第十二週Java實驗作業
阿新 • • 發佈：2018-11-11
實驗十一 集合
實驗時間 2018-11-8
1、實驗目的與要求
(1) 掌握Vetor、Stack、Hashtable三個類的用途及常用API；
Vector類類似長度可變的陣列，其中只能存放物件，其中的元素通過下標進行訪問。
Vetor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。
siize集合當前元素個數。
Vector v = new Vector (100);
Stack是Vector的子類。
Stack類描述堆疊資料結構，即
Stack類的關鍵方法：
public void push(Object item)//把棧壓入棧頂
public Object pop()//移除棧頂物件並作為此函式的值返回物件
public Object peek()//檢視棧頂物件而不移除它
Public boolean empty()//推測堆疊是否為空
Hashtable通過鍵來查詢元素。
Hastable用雜湊碼（hastable）來確定鍵。所有物件都有有一個雜湊碼，可以通過Object類的hastable()方法獲得。
(2) 瞭解java集合框架體系組成；
(2) 掌握ArrayList、LinkList兩個類的用途及常用API。
ArrayList可以將其看作是能夠自動增長容量的陣列。
利用ArrayList類的toArray返回一個數組。
Arrays.asList()返回一個列表。
LinkedList是採用雙向迴圈列表實現的。
(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
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；
l 掌握Vetor、Stack、Hashtable三個類的用途及常用API。
出現執行時異常，輸出Dog #7 時，型別不匹配。附上兩種修改方法。
示例程式1：
package 小陳; 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()-1; i++) { System.out.println(cats.get(i).getClass());//獲得類名 //if(cats.get(i).getClass() ) ((Cat) cats.elementAt(i)).print(); } System.out.println(cats.get(7).getClass());//獲得類名 ((Dog) cats.elementAt(7)).print(); } } /*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++) { System.out.println(cats.get(i).getClass());//獲得類名 //if(cats.get(i).getClass() ) ((Cat) cats.elementAt(i)).print(); for ( i = 0; i < cats.size(); i++) { System.out.println(cats.get(i).getClass());//獲得類名 //if(cats.get(i).getClass() ) ((Dog) cats.elementAt(i)).print(); } } System.out.println(cats.get(7).getClass());//獲得類名 ((Dog) cats.elementAt(7)).print(); } }*/ /*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++) { System.out.println(cats.get(i).getClass());//獲得類名 if(cats.elementAt(i) instanceof Cat) { ((Cat) cats.elementAt(i)).print(); }else { ((Dog) cats.elementAt(i)).print(); } } } }*/CatsAndDogs
執行結果：
示例程式2：
package 小陳3.src; 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()); } }Stacks
執行結果：
示例程式3：
package 小陳1; import java.util.*; class Counter { int i = 1;//不加任何訪問許可權修飾符，只允許在同一個包中進行訪問。 public String toString() { return Integer.toString(i); } } public class Statistics { public static void main(String[] args) { Hashtable ht = new Hashtable();//生成雜湊表類物件，雜湊表儲存的資料是鍵值 for (int i = 0; i < 10000; i++) { Integer r = new Integer((int) (Math.random() * 20)); //使用Math.random方法生成整型隨機數r，範圍是0到20 if (ht.containsKey(r)) //通過物件呼叫containsKey()，判斷r值是否是雜湊表裡的鍵值，如果是，返回true，否則返回false ((Counter) ht.get(r)).i++;//獲得雜湊表裡面的鍵值，引用Counter的屬性，輸出r出現的頻次 else ht.put(r, new Counter());//呼叫put方法向雜湊表裡面新增鍵值 } System.out.println(ht); } }Statistics
執行結果：
測試程式3：
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 小陳3; import java.util.*; public class ArrayListDemo { public static void main(String[] argv) { ArrayList<Comparable> al = new ArrayList<Comparable>(); // Add lots of elements to the ArrayList... al.add(new Integer(11));//新增物件元素 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:"); //System.out.println(al.size());//輸出al陣列的長度 for (int i = 0; i < al.size(); i++) { System.out.println("Element " + i + " = " + al.get(i));//get方法存放索引值 } } }ArrayListDemo
執行結果：
package 小陳4; import java.util.*; public class LinkedListDemo { public static void main(String[] argv) { LinkedList l = new LinkedList();//構造一個空連結串列，實質為建立一個數組 l.add(new Object());//呼叫add方法向連結串列新增元素 l.add("Hello"); l.add("zhangsan"); ListIterator li = l.listIterator(0);//構造一個迭代器 while (li.hasNext()) //hasNext() 用於檢查序列中是否還有元素，如果仍然有元素可以迭代，則返回true，返回迭代的下一個元素 System.out.println(li.next());//next()返回當前next()的一個物件 if (l.indexOf("Hello") < 0) System.err.println("Lookup does not work"); else System.err.println("Lookup works"); } }LinkListDemo.
