一笔试小题---文件读写操作（希望对刚毕业找工作的朋友有所帮助）

class Student implements Comparable
{
 int age;
 String name; 
 
 public Student(int age, String name)
 {
  this.age  = age;
  this.name = name;  
 }
 public int compareTo(Object o)
 {
  Student s = (Student)o;
  return age > s.age ? 1:(age == s.age ? 0 : -1);
 }
}

 这种思路是很好的，也能很好解决后面数字重复的问题。而且这种完全用了面向对象的思想。

 代码如下：student.java封装文件中的对象， Test.java为测试类

public class Student implements Comparable<Student> {
	private String name;
	private int orderNumber;

	public Student() {

	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getOrderNumber() {
		return orderNumber;
	}

	public void setOrderNumber(int orderNumber) {
		this.orderNumber = orderNumber;
	}

	public int compareTo(Student o) {
		// return this.orderNumber>o.orderNumber?1:(this.orderNumber==o.orderNumber?0:-1);//小到大排序
   	return o.orderNumber > this.orderNumber ? 1
				: (o.orderNumber == this.orderNumber ? 0 : -1);// 大到小排序

	}
}

Test.java

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Test {
	public static void main(String[] ars){		
		Test test = new Test();
		test.sortFile("d:/source.txt", "d:/dest.txt");		
	}

	public void sortFile(String sourceFile, String destFile) {
		BufferedReader bReader = null;
		PrintWriter pWriter = null;
		try {
			bReader = new BufferedReader(new InputStreamReader(
					new FileInputStream(sourceFile)));
			String keyString = bReader.readLine();		
			List<Student> list = new ArrayList<Student>();
			while (keyString != null) {
				String[] ar = keyString.split(" ");
				Student student = new Student();
				student.setName(ar[0]);
				student.setOrderNumber(Integer.parseInt(ar[1]));			
				list.add(student);
				keyString = bReader.readLine();
			}
			System.out.println("读取文件成功...");
			Object[] objects = list.toArray();
			Arrays.sort(objects);
			pWriter = new PrintWriter(new FileOutputStream(destFile));			
			for (Object o:objects) {
				Student student = (Student) o;
				pWriter.println(new StringBuilder(student.getName())
						.append(" ").append(student.getOrderNumber())
						.toString());
			}
			pWriter.flush();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (bReader != null) {
				try {
					bReader.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			if (pWriter != null) {
				pWriter.close();
			}
		}
		System.out.println("保存文件成功....");
	}
}