Reading Files

Read all lines in a file into a List

You can read the lines as List of Strings (Each line as a String) with following code.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;

class FilesHandling {
	public static void main(String[] args) {
		try {
			List<String> lines = Files.readAllLines(Paths.get("/path/to/file.txt"));
			int lineNum = 1;
			for (String line : lines) {
				System.out.println("Line No:" + lineNum + " Content:" + line);
				lineNum++;
			}
		} catch (IOException e) {
			// looks like the file not found with given path
			e.printStackTrace();
		}
	}
}

File content into String

You can read the complete file content into a String with the following code

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;

class FilesHandling {
	public static void main(String[] args) {
		try {
			String fileContent = new String(Files.readAllBytes(Paths.get("/path/to/file.txt")));
			System.out.println("File Content is:" + fileContent);
		} catch (IOException e) {
			// looks like the file not found with given path
			e.printStackTrace();
		}
	}
}

Writing Files

You can write content into a File using following code.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

class FilesHandling {
	public static void main(String[] args) {
		try {
			String contentTobeWritten = "This is the new content you will see in file";
			Files.write(Paths.get("/path/to/file"), contentTobeWritten.getBytes(), StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
		} catch (IOException e) {
			// looks like the file not found with given path
			e.printStackTrace();
		}
	}
}