狄慧201771010104《面向对象程序设计（java）》第八周学习总结
实验六接口的定义与使用
实验时间 2018-10-18
一、实验目的与要求
(1) 掌握接口定义方法；
(2) 掌握实现接口类的定义要求；
(3) 掌握实现了接口类的使用要求；
(4) 掌握程序回调设计模式；
(5) 掌握Comparator接口用法；
(6) 掌握对象浅层拷贝与深层拷贝方法；
(7) 掌握Lambda表达式语法；
(8) 了解内部类的用途及语法要求。
二、实验内容和步骤
实验1： 导入第6章示例程序，测试程序并进行代码注释。
测试程序1：
l 编辑、编译、调试运行阅读教材214页-215页程序6-1、6-2，理解程序并分析程序运行结果；
l 在程序中相关代码处添加新知识的注释。
l 掌握接口的实现用法；
l 掌握内置接口Compareable的用法。
package interfaces; import java.util.*; /** * This program demonstrates the use of the Comparable interface. * @version 1.30 2004-02-27 * @author Cay Horstmann */ public class EmployeeSortTest { public static void main(String[] args) { Employee[] staff = new Employee[3];//普通数组 staff[0] = new Employee("Harry Hacker", 35000); staff[1] = new Employee("Carl Cracker", 75000); staff[2] = new Employee("Tony Tester", 38000); Arrays.sort(staff);//静态方法sort // print out information about all Employee objects for (Employee e : staff) System.out.println("name=" + e.getName() + ",salary=" + e.getSalary()); } }
package interfaces; public class Employee implements Comparable<Employee>//Employee实现JDK内置接口Comparable { private String name; private double salary; //构造方法 public Employee(String name, double salary) { this.name = name; this.salary = salary; } //访问器 public String getName() { return name; } public double getSalary() { return salary; } //调用方法 public void raiseSalary(double byPercent) { double raise = salary * byPercent / 100; salary += raise; } /** * Compares employees by salary * @param other another Employee object * @return a negative value if this employee has a lower salary than * otherObject, 0 if the salaries are the same, a positive value otherwise */ public int compareTo(Employee other) { return Double.compare(salary, other.salary);//静态Double.compare方法 } }
测试程序2：
l 编辑、编译、调试以下程序，结合程序运行结果理解程序；
|
interface A { double g=9.8; void show( ); } class C implements A { public void show( ) {System.out.println("g="+g);} }
class InterfaceTest { public static void main(String[ ] args) { A a=new C( ); a.show( ); System.out.println("g="+C.g); } } |
public interface A { double g=9.8; void show( ); }
class C implements A { public void show( ) {System.out.println("g="+g);} }
package InterfaceTest; public class InterfaceTest { public static void main(String[ ] args) { A a=new C( ); a.show( ); System.out.println("g="+C.g); } }
测试程序3：
l 在elipse IDE中调试运行教材223页6-3，结合程序运行结果理解程序；
l 26行、36行代码参阅224页，详细内容涉及教材12章。
l 在程序中相关代码处添加新知识的注释。
l 掌握回调程序设计模式；
package timer; /** @version 1.01 2015-05-12 @author Cay Horstmann */ import java.awt.*; import java.awt.event.*; import java.util.*; import javax.swing.*; import javax.swing.Timer; // to resolve conflict with java.util.Timer public class TimerTest { public static void main(String[] args) { ActionListener listener = new TimePrinter(); //实现了ActionListener的类对象 // construct a timer that calls the listener // once every 10 seconds Timer t = new Timer(10000, listener);//定义间隔 t.start(); JOptionPane.showMessageDialog(null, "Quit program?"); System.exit(0); } } class TimePrinter implements ActionListener//内置接口 { public void actionPerformed(ActionEvent event) { System.out.println("At the tone, the time is " + new Date()); Toolkit.getDefaultToolkit().beep(); } }
测试程序4：
l 调试运行教材229页-231页程序6-4、6-5，结合程序运行结果理解程序；
l 在程序中相关代码处添加新知识的注释。
l 掌握对象克隆实现技术；
l 掌握浅拷贝和深拷贝的差别。
package clone; /** * This program demonstrates cloning. * @version 1.10 2002-07-01 * @author Cay Horstmann */ public class CloneTest { public static void main(String[] args) { try { Employee original = new Employee("John Q. Public", 50000); //Employee是一个自定义类 original.setHireDay(2000, 1, 1); Employee copy = original.clone(); copy.raiseSalary(10);//原有对象不会发生变化 copy.setHireDay(2002, 12, 31);//更改器 System.out.println("original=" + original);//字符串连接 System.out.println("copy=" + copy); } catch (CloneNotSupportedException e) { e.printStackTrace(); } } }
实验2： 导入第6章示例程序6-6，学习Lambda表达式用法。
l 调试运行教材233页-234页程序6-6，结合程序运行结果理解程序；
l 在程序中相关代码处添加新知识的注释。
l 将27-29行代码与教材223页程序对比，将27-29行代码与此程序对比，体会Lambda表达式的优点。
