package pair1;/*** @version 1.00 2004-05-10* @author Cay Horstmann*/
public class Pair<T> //Pair类引入了一个类型变量T，用尖括号括起来
{private T first;private T second;//指方法的返回类型以及域和局部变量的类型public Pair() { first = null; second = null; }public Pair(T first, T second) { this.first = first;  this.second = second; }public T getFirst() { return first; }public T getSecond() { return second; }public void setFirst(T newValue) { first = newValue; }public void setSecond(T newValue) { second = newValue; }
}

package pair1;/*** @version 1.01 2012-01-26* @author Cay Horstmann*/
public class PairTest1
{public static void main(String[] args){String[] words = { "Mary", "had", "a", "little", "lamb" };//ArrayAlg调用静态方法minmax()；Pair<String> mm = ArrayAlg.minmax(words);System.out.println("min = " + mm.getFirst());System.out.println("max = " + mm.getSecond());}
}class ArrayAlg
{/*** Gets the minimum and maximum of an array of strings.* @param a an array of strings* @return a pair with the min and max value, or null if a is null or empty*/public static Pair<String> minmax(String[] a)//定义静态泛型方法，将类型变量实例化为String；
   {if (a == null || a.length == 0) return null;//a.length是数组的属性值；String min = a[0];String max = a[0];for (int i = 1; i < a.length; i++){if (min.compareTo(a[i]) > 0) min = a[i];if (max.compareTo(a[i]) < 0) max = a[i];}return new Pair<>(min, max);//调用泛型类对象，返回一个实例化后的类对象；
   }
}

package pair2;/*** @version 1.00 2004-05-10* @author Cay Horstmann*/
public class Pair<T>
{private T first;private T second;public Pair() { first = null; second = null; }public Pair(T first, T second) { this.first = first;  this.second = second; }public T getFirst() { return first; }public T getSecond() { return second; }public void setFirst(T newValue) { first = newValue; }public void setSecond(T newValue) { second = newValue; }
}

package pair2;
//import PairTest1.Pair;
import java.time.*;/*** @version 1.02 2015-06-21* @author Cay Horstmann*/
public class PairTest2
{public static void main(String[] args){LocalDate[] birthdays = { //按ASCII码比较，大写字母比小写字母的ASCII码小;LocalDate.of(1906, 12, 9), // G. HopperLocalDate.of(1815, 12, 10), // A. LovelaceLocalDate.of(1903, 12, 3), // J. von NeumannLocalDate.of(1910, 6, 22), // K. Zuse
         };//ArrayAlg调用静态方法minmax();Pair<LocalDate> mm = ArrayAlg.minmax(birthdays);System.out.println("min = " + mm.getFirst());System.out.println("max = " + mm.getSecond());}
}class ArrayAlg
{/**Gets the minimum and maximum of an array of objects of type T.@param a an array of objects of type T@return a pair with the min and max value, or null if a is null or empty*/public static <T extends Comparable> Pair<T> minmax(T[] a) //泛型变量加了泛型约束的方法;
   {if (a == null || a.length == 0) return null;T min = a[0];T max = a[0];for (int i = 1; i < a.length; i++){if (min.compareTo(a[i]) > 0) min = a[i];if (max.compareTo(a[i]) < 0) max = a[i];}return new Pair<>(min, max);//返回一个实例化泛型Pair类对象；
   }
}

package pair3;/*** @version 1.00 2004-05-10* @author Cay Horstmann*/
public class Pair<T>
{private T first;private T second;public Pair() { first = null; second = null; }public Pair(T first, T second) { this.first = first;  this.second = second; }public T getFirst() { return first; }public T getSecond() { return second; }public void setFirst(T newValue) { first = newValue; }public void setSecond(T newValue) { second = newValue; }
}

