Java –如何将文件读入列表？

谁践踏了优雅 2023-02-15 05:18 48阅读 0赞

在Java中，几乎没有办法将文件逐行读取到`List`

1. Java 8流

List<String> result;
    	try (Stream<String> lines = Files.lines(Paths.get(fileName))) {
    		result = lines.collect(Collectors.toList());
    	}

2. Java 7

Files.readAllLines(new File(fileName).toPath(), Charset.defaultCharset());

3.经典的BufferedReader示例。

List<String> result = new ArrayList<>();
    	BufferedReader br = null;
    
    	try {
    
    		br = new BufferedReader(new FileReader(fileName));
    
    		String line;
    		while ((line = br.readLine()) != null) {
    			result.add(line);
    		}
    
    	} catch (IOException e) {
    		e.printStackTrace();
    	} finally {
    		if (br != null) {
    			br.close();
    		}
    	}

## 1.文件->列表 ##

1.1虚拟文件

d:\\\\server.log

a
    b
    c
    d
    1
    2
    3

1.2将文件读入`List`

JavaExample.java

package com.mkyong.example;
    
    import java.io.BufferedReader;
    import java.io.File;
    import java.io.FileReader;
    import java.io.IOException;
    import java.nio.charset.Charset;
    import java.nio.file.Files;
    import java.nio.file.Paths;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.stream.Collectors;
    import java.util.stream.Stream;
    
    public class JavaExample {
    
        public static void main(String[] args) {
    
            String filename = "d:\\server.log";
    
            try {
                List list = readByJavaClassic(filename);
                list.forEach(System.out::println);
            } catch (IOException e) {
                e.printStackTrace();
            }
    
    
        }
    
        private static List readByJava8(String fileName) throws IOException {
            List<String> result;
            try (Stream<String> lines = Files.lines(Paths.get(fileName))) {
                result = lines.collect(Collectors.toList());
            }
            return result;
    
        }
    
        private static List readByJava7(String fileName) throws IOException {
            return Files.readAllLines(new File(fileName).toPath(), Charset.defaultCharset());
        }
    
        private static List readByJavaClassic(String fileName) throws IOException {
    
            List<String> result = new ArrayList<>();
            BufferedReader br = null;
    
            try {
    
                br = new BufferedReader(new FileReader(fileName));
    
                String line;
                while ((line = br.readLine()) != null) {
                    result.add(line);
                }
    
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (br != null) {
                    br.close();
                }
            }
    
            return result;
        }
    
    }

输出量

a
    b
    c
    d
    1
    2
    3

## 参考文献 ##

1.  [Java 8 Stream –逐行读取文件][Java 8 Stream]

标签： [java][] [读取文件][Link 1] [流][Link 2]

> 翻译自: [https://mkyong.com/java/java-how-to-read-a-file-into-a-list/][https_mkyong.com_java_java-how-to-read-a-file-into-a-list]

[Java 8 Stream]: https://www.mkyong.com/java8/java-8-stream-read-a-file-line-by-line/
[java]: https://mkyong.com/tag/java/
[Link 1]: https://mkyong.com/tag/read-file/
[Link 2]: https://mkyong.com/tag/stream/
[https_mkyong.com_java_java-how-to-read-a-file-into-a-list]: https://mkyong.com/java/java-how-to-read-a-file-into-a-list/