Today we will look into different java read file line by line methods. Sometimes we have to read file line by line to a String, for example calling a method by passing each line as String to process it.
Java Read File line by line
We can read file line by line using different ways. Let’s look at some of them.
Java Read File line by line using BufferedReader
We can use java.io.BufferedReader readLine() method to read file line by line to String. This method returns null when end of file is reached. Below is a simple program showing example for java read file line by line using BufferedReader.
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package com.journaldev.readfileslinebyline; import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; public class ReadFileLineByLineUsingBufferedReader { public static void main(String[] args) { BufferedReader reader; try { reader = new BufferedReader(new FileReader( "/Users/pankaj/Downloads/myfile.txt")); String line = reader.readLine(); while (line != null) { System.out.println(line); // read next line line = reader.readLine(); } reader.close(); } catch (IOException e) { e.printStackTrace(); } } } |
Java Read File line by line using Scanner
We can use Scanner class to open a file and then read its content line by line. Below is the scanner example to read file line by line and print it.
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package com.journaldev.readfileslinebyline; import java.io.File; import java.io.FileNotFoundException; import java.util.Scanner; public class ReadFileLineByLineUsingScanner { public static void main(String[] args) { try { Scanner scanner = new Scanner(new File("/Users/pankaj/Downloads/myfile.txt")); while (scanner.hasNextLine()) { System.out.println(scanner.nextLine()); } scanner.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } } } |
Java Read File line by line using Files
java.nio.file.Files is a utility class that contains various useful methods. Files readAllLines method can be used to read all the file lines into a list of string.
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package com.journaldev.readfileslinebyline; import java.io.IOException; import java.nio.file.Files; import java.nio.file.Paths; import java.util.List; public class ReadFileLineByLineUsingFiles { public static void main(String[] args) { try { List<String> allLines = Files.readAllLines(Paths.get("/Users/pankaj/Downloads/myfile.txt")); for (String line : allLines) { System.out.println(line); } } catch (IOException e) { e.printStackTrace(); } } } |
Java Read File line by line using RandomAccessFile
We can use RandomAccessFile to open a file in read mode and then use its readLine method to read file line by line.
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package com.journaldev.readfileslinebyline; import java.io.IOException; import java.io.RandomAccessFile; public class ReadFileLineByLineUsingRandomAccessFile { public static void main(String[] args) { try { RandomAccessFile file = new RandomAccessFile("/Users/pankaj/Downloads/myfile.txt", "r"); String str; while ((str = file.readLine()) != null) { System.out.println(str); } file.close(); } catch (IOException e) { e.printStackTrace(); } } } |
That’s all for java read file line by line using different methods.
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