package pair3;/*** @version 1.01 2012-01-26* @author Cay Horstmann*/
public class PairTest3
{public static void main(String[] args){Manager ceo = new Manager("Gus Greedy", 800000, 2003, 12, 15);Manager cfo = new Manager("Sid Sneaky", 600000, 2003, 12, 15);Pair<Manager> buddies = new Pair<>(ceo, cfo);      printBuddies(buddies);ceo.setBonus(1000000);cfo.setBonus(500000);Manager[] managers = { ceo, cfo };Pair<Employee> result = new Pair<>();minmaxBonus(managers, result);System.out.println("first: " + result.getFirst().getName() + ", second: " + result.getSecond().getName());maxminBonus(managers, result);System.out.println("first: " + result.getFirst().getName() + ", second: " + result.getSecond().getName());}public static void printBuddies(Pair<? extends Employee> p)//<? extends type>表示带有上界
   {Employee first = p.getFirst();Employee second = p.getSecond();System.out.println(first.getName() + " and " + second.getName() + " are buddies.");}//"?"在这儿是通配符，符号表明参数的类型可以是任何一种类型，它和参数T的含义是有区别的public static void minmaxBonus(Manager[] a, Pair<? super Manager> result)//<? super type>表示带有下界
{if (a.length == 0) return;Manager min = a[0];Manager max = a[0];for (int i = 1; i < a.length; i++){if (min.getBonus() > a[i].getBonus()) min = a[i];if (max.getBonus() < a[i].getBonus()) max = a[i];}result.setFirst(min);result.setSecond(max);}//T表示一种未知类型，而“？”表示任何一种类型public static void maxminBonus(Manager[] a, Pair<? super Manager> result){minmaxBonus(a, result);PairAlg.swapHelper(result); // swapHelper捕获通配符类型
   }
}class PairAlg
{public static boolean hasNulls(Pair<?> p){return p.getFirst() == null || p.getSecond() == null;}public static void swap(Pair<?> p) { swapHelper(p); }public static <T> void swapHelper(Pair<T> p){T t = p.getFirst();p.setFirst(p.getSecond());p.setSecond(t);}
}

package pair3;import java.time.*;public class Employee
{  private String name;private double salary;private LocalDate hireDay;public Employee(String name, double salary, int year, int month, int day){this.name = name;this.salary = salary;hireDay = LocalDate.of(year, month, day);}public String getName(){return name;}public double getSalary(){  return salary;}public LocalDate getHireDay(){  return hireDay;}public void raiseSalary(double byPercent){  double raise = salary * byPercent / 100;salary += raise;}
}

package pair3;public class Manager extends Employee
{  private double bonus;/**@param name the employee's name@param salary the salary@param year the hire year@param month the hire month@param day the hire day*/public Manager(String name, double salary, int year, int month, int day){  super(name, salary, year, month, day);bonus = 0;}public double getSalary(){ double baseSalary = super.getSalary();return baseSalary + bonus;}public void setBonus(double b){  bonus = b;}public double getBonus(){  return bonus;}
}

package fghjg;
import java.util.Random;
import java.util.Scanner;import java.io.FileNotFoundException;import java.io.PrintWriter;public class Main{public static void main(String[] args){yunsuan counter=new yunsuan();//与其它类建立联系PrintWriter out=null;try {out=new PrintWriter("D:/text.txt");//将文件里的内容读入到D盘名叫text的文件中
         }catch(FileNotFoundException e) {System.out.println("文件找不到");e.printStackTrace();}int sum=0;for(int i=0;i<10;i++){int a=new Random().nextInt(100);int b=new Random().nextInt(100);Scanner in=new Scanner(System.in);//in.close();switch((int)(Math.random()*4)){case 0:System.out.println( ""+a+"+"+b+"=");int c1 = in.nextInt();out.println(a+"+"+b+"="+c1);if (c1 == counter.plus(a, b)) {sum += 10;System.out.println("答案正确");}else {System.out.println("答案错误");}break ;case 1:if(a<b){int temp=a;a=b;b=temp;}//为避免减数比被减数大的情况
System.out.println(""+a+"-"+b+"=");/*while((a-b)<0){  b = (int) Math.round(Math.random() * 100);}*/int c2 = in.nextInt();out.println(a+"-"+b+"="+c2);if (c2 == counter.minus(a, b)) {sum += 10;System.out.println("答案正确");}else {System.out.println("答案错误");}break ;case 2:System.out.println(""+a+"*"+b+"=");int c = in.nextInt();out.println(a+"*"+b+"="+c);if (c == counter.multiply(a, b)) {sum += 10;System.out.println("答案正确");}else {System.out.println("答案错误");}break;case 3:while(b==0){  b = (int) Math.round(Math.random() * 100);//满足分母不为0
        }while(a%b!=0){a = (int) Math.round(Math.random() * 100);b = (int) Math.round(Math.random() * 100);}System.out.println(""+a+"/"+b+"=");int c0= in.nextInt();out.println(a+"/"+b+"="+c0);if (c0 == counter.divide(a, b)) {sum += 10;System.out.println("答案正确");}else {System.out.println("答案错误");}break;}}System.out.println("totlescore:"+sum);out.println(sum);out.close();}}

package fghjg;
public class yunsuan <T>{private T a;private T b;public void yunsaun(){a=null;b=null;}public void yunsuan(T a,T b){this.a=a;this.b=b;}public int plus(int a,int b){return a+b;}public int minus(int a,int b){return a-b;}public int multiply(int a,int b){return a*b;}public int divide(int a,int b){if(b!=0  && a%b==0)return a/b;elsereturn 0;}}