java练习题

键盘录入一个文件路径，将该文件反转
反转：第一行变成最后一行，第二行变成倒数第二行

package day19;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class HomeWork2 {
	public static void main(String[] args) throws Exception {
		File f=getFile();
		BufferedReader br=new BufferedReader(new FileReader(f));
		ArrayList<String>list = new ArrayList();
		String line=null;
		while((line=br.readLine())!=null) {
			list.add(line);
		}
		br.close();
		Collections.reverse(list);
		BufferedWriter bw=new BufferedWriter(new FileWriter("E:\\abc.reverse.txt"));
//		for(int i=0;i<list.size();i++) {
//			bw.write(list.get(i));
//			bw.newLine();
//		}
		for (String str : list) {
			bw.write(str);
			bw.newLine();
		}
		bw.flush();
		bw.close();
	}
	private static File getFile() {
		Scanner sc = new Scanner(System.in);
		while(true) {
			String str=sc.nextLine();
			File f=new File(str);
			if(!(f.isFile())) {
				System.out.println("请重新输入");
			}else {
				return f;
			}
		}
			
	}
}