cannot read from or write to the files in the local computer? in java code example

Example 1: Write an application that reads the content of the current directory and prints it to the screen. java

package com.vogella.java.files;

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

public class FilesUtil {
    public static String readTextFile(String fileName) throws IOException {
        String content = new String(Files.readAllBytes(Paths.get(fileName)));
        return content;
    }

    public static List<String> readTextFileByLines(String fileName) throws IOException {
        List<String> lines = Files.readAllLines(Paths.get(fileName));
        return lines;
    }

    public static void writeToTextFile(String fileName, String content) throws IOException {
        Files.write(Paths.get(fileName), content.getBytes(), StandardOpenOption.CREATE);
    }

}

Example 2: Write an application that reads the content of the current directory and prints it to the screen. java

package com.vogella.java.files;

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

public class Main {
  public static void main(String[] args) throws IOException {
    String input = FilesUtil.readTextFile("file.txt");
    System.out.println(input);
    FilesUtil.writeToTextFile("copy.txt", input);

    System.out.println(FilesUtil.readTextFile("copy.txt"));

    FilesUtil.readTextFileByLines("file.txt");
    Path path = Paths.get("file.txt");
  }
}