執行結果：
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 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<>();//構造一個空連結串列，實質為建立一個String型別的陣列a a.add("Amy");//呼叫add方法向陣列新增元素 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，將a陣列的內容合併到b中 ListIterator<String> aIter = a.listIterator(); //使用LinkList類的listIterator方法返回一個實現了listIterator介面的迭代器物件 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，從b陣列中刪除第二個單詞 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); } }LinkedListTest
測試程式3：
l 執行SetDemo程式，結合執行結果理解程式；
package 小陳3.src; import java.util.*; public class SetDemo { public static void main(String[] argv) { HashSet h = new HashSet(); //也可以 Set h=new HashSet()
//構造一個空散列表 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()); } } }
執行結果：
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。
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，利用HashSet實現Set介面 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."); } }SetTest
執行結果：
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 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<>();//構造一個空樹集。 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); } }TreeSet
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); } }Item
執行結果：
測試程式4：
l 使用JDK命令執行HashMapDemo程式，結合程式執行結果理解程式；
package treeSet; import java.util.*; public class HashMapDemo { public static void main(String[] argv) { HashMap h = new HashMap();//構造一個空雜湊對映 // The hash maps from company name to address. h.put("Adobe", "Mountain View, CA");//將這些元素插入到對映中 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); } }HashMapDemo
執行結果：
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；
瞭解HashMap、TreeMap兩個類的用途及常用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<>();//為儲存的員工資訊建立一個雜湊對映 staff.put("144-25-5464", new Employee("Amy Lee"));//a將員工資訊新增到對映中 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)); } }MapTest
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 + "]"; } }Employee
執行結果：
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；
l 採用結對程式設計方式，與學習夥伴合作完成實驗九程式設計練習1；
l 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。
合作伙伴：王燕
合作伙伴的程式碼：
身份證號檔案處理：
package 看到誰; 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 Check{ private static ArrayList<Student> studentlist; public static void main(String[] args) { studentlist = new ArrayList<>(); Scanner scanner = new Scanner(System.in); File file = new File("C:\\下載\\身份證號.txt");//檔案讀取 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) {//捕獲異常 System.out.println("學生資訊檔案找不到"); e.printStackTrace(); } catch (IOException e) { System.out.println("學生資訊檔案讀取錯誤"); e.printStackTrace(); } //加入異常處理機制，維護程式碼的健壯性 boolean isTrue = true; //選擇所要進行的操作 while (isTrue) { System.out.println("選擇你的操作，輸入正確格式的選項"); System.out.println("1.按姓名字典序輸出人員資訊"); System.out.println("2.輸出年齡最大和年齡最小的人"); System.out.println("3.查詢老鄉"); System.out.println("4.查詢年齡相近的人"); System.out.println("5.退出"); String m = scanner.next(); switch (m) { case "1": Collections.sort(studentlist); System.out.println(studentlist.toString()); break; case "2": 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("年齡最大："+studentlist.get(k1)); System.out.println("年齡最小："+studentlist.get(k2)); break; case "3": System.out.println("輸入省份"); 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("老鄉"+studentlist.get(i)); } break; case "4": System.out.println("年齡："); int yourage = scanner.nextInt(); int near=agenear(yourage); int value=yourage-studentlist.get(near).getage(); System.out.println(""+studentlist.get(near)); 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,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; } }Check
package 看到誰; 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()); }//對姓名進行字典排序 public String toString() { return name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n"; } }Student
簡易計算器：
