Introduction

• The File class in Java is used to represent files and directories in the file system.
• It allows you to create, delete, check and manage files and directories, but it does not handle file content directly.
• The File class is present in the java.io package.
• Syntax:

  public class File implements Serializable, Comparable
  {
      // constructors and methods
  }
  

Important Methods of File Class:

• Below are some common and mostly used methods of File class with examples:

File file = new File("example.txt");
if(file.createNewFile()){
    System.out.println("File created");
}else{
    System.out.println("File already exists");
}

File file = new File("example.txt");
System.out.println(file.exists());

File file = new File("example.txt");
if(file.delete()){
    System.out.println("File deleted");
}else{
    System.out.println("Failed to delete");
}

File file = new File("example.txt");
System.out.println(file.getName());

File file = new File("example.txt");
System.out.println(file.getAbsolutePath());

File file = new File("example.txt");
System.out.println(file.isFile());

File dir = new File("myFolder");
System.out.println(dir.isDirectory());

File dir = new File("myFolder");
if(dir.mkdir()){
    System.out.println("Directory created");
}else{
    System.out.println("Failed to create directory");
}

File dir = new File("myFolder");
String[] contents = dir.list();
for(String name : contents){
    System.out.println(name);
}

Example:

• import java.io.File;
  import java.io.IOException;
  
  public class FileExample
  {
      public static void main(String[] args)
      {
          try
          {
              File file = new File("example.txt");
  
              // Create a new file
              if(file.createNewFile())
              {
                  System.out.println("File created successfully.");
              }
              else
              {
                  System.out.println("File already exists.");
              }
  
              // Check if file exists
              if(file.exists())
              {
                  System.out.println("File exists at: " + file.getAbsolutePath());
              }
  
              // Delete the file
              if(file.delete())
              {
                  System.out.println("File deleted successfully.");
              }
              else
              {
                  System.out.println("Failed to delete file.");
              }
  
          }
          catch (IOException e)
          {
              System.out.println("An error occurred: " + e.getMessage());
          }
      }
  }

  Output:

  File created successfully.
  File exists at: C:\Users\Deepak\example.txt
  File deleted successfully.

Example:

1. The File class represents files or directories, but it does not store content. Use streams or readers/writers for reading/writing data.
2. File paths can be relative or absolute. Relative paths are resolved from the current working directory.
3. Creating a file or directory may fail due to permissions or if the parent directory doesn't exist.
4. Deleting a directory will only succeed if the directory is empty.
5. Always handle IOException when using methods like createNewFile() or accessing file paths.
6. Use mkdirs() if you want to create nested directories along with missing parent directories.
7. File operations are platform-dependent, e.g., path separators differ on Windows (\) and Linux/Mac (/).
8. Checking existence (exists()) before performing operations like delete or create is a good practice to avoid errors.
9. The File class provides metadata and file management only, not file content manipulation.