    String find = scanner.next();        
                    String place=find.substring(0,3);
                    String place2=find.substring(0,3);
                    for (int i = 0; i <Personlist.size(); i++) 
                    {
                        if(Personlist.get(i).getbirthplace().substring(1,4).equals(place)) 
                            System.out.println(""+Personlist.get(i));
    
                    } 
    
                    break;
                case 5:
               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,d=0,k=0;
            for (int i = 0; i < Personlist.size(); i++)
            {
                d=Personlist.get(i).getage()-age;
                if(d<0) d=-d; 
                if (d<min) 
                {
                   min=d;
                   k=i;
                }
    
             }    return k;
            
         }
    
     
    }
    public class person implements Comparable<person> {
    private String name;
    private String ID;
    private int age;
    private String sex;
    private String birthplace;
    
    public String getname() {
    return name;
    }
    public void setname(String name) {
    this.name = name;
    }
    public String getID() {
    return ID;
    }
    public void setID(String ID) {
    this.ID= ID;
    }
    public int getage() {
    
    return age;
    }
    public void setage(int age) {
        // int a = Integer.parseInt(age);
    this.age= age;
    }
    public String getsex() {
    return sex;
    }
    public void setsex(String sex) {
    this.sex= sex;
    }
    public String getbirthplace() {
    return birthplace;
    }
    public void setbirthplace(String birthplace) {
    this.birthplace= birthplace;
    }
    
    public int compareTo(person o) {
       return this.name.compareTo(o.getname());
    
    }
    
    public String toString() {
        return  name+"	"+sex+"	"+age+"	"+ID+"	"+birthplace+"
    ";
    
    }
    
    
    
    }

     实验十

    
    

    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.PrintWriter;
    import java.math.BigDecimal;
    import java.util.Scanner;

    
    


    public class ss {
    public static void main(String[] args) {

    
    


    Scanner in = new Scanner(System.in);
    Calculator<Integer> sf = new Calculator<Integer>();
    File file = new File("wzt.txt");
    if(file.exists()) {
    System.out.println("文件已存在");
    }
    PrintWriter output = null;
    try {
    output = new PrintWriter(new FileOutputStream(file));
    } catch (Exception e) {
    //e.printStackTrace();
    }
    int sum = 0;

    System.out.println("计算结果保留两位小数");
    for (int i = 1; i < 11; i++) {
    int a = (int) Math.round(Math.random() * 100);
    int b = (int) Math.round(Math.random() * 100);
    int s = (int) Math.round(Math.random() * 3);

    
    


    switch(s)
    {
    case 1:
    System.out.println(i+": "+a+"/"+b+"=");
    Number c = in.nextDouble();
    output.println(a+"/"+b+"="+c);
    Number g = sf.division(a, b);
    BigDecimal division = new BigDecimal(g.doubleValue());
    g = division.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
    if (c.equals(g)) {
    sum += 10;
    System.out.println("恭喜答案正确");
    }
    else {
    System.out.println("抱歉,答案错误");
    }

    break;

    case 2:
    System.out.println(i+": "+a+"*"+b+"=");
    Number c1 = in.nextDouble();
    output.println(a+"*"+b+"="+c1);
    Number g1 = sf.mulitiplication(a, b);
    BigDecimal mul = new BigDecimal(g1.doubleValue());
    g1 = mul.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
    if (c1.equals(g1) ){
    sum += 10;
    System.out.println("恭喜答案正确");
    }
    else {
    System.out.println("抱歉,答案错误");
    }
    break;
    case 3:
    System.out.println(i+": "+a+"+"+b+"=");
    Number c2 = in.nextDouble();
    output.println(a+"+"+b+"="+c2);
    Number g2 =sf.addition(a, b);
    BigDecimal add = new BigDecimal(g2.doubleValue());
    g2 = add.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
    if (c2.equals(g2)) {
    sum += 10;
    System.out.println("恭喜答案正确");
    }
    else {
    System.out.println("抱歉,答案错误");
    }

    break ;
    case 4:
    System.out.println(i+": "+a+"-"+b+"=");
    Number c3 = in.nextDouble();
    output.println(a+"-"+b+"="+c3);
    Number g3 = sf.subtraction(a, b);
    BigDecimal sub = new BigDecimal(g3.doubleValue());
    g3 = sub.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
    if (c3.equals(g3)) {
    sum += 10;
    System.out.println("恭喜答案正确");
    }
    else {
    System.out.println("抱歉,答案错误");
    }
    break ;

    
    

