Read data from a text file using Java

Question

I need to read a text file line by line using Java. I use available() method of FileInputStream to check and loop over the file. But while reading,

Answer 1

Yes, buffering should be used for better performance. Use BufferedReader OR byte[] to store your temp data.

thanks.

Answer 2

If you want to read line-by-line, use a BufferedReader. It has a readLine() method which returns the line as a String, or null if the end of the file has been reached. So you can do something like:

BufferedReader reader = new BufferedReader(new InputStreamReader(fis));
String line;
while ((line = reader.readLine()) != null) {
 // Do something with line
}

(Note that this code doesn't handle exceptions or close the stream, etc)

Answer 3

How about using Scanner? I think using Scanner is easier

     private static void readFile(String fileName) {
       try {
         File file = new File(fileName);
         Scanner scanner = new Scanner(file);
         while (scanner.hasNextLine()) {
           System.out.println(scanner.nextLine());
         }
         scanner.close();
       } catch (FileNotFoundException e) {
         e.printStackTrace();
       }
     }

Read more about Java IO here

Answer 4

public class ReadFileUsingFileInputStream {

/**
* @param args
*/
static int ch;

public static void main(String[] args) {
    File file = new File("C://text.txt");
    StringBuffer stringBuffer = new StringBuffer("");
    try {
        FileInputStream fileInputStream = new FileInputStream(file);
        try {
            while((ch = fileInputStream.read())!= -1){
                stringBuffer.append((char)ch);  
            }
        }
        catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    System.out.println("File contents :");
    System.out.println(stringBuffer);
    }
}

Answer 5

public class FilesStrings {

public static void main(String[] args) throws FileNotFoundException, IOException {
    FileInputStream fis = new FileInputStream("input.txt");
    InputStreamReader input = new InputStreamReader(fis);
    BufferedReader br = new BufferedReader(input);
    String data;
    String result = new String();

    while ((data = br.readLine()) != null) {
        result = result.concat(data + " ");
    }

    System.out.println(result);

Answer 6

In Java 8 you could easily turn your text file into a List of Strings with streams by using Files.lines and collect:

private List<String> loadFile() {
    URI uri = null;
    try {
        uri = ClassLoader.getSystemResource("example.txt").toURI();
    } catch (URISyntaxException e) {
        LOGGER.error("Failed to load file.", e);
    }
    List<String> list = null;
    try (Stream<String> lines = Files.lines(Paths.get(uri))) {
        list = lines.collect(Collectors.toList());
    } catch (IOException e) {
        LOGGER.error("Failed to load file.", e);
    }
    return list;
}