软件工程文档编制

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醒侈仇
7 years ago
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1 实训抽象类一实训目标掌握抽象类的定义使用掌握运行时多态二知识点抽象类的语法格式如下 : public abstract class ClassName abstract void 方法名称 ( 参数 ); // 非抽象方法的实现代码在使用抽象类时需要注意如下几点 : 1 抽象类不能被实例化, 实例化的工作应该交由它的子类来完成 2 抽象方法必须由子类来进行重写 3 只要包含一个抽象方法的抽象类, 该方法必须要定义成抽象类, 不管是否还包含有其他方法 4 抽象类中可以包含具体的方法, 当然也可以不包含抽象方法 5 子类中的抽象方法不能与父类的抽象方法同名 6 abstract 不能与 final 并列修饰同一个类 7 abstract 不能与 private static final 或 native 并列修饰同一个方法 @qq.com 第 1 页, 共 9 页

2 三案例编写一个 java 抽象类, 源代码如下 : public abstract class Employee private String name; private String address; private int number; public Employee(String name, String address, int number) System.out.println("Constructing an Employee"); this.name = name; this.address = address; this.number = number; public double computepay() System.out.println("Inside Employee computepay"); return 0.0; public void mailcheck() System.out.println("Mailing a check to " + this.name + " " + this.address); public String tostring() return name + " " + address + " " + number; public String getname() return name; public String getaddress() return address; @qq.com 第 2 页, 共 9 页

3 public void setaddress(string newaddress) address = newaddress; public int getnumber() return number; 继承 Employee 类的源代码如下 : public class Salary extends Employee private double salary; //Annual salary public Salary(String name, String address, int number, double salary) super(name, address, number); setsalary(salary); public void mailcheck() System.out.println("Within mailcheck of Salary class "); System.out.println("Mailing check to " + getname() + " with salary " + salary); public double getsalary() return salary; public void setsalary(double newsalary) if(newsalary >= 0.0) salary = newsalary; public double computepay() System.out.println("Computing salary pay for " + getname()); @qq.com 第 3 页, 共 9 页

4 return salary/52; 不能实例化一个 Employee 类的对象, 但是如果我们实例化一个 Salary 类对象, 该对象将从 Employee 类继承 7 个成员方法, 且通过该方法可以设置或获取三个成员变量 public class SalaryTest public static void main(string [] args) Salary objsalary = new Salary("Mohd Mohtashim", "Ambehta, UP", 3, ); Employee objemployee = new Salary("John Adams", "Boston, MA", 2, ); System.out.println("Call mailcheck using Salary reference "); objsalary.mailcheck(); System.out.println("\nCall mailcheck using Employee reference "); objemployee.mailcheck(); 编写一个 java 程序, 源代码如下 : public abstract class Shapes public int x, y; public int width, height; public Shapes(int x, int y, int width, int height) this.x = x; this.y = y; this.width = width; this.height = height; abstract double getarea(); abstract double getperimeter(); @qq.com 第 4 页, 共 9 页

5 public class Circle extends Shapes public double r; public double getarea() return (r * r * Math.PI); public double getperimeter() return (2 * Math.PI * r); public Circle(int x, int y, int width, int heigh) super(x, y, width, heigh); r = (double) width / 2.0; public class Square extends Shapes public double getarea() return (width * height); public double getperimeter() return (2 * width + 2 * height); public Square(int x, int y, int width, int height) super(x, y, width, height); public class Triangle extends Shapes public double c; public double getarea() return (0.5 * width * height); public double getperimeter() return (width + height + c); @qq.com 第 5 页, 共 9 页

6 public Triangle(int x, int y, int base, int height) super(x, y, base, height); c = Math.sqrt(width * width + height * height); import java.applet.applet; import java.awt.graphics; public class Test extends Applet Square Box = new Square(5, 15, 25, 25); Triangle tri = new Triangle(5, 50, 8, 4); Circle Oval = new Circle(5, 90, 25, 25); public void paint(graphics g) g.drawrect(box.x, Box.y, Box.width, Box.height); g.drawstring("box Area:" + Box.getArea(), 50, 35); g.drawstring("box Perimeter:" + Box.getPerimeter(), 50, 55); g.drawstring("tri Area:" + tri.getarea(), 50, 75); g.drawstring("tri Perimeter:" + tri.getperimeter(), 50, 95); g.drawoval(oval.x, Oval.y, Oval.width, Oval.height); g.drawstring("oval Area:" + Oval.getArea(), 50, 115); 编写一个 java 程序, 实现三种不同事物的行为, 具体要求如下 : 机器人 : 充电, 工作 ; 人 : 吃饭, 工作, 睡觉 ; 猪 : 进食, 睡觉抽象行为类源代码如下 : public abstract class Action public static final int EAT = 1; public static final int SLEEP = 3; public static final int WORK = 5; public abstract void eat(); public abstract void sleep(); public abstract void work(); @qq.com 第 6 页, 共 9 页

7 public void commond(int flags) switch(flags) case EAT: this.eat(); case SLEEP: this.sleep(); case WORK: this.work(); case EAT + SLEEP: this.eat(); this.sleep(); case SLEEP + WORK: this.sleep(); this.work(); default: 机器人类源代码如下 : public class Robot extends Action public void eat() System.out.println(" 机器人充电 "); public void sleep() public void work() System.out.println(" 机器人工作 "); @qq.com 第 7 页, 共 9 页

8 人类的源代码如下 : public class Human extends Action public void eat() System.out.println(" 人吃饭 "); public void sleep() System.out.println(" 人睡觉 "); public void work() System.out.println(" 人工作 "); 猪类源代码如下 : public class Pig extends Action public void eat() System.out.println(" 猪进食 "); public void sleep() System.out.println(" 猪睡觉 "); public void work() 测试类代码如下 : public class AbstractTest @qq.com 第 8 页, 共 9 页

9 public static void main(string[] args) fun(new Robot()); fun(new Human()); fun(new Pig()); public static void fun(action act) act.commond(action.eat); act.commond(action.sleep); act.commond(action.work); 第 9 页, 共 9 页

OOP with Java 通知 Project 4: 4 月 19 日晚 9 点

OOP with Java Yuanbin Wu cs@ecnu OOP with Java 通知 Project 4: 4 月 19 日晚 9 点复习类的复用组合 (composition): has-a 关系 class MyType { public int i; public double d; public char c; public void set(double x) { d