Object（所有类的超类）一些有用的方法讲解与实例演示

/**
*员工类
*/
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Objects;
public class Employee
{
	/**
	*@param name 员工姓名
	*@param salary 员工工资
	*@param hireDate 雇用日期
	*/
	private String name;
	private double salary;
	private Date hireDay;
	/**
	*构造方法 初始化员工类的字段
	*/
	public Employee(String n,double s,int year,int month,int day)
	{
		name=n;
		salary=s;
		GregorianCalendar calendar=new GregorianCalendar(year,month-1,day);
		hireDay=calendar.getTime();
	}
	/**
	*私有字段访问器
	*/
	public String getDate()
	{
		return name;
	}
	public double getSalary()
	{
		return salary;
	}
	public Date getHireDay()
	{
		return hireDay;
	}
	/**
	*涨工资的方法
	*/
	public void raiseSalary(double byPercent)
	{
		double raise=salary*byPercent/100;
		salary+=raise; 
	}
	/**
	*重写euqals方法、hashCode方法和toString方法
	*/
	@Override
	public boolean equals(Object obj)
	{
		if(this==obj)	return true;
		if(obj==null)	return false;
		if(getClass()!=obj.getClass())	return false;
		Employee other=(Employee)obj;
		return Objects.equals(name,other.name)&&salary==other.salary&&Objects.equals(hireDay,other.hireDay);
	}
	@Override
	public int hashCode()
	{
		return Objects.hash(name,salary,hireDay);
	}
	@Override
	public String toString()
	{
		return "\t"+getClass().getName()+"\t员工姓名:\t"+name+"\t员工工资:\t"+salary+"\t雇用日期:\t"+hireDay;
	}
}

/**
*经理类 增加了奖金字段
*/
public class Manager extends Employee
{
	private double bonus;
	public Manager(String n,double s,int year,int month,int day)
	{
		super(n,s,year,month,day);
		bonus=0;
	}
	//设置奖金的方法
	public void setBonus(double b)
	{
		bonus=b;
	}
	/**
	*重写Employee的getSalary、equals和方法
	**/
	@Override
	public double getSalary()
	{
		double base=super.getSalary();
		return base+bonus;
	}
	@Override
	public boolean equals(Object obj)
	{
		if(!super.equals(obj))	return false;
		Manager other=(Manager)obj;
		return other.bonus==bonus;
	}
	@Override
	public String toString()
	{
		return super.toString()+"\t经理奖金:\t"+bonus;
	}
}

//测试类
/**
*@author lijtaos@sina.com
*@version 1.0 2015-04-17
**/
public class Test
{
	public static void main(String[] args)
	{
		Employee tom=new Employee("Tom",7500,2010,3,15);
		Employee tom1=tom;
		Employee tom2=new Employee("Tom",7500,2010,3,15);
		tom1.raiseSalary(15);
		Manager bob=new Manager("Bob",10000,2010,3,15);
		bob.raiseSalary(10);
		bob.setBonus(25000);
		System.out.println("tom==tom1:\t"+(tom.equals(tom1)));
		System.out.println("tom==tom2:\t"+(tom.equals(tom2)));
		System.out.println("bob=======\t"+bob);
		System.out.println("tom=======\t"+tom);
		System.out.println("tom1======\t"+tom1);
		System.out.println("tom2======\t"+tom2);
	}
}