王志成/王之泰《面向物件程式設計(java)》第十一週學習總結
理論學習部分:
JAVA的集合框架
l JAVA的集合框架實現對各種資料結構的封裝,以降低對資料管理與處理的難度。
l 所謂框架就是一個類庫的集合,框架中包含很多超類,程式設計者建立這些超類的子類可較方便的設計設計程式所需的類。例如:Swing類包
l 集合(Collection或稱為容器)是一種包含多個元素並提供對所包含元素操作方法的類,其包含的元素可以由同一型別的物件組成,也可以由不同型別的物件組成。
l 集合框架:JAVA集合類庫的統一架構。
1.集合類的作用
l 集合類的作用:
– Java的集合類提供了一些基本資料結構的支援。
– 例如Vector、Hashtable、Stack等。
l 集合類的使用:
– Java的集合類包含在java.util包中。
– import java.util.*;
2.集合類的特點
l 特點一:
– 只容納物件。
注意:陣列可以容納基本資料型別資料和物件。
– 如果集合類中想使用基本資料型別,又想利用集合類的靈活性,可以把基本資料型別資料封裝成該資料型別的包裝器物件,然後放入集合中處理。
l 特點二:
– 集合類容納的物件都是Object類的例項,一旦把一個物件置入集合類中,它的類資訊將丟失,這樣設計的目的是為了集合類的通用性。
– 因為Object類是所有類的祖先,所以可以在這些集合中存放任何類的物件而不受限制,但切記在使用集合成員之前必須對它重新造型。
3. 新舊集合類
Vector類
Stack類
Hashtable類
Vector類
Vector類類似長度可變的陣列。
Vector中只能存放物件。 Vector的元素通過下標進行訪問。
Vector類關鍵屬性: – capacity表示集合最多能容納的元素個數。 – capacityIncrement表示每次增加多少容量。 – size表示集合當前元素個數。
Vector v = new Vector(100)
1、實驗目的與要求
(1) 掌握Vetor、Stack、Hashtable三個類的用途及常用API;
(2) 瞭解java集合框架體系組成;
(3) 掌握ArrayList、LinkList兩個類的用途及常用API。
(4) 瞭解HashSet類、TreeSet類的用途及常用API。
(5)瞭解HashMap、TreeMap兩個類的用途及常用API;
(6) 結對程式設計(Pair programming)練習,體驗程式開發中的兩人合作。
2、實驗內容和步驟
實驗1: 匯入第9章示例程式,測試程式並進行程式碼註釋。
測試程式1:
l 使用JDK命令執行編輯、執行以下三個示例程式,結合執行結果理解程式;
掌握Vetor、Stack、Hashtable三個類的用途及常用API。
//示例程式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(); } }
修改為:
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); } }
測試程式2:
l 使用JDK命令編輯執行ArrayListDemo和LinkedListDemo兩個程式,結合程式執行結果理解程式;
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"); } }
l 在Elipse環境下編輯執行除錯教材360頁程式9-1,結合程式執行結果理解程式;
l 掌握ArrayList、LinkList兩個類的用途及常用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); } }
測試程式3:
l 執行SetDemo程式,結合執行結果理解程式;
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()); } } }
l 在Elipse環境下除錯教材365頁程式9-2,結合執行結果理解程式;瞭解HashSet類的用途及常用API。
l 在Elipse環境下除錯教材367頁-368程式9-3、9-4,結合程式執行結果理解程式;瞭解TreeSet類的用途及常用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."); } }
l 在Elipse環境下除錯教材367頁-368程式9-3、9-4,結合程式執行結果理解程式;瞭解TreeSet類的用途及常用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類實現Comparable介面 { 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 + "]"; }//返回該物件的字串表示 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); } }
測試程式4:
使用JDK命令執行HashMapDemo程式,結合程式執行結果理解程式;
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); } }
l 在Elipse環境下除錯教材373頁程式9-6,結合程式執行結果理解程式;
l 瞭解HashMap、TreeMap兩個類的用途及常用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(); } } }
實驗2:結對程式設計練習:
l 關於結對程式設計:以下圖片是一個結對程式設計場景:兩位學習夥伴坐在一起,面對著同一臺顯示器,使用著同一鍵盤,同一個滑鼠,他們一起思考問題,一起分析問題,一起編寫程式。
l 關於結對程式設計的闡述可參見以下連結:
http://www.cnblogs.com/xinz/archive/2011/08/07/2130332.html
http://en.wikipedia.org/wiki/Pair_programming
l 對於結對程式設計中程式碼設計規範的要求參考:
http://www.cnblogs.com/xinz/archive/2011/11/20/2255971.html
以下實驗,就讓我們來體驗一下結對程式設計的魅力。
l 確定本次實驗結對程式設計合作伙伴;
l 各自執行合作伙伴實驗九程式設計練習1,結合使用體驗對所執行程式提出完善建議;
l 各自執行合作伙伴實驗十程式設計練習2,結合使用體驗對所執行程式提出完善建議;
合作伙伴:王之泰
合作伙伴的實驗程式碼及結果如下:
實驗九:
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:\\身份證號.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("查詢不到資訊"); e.printStackTrace(); } catch (IOException e) { System.out.println("資訊讀取有誤"); e.printStackTrace(); } boolean isTrue = true; while (isTrue) { System.out.println("1:按姓名字典序輸出人員資訊"); System.out.println("2:查詢最大年齡與最小年齡人員資訊"); System.out.println("3:輸入你的年齡,查詢與你最近人的姓名、身份證號、年齡、性別和出生地;"); System.out.println("4:查詢是否有同鄉"); 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("年齡最大:"+Personlist.get(k1)); System.out.println("年齡最小:"+Personlist.get(k2)); break; case 3: System.out.println("年齡:"); 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("你的家鄉?"); 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("退出程式!"); break; default: System.out.println("輸入有誤"); } } } 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+"\t"+sex+"\t"+age+"\t"+ID+"\t"+birthplace+"\n"; } }