    }

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

    }
    }

    
    
    public class Calculator<T> {
        
        public Calculator() {
            // TODO Auto-generated constructor stub
        }
        
        
        public Number addition(T m,T n) {
            return Double.parseDouble(m.toString())+Double.parseDouble(n.toString());
        }
    
        public Number subtraction(T m,T n) {
            return Double.parseDouble(m.toString())-Double.parseDouble(n.toString());
        }
        public Number mulitiplication(T m,T n) {
            return Double.parseDouble(m.toString())*Double.parseDouble(n.toString());
        }
        public Number division(T m,T n) {
            if(Double.parseDouble(n.toString()) != 0)
            return Double.parseDouble(m.toString())/Double.parseDouble(n.toString());
            else
            return 0;
        }
    }

    完善意见:通过运行他的实验代码,可以看出他的代码写得很完善,很严谨,但或许会有一丝繁琐,可以适当的简化,但对现阶段的我们来说,这样或许更好的能帮助我们加深所学知识的理解。

    结对编程代码如下:

    package jiedui_bianchen;
    
    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.Scanner;
    import java.util.Collections;
    
    public class ID {
    
        public static People findPeopleByname(String name) {
            People flag = null;
            for (People people : peoplelist) {
                if(people.getName().equals(name)) {
                    flag = people;
                }
            }
            return flag;
    
        }
    
        public static People findPeopleByid(String id) {
            People flag = null;
            for (People people : peoplelist) {
                if(people.getnumber().equals(id)) {
                    flag = people;
                }
            }
            return flag;
    
        }
         
        private static ArrayList<People> agenear(int yourage) {
            // TODO Auto-generated method stub
            int j=0,min=53,d_value=0,k = 0;
            ArrayList<People> plist = new ArrayList<People>();
            for (int i = 0; i < peoplelist.size(); i++) {
                d_value = peoplelist.get(i).getage() > yourage ? 
                        peoplelist.get(i).getage() - yourage : yourage - peoplelist.get(i).getage() ;
                k = d_value < min ? i : k;
                min = d_value < min ? d_value : min;
            }
            for(People people : peoplelist) {
                if(people.getage() == peoplelist.get(k).getage()) {
                    plist.add(people);
                }
            }
            return plist;
        }
    
        private static ArrayList<People> peoplelist; 
        
        public static void main(String[] args) //throws  IOException
        {
            peoplelist = new ArrayList<People>();
            Scanner scanner = new Scanner(System.in);
            File file = new File("D:\身份证号.txt");
            try {
                FileInputStream files = new FileInputStream(file);
                BufferedReader in = new BufferedReader(new InputStreamReader(files));
                String temp = null;
                while ((temp = in.readLine()) != null) {
                    
                    String[] information = temp.split("[ ]+");
                    People people = new People();
                    people.setName(information[0]);
                    people.setnumber(information[1]);
                    int A = Integer.parseInt(information[3]);
                    people.setage(A);
                    people.setsex(information[2]);
                    for(int j = 4; j<information.length;j++) {
                        people.setplace(information[j]);
                    }
                    peoplelist.add(people);
    
                }
            } catch (FileNotFoundException e) {
                System.out.println("文件未找到");
                e.printStackTrace();
            } catch (IOException e) {
                System.out.println("文件读取错误");
                e.printStackTrace();
            }
            boolean isTrue = true;
            while (isTrue) {
    
                System.out.println("******************************************");
                System.out.println("   1.按姓名典序输出人员信息");
                System.out.println("   2.查询最大年龄人员信息");
                System.out.println("   3.查询最小年龄人员信息");
                System.out.println("   4.输入你的年龄,查询身份证号.txt中年龄与你最近的人");
                System.out.println("   5.查询人员中是否有你的同乡");
                System.out.println("   6.退出");
                System.out.println("******************************************");
                int nextInt = scanner.nextInt();
                switch (nextInt) {
                case 1:
                    Collections.sort(peoplelist);
                    System.out.println(peoplelist.toString());
                    break;
                case 2:
                    int max=0;
                    int j,k1 = 0;
                    for(int i=1;i<peoplelist.size();i++)
                    {
                        j = peoplelist.get(i).getage();
                       if(j>max)
                       {
                           max = j; 
                           k1 = i;
                       }
                      
                    }  
                    System.out.println("年龄最大:"+peoplelist.get(k1));
                    break;
                case 3:
                    int min = 100;
                    int j1,k2 = 0;
                    for(int i=1;i<peoplelist.size();i++)
                    {
                        j1 = peoplelist.get(i).getage();
                        if(j1<min)
                        {
                            min = j1; 
                            k2 = i;
                        }
    