package 看到誰; import java.io.FileNotFoundException; import java.io.PrintWriter; import java.util.Scanner; public class Caculator { public static void main(String[] args) { Scanner in = new Scanner(System.in); Caculator1 computing=new Caculator1(); PrintWriter output = null; //使用了異常處理機制，增強程式碼的安全性 try { output = new PrintWriter("Caculator.txt"); } catch (Exception e) { } int sum = 0; //隨機數生成，提供後續題目所用的資料 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); //選擇所要進行的操作 switch(s)//s為隨機數，可隨機執行下面四種操作 { case 1: System.out.println(i+": "+a+"/"+b+"="); while(b==0){ b = (int) Math.round(Math.random() * 100); } double c = in.nextDouble(); output.println(a+"/"+b+"="+c); //修改建議:生成除法題目時，對a，b兩個數進行條件判斷，確保整除，還有除數不為0 if (c == (double)computing.division(a, b)) { sum += 10; System.out.println("T"); } else { System.out.println("F"); } break; // case 2: System.out.println(i+": "+a+"*"+b+"="); int c1 = in.nextInt(); output.println(a+"*"+b+"="+c1); if (c1 == computing.multiplication(a, b)) { sum += 10; System.out.println("T"); } else { System.out.println("F"); } break; case 3: System.out.println(i+": "+a+"+"+b+"="); int c2 = in.nextInt(); output.println(a+"+"+b+"="+c2); if (c2 == computing.addition(a, b)) { sum += 10; System.out.println("T"); } else { System.out.println("F"); } break ; case 4: System.out.println(i+": "+a+"-"+b+"="); int c3 = in.nextInt(); output.println(a+"-"+b+"="+c3); if (c3 == computing.subtraction(a, b)) { sum += 10; System.out.println("T"); } else { System.out.println("F"); } break ; } } System.out.println("scores："+sum); output.println("scores："+sum); output.close(); } } class Caculator1 { private int a; private int b; public int addition(int a,int b) { return a+b; } public int subtraction(int a,int b) { if((a-b)<0) return 0; else return a-b; } public int multiplication(int a,int b) { return a*b; } public int division(int a,int b) { if(b!=0) return a/b; else return 0; } }四則運算
合作程式碼：
身份證號檔案處理：
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 Identity{ private static ArrayList<Student> studentlist; public static void main(String[] args) { studentlist = new ArrayList<>(); Scanner scanner = new Scanner(System.in); File file = new File("C:/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 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("學生資訊檔案找不到"); e.printStackTrace(); } catch (IOException e) { System.out.println("學生資訊檔案讀取錯誤"); e.printStackTrace(); } boolean isTrue = true; while (isTrue) { System.out.println("選擇你的操作，輸入正確格式的選項"); System.out.println("1.字典排序"); System.out.println("2.輸出年齡最大和年齡最小的人"); System.out.println("3.尋找老鄉"); System.out.println("4.尋找年齡相近的人"); System.out.println("0.退出"); int status = scanner.nextInt(); switch (status) { case 1: Collections.sort(studentlist); System.out.println(studentlist.toString()); break; case 2: 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("年齡最大："+studentlist.get(k1)); System.out.println("年齡最小："+studentlist.get(k2)); break; case 3: 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("老鄉"+studentlist.get(i)); } break; case 4: System.out.println("年齡："); int yourage = scanner.nextInt(); int near=agenear(yourage); int value=yourage-studentlist.get(near).getage(); System.out.println(""+studentlist.get(near)); break; case 0: status = 0; System.out.println("程式已退出!"); break; default: System.out.println("輸入錯誤"); } } } public static int agenear(int age) { int 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; } }Identity
package 看到誰; 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 ) { this.age=age ; } public String getprovince() { return province; } public void setprovince(String province) { this.province=province ; } @Override public int compareTo(Student other) { // TODO Auto-generated method stub return this.name.compareTo(other.getName()); } public String toString() { return name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n"; } }Student
執行結果：
簡易計算器：
import java.io.FileNotFoundException; import java.io.PrintWriter; import java.util.Scanner; public class Caculator { public static void main(String[] args) { Scanner in = new Scanner(System.in); Caculator1 computing=new Caculator1(); PrintWriter output = null; try { output = new PrintWriter("Caculator.txt"); } catch (Exception e) { } int sum = 0; 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+"="); while(b==0){ b = (int) Math.round(Math.random() * 100); } double c = in.nextDouble(); output.println(a+"/"+b+"="+c); if (c == (double)computing.division(a, b)) { sum += 10; System.out.println("T"); } else { System.out.println("F"); } break; case 2: System.out.println(i+": "+a+"*"+b+"="); int c1 = in.nextInt(); output.println(a+"*"+b+"="+c1); if (c1 == computing.multiplication(a, b)) { sum += 10; System.out.println("T"); } else { System.out.println("F"); } break; case 3: System.out.println(i+": "+a+"+"+b+"="); int c2 = in.nextInt(); output.println(a+"+"+b+"="+c2); if (c2 == computing.addition(a, b)) { sum += 10; System.out.println("T"); } else { System.out.println(