package lambda; import java.util.*; import javax.swing.*; import javax.swing.Timer; /** * This program demonstrates the use of lambda expressions. * @version 1.0 2015-05-12 * @author Cay Horstmann */ public class LambdaTest { public static void main(String[] args) { String[] planets = new String[] { "Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune" };//定义数组planets System.out.println(Arrays.toString(planets));//静态方法 System.out.println("Sorted in dictionary order:"); Arrays.sort(planets);//Arrays.sort方法接收实验Lambda类的对象 System.out.println(Arrays.toString(planets)); System.out.println("Sorted by length:"); Arrays.sort(planets, (first, second) -> first.length() - second.length());//Lambda表达式 System.out.println(Arrays.toString(planets)); Timer t = new Timer(1000, event -> System.out.println("The time is " + new Date()));//Lambda表达式 t.start(); // keep program running until user selects "Ok" JOptionPane.showMessageDialog(null, "Quit program?"); System.exit(0); //返回类型 } }
package clone; import java.util.Date; import java.util.GregorianCalendar; public class Employee implements Cloneable { //定义三个私有属性 private String name;//string类在lang包 private double salary; private Date hireDay; public Employee(String name, double salary) { this.name = name; this.salary = salary; hireDay = new Date(); }//构造方法 public Employee clone() throws CloneNotSupportedException { // call Object.clone() Employee cloned = (Employee) super.clone();//强制类型转换 // clone mutable fields cloned.hireDay = (Date) hireDay.clone(); return cloned; } /** * Set the hire day to a given date. * @param year the year of the hire day * @param month the month of the hire day * @param day the day of the hire day */ public void setHireDay(int year, int month, int day) { Date newHireDay = new GregorianCalendar(year, month - 1, day).getTime(); //创建一个实例字段变异的实例 // Example of instance field mutation hireDay.setTime(newHireDay.getTime()); } public void raiseSalary(double byPercent) { double raise = salary * byPercent / 100; salary += raise; }//调用 public String toString() { return "Employee[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay + "]"; } }
注：以下实验课后完成
实验3: 编程练习
l 编制一个程序，将身份证号.txt 中的信息读入到内存中；
l 按姓名字典序输出人员信息；
l 查询最大年龄的人员信息；
l 查询最小年龄人员信息；
l 输入你的年龄，查询身份证号.txt中年龄与你最近人的姓名、身份证号、年龄、性别和出生地；
l 查询人员中是否有你的同乡。
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 Search{ private static ArrayList<Person> Personlist1; public static void main(String[] args) { Personlist1 = new ArrayList<>(); Scanner scanner = new Scanner(System.in); File file = new File("E:\\面向对象程序设计Java\\实验\\实验六\\身份证号.txt"); try { FileInputStream F = new FileInputStream(file); BufferedReader in = new BufferedReader(new InputStreamReader(F)); 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); Personlist1.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("******************************************"); System.out.println("1:按姓名字典顺序输出信息；"); System.out.println("2:查询最大年龄与最小年龄人员信息；"); System.out.println("3：按省份找你的同乡；"); System.out.println("4:输入你的年龄,查询年龄与你最近人的信息；"); System.out.println("5：退出"); System.out.println("******************************************"); int type = scanner.nextInt(); switch (type) { case 1: Collections.sort(Personlist1); System.out.println(Personlist1.toString()); break; case 2: int max=0,min=100;int j,k1 = 0,k2=0; for(int i=1;i<Personlist1.size();i++) { j=Personlist1.get(i).getage(); if(j>max) { max=j; k1=i; } if(j<min) { min=j; k2=i; } } System.out.println("年龄最大："+Personlist1.get(k1)); System.out.println("年龄最小："+Personlist1.get(k2)); break; case 3: System.out.println("place?"); String find = scanner.next(); String place=find.substring(0,3); String place2=find.substring(0,3); for (int i = 0; i <Personlist1.size(); i++) { if(Personlist1.get(i).getbirthplace().substring(1,4).equals(place)) { System.out.println("你的同乡："+Personlist1.get(i)); } } break; case 4: System.out.println("年龄："); int yourage = scanner.nextInt(); int close=ageclose(yourage); int d_value=yourage-Personlist1.get(close).getage(); System.out.println(""+Personlist1.get(close)); break; case 5: isTrue = false; System.out.println("再见!"); break; default: System.out.println("输入有误"); } } } public static int ageclose(int age) { int m=0; int max=53; int d_value=0; int k=0; for (int i = 0; i < Personlist1.size(); i++) { d_value=Personlist1.get(i).getage()-age; if(d_value<0) d_value=-d_value; if (d_value<max) { max=d_value; 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"; } }
