abstracttest.java

编程之道--java程序设计入门源代码

/**
 * 通过本程序的测试，主要学习抽象类及子类，抽象方法的实现
 * 动态绑定，多态
 */
 
import java.text.NumberFormat;

public class AbstractTest
{
	public static void main(String[] args)
	{
		Person[] p = new Person[2];
		p[0] = new Worker("Jack", 1000);
		p[1] = new Student("Tom", "Computer");
		
		for(int i = 0; i < p.length; i++)
		{
			Person people = p[i];
			System.out.println(people.getDescription());
		}
	}
}

/**
 * 抽象类
 */
abstract class Person
{
	private String strName;

	public Person(String strName)
	{
		this.strName = strName;
	}

	public String getName()
	{
		return strName;
	}

	//抽象方法，返回人的描述
	public abstract String getDescription();
}

/**
 * 工人类，扩展了抽象类，并实现了抽象方法
 */
class Worker extends Person
{
	private double salary;
	
	public Worker(String strName, double s)
	{
		super(strName);
		salary = s;
	}
	
	public String getDescription()
	{
		NumberFormat formate = NumberFormat.getCurrencyInstance();
		return "the worker with a salary of " + formate.format(salary);
	}
}

/**
 * 学生类，扩展了抽象类，实现了抽象方法
 */
class Student extends Person
{
	private String strMajor;
	
	public Student(String strName, String strMajor)
	{
		super(strName);
		this.strMajor = strMajor;
	}
	
	public String getDescription()
	{
		return "the student majoring in " + strMajor;
	}
}