實驗十
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("檔案已存在");
}
PrintWriter output = null;
try {
output = new PrintWriter(new FileOutputStream(file));
} catch (Exception e) {
//e.printStackTrace();
}
int sum = 0;
System.out.println("計算結果保留兩位小數");
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("恭喜答案正確");
}
else {
System.out.println("抱歉,答案錯誤");
}
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("恭喜答案正確");
}
else {
System.out.println("抱歉,答案錯誤");
}
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("恭喜答案正確");
}
else {
System.out.println("抱歉,答案錯誤");
}
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("恭喜答案正確");
}
else {
System.out.println("抱歉,答案錯誤");
}
break ;
}
}
System.out.println("成績"+sum);
output.println("成績:"+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; } }
完善意見:通過執行他的實驗程式碼,可以看出他的程式碼寫得很完善,很嚴謹,但或許會有一絲繁瑣,可以適當的簡化,但對現階段的我們來說,這樣或許更好的能幫助我們加深所學知識的理解。
結對程式設計程式碼如下:
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:\\身份證號.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("檔案未找到"); e.printStackTrace(); } catch (IOException e) { System.out.println("檔案讀取錯誤"); e.printStackTrace(); } boolean isTrue = true; while (isTrue) { System.out.println("******************************************"); System.out.println(" 1.按姓名典序輸出人員資訊"); System.out.println(" 2.查詢最大年齡人員資訊"); System.out.println(" 3.查詢最小年齡人員資訊"); System.out.println(" 4.輸入你的年齡,查詢身份證號.txt中年齡與你最近的人"); System.out.println(" 5.查詢人員中是否有你的同鄉"); 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("年齡最大:"+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("年齡最小:"+peoplelist.get(k2)); break; case 4: System.out.println("年齡:"); 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("請輸入省份"); String find = scanner.next(); for (int i = 0; i <peoplelist.size(); i++) { String [] place = peoplelist.get(i).getplace().split("\t"); for(String temp : place) { if(find.equals(temp)) { System.out.println("你的同鄉是 "+peoplelist.get(i)); break; } } } break; case 6: isTrue = false; System.out.println("byebye!"); break; default: System.out.println("輸入有誤"); } } } }
結對程式執行功能介面截圖;
結對過程描述,提供兩人在討論、細化和程式設計時的結對照片(非擺拍)。
5.採用結對程式設計方式,與學習夥伴合作完成實驗十程式設計練習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("檔案已存在"); } PrintWriter output = null; try { output = new PrintWriter(new FileOutputStream(file)); } catch (Exception e) { //e.printStackTrace(); } int sum = 0; System.out.println("計算結果保留兩位小數"); 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("恭喜答案正確"); } else { System.out.println("抱歉,答案錯誤"); } 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("恭喜答案正確"); } else { System.out.println("抱歉,答案錯誤"); } 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("恭喜答案正確"); } else { System.out.println("抱歉,答案錯誤"); } 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("恭喜答案正確"); } else { System.out.println("抱歉,答案錯誤"); } break ; } } System.out.println("成績"+sum); output.println("成績:"+sum); output.close(); in.close(); } }
結對程式執行功能介面截圖;
結對過程描述,提供兩人在討論、細化和程式設計時的結對照片(非擺拍)。
總結 :通過這周的Java課程的學習,基本掌握了java中集合的概念,學習了集合的知識以及使用方法。實驗中,運用了結對程式設計的方法, 通過結對程式設計,極大的提高了我們的程式設計興趣,和程式設計效率,是一種很好的程式設計方式。