java - 反转txt文件的行顺序

Question

我需要导入一个文本文件并导出一个文本文件，其中行的顺序相反

输入示例:

abc

123

First line

预期输出:

First line 

123

abc

这就是我到目前为止所拥有的。它颠倒了行，但不颠倒行顺序。任何帮助将不胜感激

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class reversetext {

    public static void main(String[] args) throws IOException {
        try {

            File sourceFile = new File("in.txt");//input File Path
            File outFile = new File("out.txt");//out put file path

            Scanner content = new Scanner(sourceFile);
            PrintWriter pwriter = new PrintWriter(outFile);

            while(content.hasNextLine()) {
                String s = content.nextLine();
                StringBuffer buffer = new StringBuffer(s);
                buffer = buffer.reverse();
                String rs = buffer.toString();
                pwriter.println(rs);
            }
            content.close();    
            pwriter.close();
        }
        catch(Exception e) {
              System.out.println("Something went wrong");
        }
    }
}

Answer 1

我能想到的最简单的答案是，使用 Java 7+ 并且不依赖像 Stack 这样已弃用的构建 block :

private static final String INPUT_FILE = "input.txt";
private static final String OUTPUT_FILE = "output.txt";
private static final String USER_HOME = System.getProperty("user.home");

public static void main(String... args) {
    try {
        try (PrintWriter writer = new PrintWriter(Files.newBufferedWriter(Paths.get(USER_HOME + "/" + OUTPUT_FILE)))) {
            Files
             .lines(Paths.get(USER_HOME + "/" + INPUT_FILE))
             .collect(Collectors.toCollection(LinkedList::new))
             .descendingIterator()
             .forEachRemaining(writer::println);
        }
    } catch (Exception e) {
        e.printStackTrace();
        System.exit(1);
    }

}

只需读入输入文件并获取 String 中的内容流 (Files#lines)。然后使用降序迭代器将它们收集到 LinkedList 中，循环遍历它们并将它们写到输出文件中。