例1.1 TextFileTest

package SectionIO;
import java.io.*;
import java.util.*;
public class TextFileTest {
	public static void main(String[] args) {
		Employee[] staff=new Employee[3];
		staff[0]=new Employee("Carl Hacker",75000,1987,12,15);
		staff[1]=new Employee("Harry Hacker",5000,1989,10,1);
		staff[2]=new Employee("Tony Tester",40000,1990,3,15);
		try{
			//save all employee records to the file employee.dat
			PrintWriter out = new PrintWriter("employee.dat");
			writeData(staff,out);
			out.close();
			//retrieve all records into a new array
			Scanner in = new Scanner(new FileReader("employee.dat"));
			Employee[] newStaff=readData(in);
			in.close();
			//print the newly read employee records
			for(Employee e:newStaff){
				System.out.println(e);
			}
		}catch(IOException exception){
			exception.printStackTrace();
		}
	}
	/**
	 * Writes all employees in an array to a print writer
	 * @param employees an array of employees
	 * @param out a print writer
	 */
	private static void writeData(Employee[] employees,PrintWriter out)throws IOException{
		//write number of employees
		out.println(employees.length);
		for(Employee e :employees){
			e.writeData(out);
		}
	}
	/**
	 * Reads an array of employees from a scanner
	 * @param in the scanner
	 * @return  the array of employees
	 */
	private static Employee[] readData(Scanner in){
		//retrieve the array size
		int n=in.nextInt();
		in.nextLine();
		Employee[] employees=new Employee[n];
		for(int i=0;i<n;i++){
			employees[i]=new Employee();
			employees[i].readData(in);
		}
		return employees;
	}
}
class Employee{
	public Employee(){
		
	}
	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();
	}
	public String getName(){
		return name;
	}
	public double getSalary(){
		return salary;
	}
	public Date getHireDay(){
		return hireDay;
	}
	public void raseSalary(double byPercent){
		double raise=salary * byPercent/100;
		salary+=raise;
	}
	public String toString(){
		return getClass().getName()+"[name="+name+",salary="+salary+",hireDay="+hireDay+"]";
	}
	/**
	 * Writes employee data to a print writer
	 * @param out the print writer
	 */
	public void writeData(PrintWriter out){
		GregorianCalendar calendar = new GregorianCalendar();
		calendar.setTime(hireDay);
		out.println(name+"|"+salary+"|"+calendar.get(Calendar.YEAR)+"|"+(calendar.get(Calendar.MONTH)+1)+"|"+calendar.get(Calendar.DAY_OF_MONTH));
	}
	/**
	 * Reads employee data from a buffered reader
	 * @param in the scanner
	 */
	public void readData(Scanner in){
		String line = in.nextLine();
		String[] tokens=line.split("\\|");
		name = tokens[0];
		salary=Double.parseDouble(tokens[1]);
		int y=Integer.parseInt(tokens[2]);
		int m=Integer.parseInt(tokens[3]);
		int d=Integer.parseInt(tokens[4]);
		GregorianCalendar calendar=new GregorianCalendar(y,m-1,d);
		hireDay=calendar.getTime();
	}
	private String name;
	private double salary;
	private Date hireDay;
}