实验4：内部类语法验证实验
实验程序1：
l 编辑、调试运行教材246页-247页程序6-7，结合程序运行结果理解程序；
l 了解内部类的基本用法。
package innerClass; import java.awt.*; import java.awt.event.*; import java.util.*; import javax.swing.*; import javax.swing.Timer; /** * This program demonstrates the use of inner classes. * @version 1.11 2015-05-12 * @author Cay Horstmann */ public class InnerClassTest { public static void main(String[] args) { TalkingClock clock = new TalkingClock(1000, true);//实现了TalkingClock的类对象 clock.start(); // keep program running until user selects "Ok" JOptionPane.showMessageDialog(null, "Quit program?"); System.exit(0);// } } /** * A clock that prints the time in regular intervals. */ class TalkingClock { //声明属性 private int interval; private boolean beep; /** * Constructs a talking clock * @param interval the interval between messages (in milliseconds) * @param beep true if the clock should beep */ public TalkingClock(int interval, boolean beep) { this.interval = interval; this.beep = beep; }//构造方法 /** * Starts the clock. */ public void start() { ActionListener listener = new TimePrinter(); Timer t = new Timer(interval, listener); t.start(); } public class TimePrinter implements ActionListener//实现ActionListener的公共类TimePrinter { public void actionPerformed(ActionEvent event) { System.out.println("At the tone, the time is " + new Date()); if (beep) Toolkit.getDefaultToolkit().beep(); } } }
实验程序2：
l 编辑、调试运行教材254页程序6-8，结合程序运行结果理解程序；
l 了解匿名内部类的用法。
package anonymousInnerClass; import java.awt.*; import java.awt.event.*; import java.util.*; import javax.swing.*; import javax.swing.Timer; /** * This program demonstrates anonymous inner classes. * @version 1.11 2015-05-12 * @author Cay Horstmann */ public class AnonymousInnerClassTest { public static void main(String[] args) { TalkingClock clock = new TalkingClock();//TalkingClock类声明为私有的 clock.start(1000, true); // keep program running until user selects "Ok" JOptionPane.showMessageDialog(null, "Quit program?"); System.exit(0); } } /** * A clock that prints the time in regular intervals. */ class TalkingClock { /** * Starts the clock. * @param interval the interval between messages (in milliseconds) * @param beep true if the clock should beep */ public void start(int interval, boolean beep) { ActionListener listener = new ActionListener() { public void actionPerformed(ActionEvent event) { System.out.println("At the tone, the time is " + new Date()); if (beep) Toolkit.getDefaultToolkit().beep(); //外围类引用. } }; Timer t = new Timer(interval, listener); t.start(); } }
实验程序3：
l 在elipse IDE中调试运行教材257页-258页程序6-9，结合程序运行结果理解程序；
l 了解静态内部类的用法。
package staticInnerClass; /** * This program demonstrates the use of static inner classes. * @version 1.02 2015-05-12 * @author Cay Horstmann */ public class StaticInnerClassTest { public static void main(String[] args) { double[] d = new double[20]; for (int i = 0; i < d.length; i++) d[i] = 100 * Math.random();//算法 ArrayAlg.Pair p = ArrayAlg.minmax(d); System.out.println("min = " + p.getFirst()); System.out.println("max = " + p.getSecond()); }//访问器 } class ArrayAlg { /** * A pair of floating-point numbers */ public static class Pair { //声明私有属性 private double first; private double second; /** * Constructs a pair from two floating-point numbers * @param f the first number * @param s the second number */ public Pair(double f, double s) { first = f; second = s; } /** * Returns the first number of the pair * @return the first number */ public double getFirst() { return first; } // 访问器 /** * Returns the second number of the pair * @return the second number */ public double getSecond() { return second; } } /** * Computes both the minimum and the maximum of an array * @param values an array of floating-point numbers * @return a pair whose first element is the minimum and whose second element * is the maximum */ public static Pair minmax(double[] values) { double min = Double.POSITIVE_INFINITY; double max = Double.NEGATIVE_INFINITY;//变量 for (double v : values) { if (min > v) min = v; if (max < v) max = v; } return new Pair(min, max); } }
三、实验总结：
在这次实验中，我了解并学习了接口的实现用法、内置接口Compareable的用法、对象克隆实现技术以及Lambda表达式。通过自学，我接触了内部类、匿名内部类以及静态内部类的用法。在编程和编译过程中遇到的一些难题和出现的一些问题，我通过查阅资料、上网查找和同学讨论得以解决。
