[Java] File system operation

File system operation

• Files class
• Create a Path object with the getPath method
• Get the current filesystem with the FileSystems.getDefault method

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

public class Main {
  public static void main(String[] args) {
    try {
      //Get current file system
      var fs = FileSystems.getDefault();
      var path1 = fs.getPath("./sample.txt");
      //File existence confirmation
      System.out.println(Files.exists(path1));       //true
      //Is the file readable?
      System.out.println(Files.isReadable(path1));   //true
      //Is the file writable?
      System.out.println(Files.isWritable(path1));   //true
      //Is the file executable?
      System.out.println(Files.isExecutable(path1)); //true
      //file size
      System.out.println(Files.size(path1));
      //File copy
      var path2 = Files.copy(path1, fs.getPath("./copy.txt"),
        StandardCopyOption.REPLACE_EXISTING);
      //Move file
      Files.move(path2, fs.getPath("./sub/copy.txt"),
        StandardCopyOption.REPLACE_EXISTING);
    　//File name change
      var path3 = Files.move(path1, fs.getPath("./sub/rename.txt"),
        StandardCopyOption.REPLACE_EXISTING);
      //File deletion
      Files.delete(path3);
      //Delete if the file exists (no exception occurs)
      Files.deleteIfExists(path3);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

Folder operation

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;

public class Main {
  public static void main(String[] args) {
    try {
      var fs = FileSystems.getDefault();
      var dir1 = fs.getPath("./playground");
      var dir2 = fs.getPath("./data");
      //Create folder
      Files.createDirectories(dir1);
      //Does the folder exist?
      System.out.println(Files.exists(dir1)); //true
      //Is it a folder?
      System.out.println(Files.isDirectory(dir1)); //true
      //Subfile under dir2/Get folder stream
      var s = Files.list(dir2);
      //.Get filename ending in log
      s.filter(v -> v.getFileName().toString().endsWith(".log")).
        forEach(System.out::println); //./data/test.log
      //Folder copy
      var dir3 = Files.copy(dir1, fs.getPath("./data"),
        StandardCopyOption.REPLACE_EXISTING);
      //Move folder
      Files.move(dir3, fs.getPath("./data"),
          StandardCopyOption.REPLACE_EXISTING);
      //Delete folder
      Files.delete(fs.getPath("./data/sub"));
      //Delete only when the folder exists
      Files.deleteIfExists(fs.getPath("./data/sub"));
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}