                     } 
                    System.out.println("年龄最小:"+peoplelist.get(k2));
                    break;
                case 4:
                    System.out.println("年龄:");
                    int input_age = scanner.nextInt();
                    ArrayList<People> plist = new ArrayList<People>();
                    plist = agenear(input_age);
                    for(People people : plist) {
                        System.out.println(people.toString());
                    }
                    break;
                case 5:
                    System.out.println("请输入省份");
                    String find = scanner.next();        
                    for (int i = 0; i <peoplelist.size(); i++) 
                    {
                        String [] place = peoplelist.get(i).getplace().split("	");
                        for(String temp : place) {
                            if(find.equals(temp)) {
                                System.out.println("你的同乡是    "+peoplelist.get(i));
                                break;
                            }
                        }
                        
                    } 
                    break;
                case 6:
                    isTrue = false;
                    System.out.println("byebye!");
                    break;
                default:
                    System.out.println("输入有误");
                }
            }
        }
    
    }

    结对程序运行功能界面截图;

    结对过程描述,提供两人在讨论、细化和编程时的结对照片(非摆拍)。

    5.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。

    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.PrintWriter;
    import java.math.BigDecimal;
    import java.util.Scanner;
    
    
    public class ss {
        public static void main(String[] args) {
    
    
            Scanner in = new Scanner(System.in);
            Calculator<Integer> sf = new Calculator<Integer>();
            File file = new File("wzt.txt");
            if(file.exists()) {
                System.out.println("文件已存在");
            }
            PrintWriter output = null;
            try {
                output = new PrintWriter(new FileOutputStream(file));
            } catch (Exception e) {
                //e.printStackTrace();
            }
            int sum = 0;
            
            System.out.println("计算结果保留两位小数");
            for (int i = 1; i < 11; i++) {
                int a = (int) Math.round(Math.random() * 100);
                    int b = (int) Math.round(Math.random() * 100);
                    int s = (int) Math.round(Math.random() * 3);
    
                
               switch(s)
               {
               case 1:
                   System.out.println(i+": "+a+"/"+b+"=");
                   Number c = in.nextDouble();
                   output.println(a+"/"+b+"="+c);
                   Number g = sf.division(a, b);
                   BigDecimal division = new BigDecimal(g.doubleValue());
                   g = division.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
                   if (c.equals(g)) {
                       sum += 10;
                       System.out.println("恭喜答案正确");
                   }
                   else {
                       System.out.println("抱歉,答案错误");
                   }
                
                   break;
                
               case 2:
                   System.out.println(i+": "+a+"*"+b+"=");
                   Number c1 = in.nextDouble();
                   output.println(a+"*"+b+"="+c1);
                   Number g1 = sf.mulitiplication(a, b);
                   BigDecimal mul = new BigDecimal(g1.doubleValue());
                   g1 = mul.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
                   if (c1.equals(g1) ){
                       sum += 10;
                       System.out.println("恭喜答案正确");
                   }
                   else {
                       System.out.println("抱歉,答案错误");
                   }
                   break;
               case 3:
                   System.out.println(i+": "+a+"+"+b+"=");
                   Number c2 = in.nextDouble();
                   output.println(a+"+"+b+"="+c2);
                   Number g2 =sf.addition(a, b);
                   BigDecimal add = new BigDecimal(g2.doubleValue());
                   g2 = add.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
                   if (c2.equals(g2)) {
                       sum += 10;
                       System.out.println("恭喜答案正确");
                   }
                   else {
                       System.out.println("抱歉,答案错误");
                   }
                   
                   break ;
               case 4:
                   System.out.println(i+": "+a+"-"+b+"=");
                   Number c3 = in.nextDouble();
                   output.println(a+"-"+b+"="+c3);
                   Number g3 = sf.subtraction(a, b);
                   BigDecimal sub = new BigDecimal(g3.doubleValue());
                   g3 = sub.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
                   if (c3.equals(g3)) {
                       sum += 10;
                       System.out.println("恭喜答案正确");
                   }
                   else {
                       System.out.println("抱歉,答案错误");
                   }
                   break ;
    
                   } 
        
              }
            System.out.println("成绩"+sum);
            output.println("成绩:"+sum);
            output.close();
            in.close();
             
        }
    }

    结对程序运行功能界面截图;

    结对过程描述,提供两人在讨论、细化和编程时的结对照片(非摆拍)。

     总结 :通过这周的Java课程的学习,基本掌握了java中集合的概念,学习了集合的知识以及使用方法。实验中,运用了结对编程的方法,  通过结对编程,极大的提高了我们的编程兴趣,和编程效率,是一种很好的编程方式。

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  • 原文地址:https://www.cnblogs.com/847118824wang/p/9941802.html
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