Java Files

In Java, working with files typically involves reading from or writing to files. Java provides classes in the java.io and java.nio.file packages to make file operations easy and efficient. Here's an overview with examples of how to perform common file operations:

Reading a File

Using BufferedReader

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class ReadFileExample {
    public static void main(String[] args) {
        String filePath = "example.txt";

        try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = br.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    

Using Files.readAllLines

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

public class ReadFileWithFiles {
    public static void main(String[] args) {
        String filePath = "example.txt";
        
        try {
            List<String> lines = Files.readAllLines(Paths.get(filePath));
            for (String line : lines) {
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    

Writing to a File

Using BufferedWriter

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;

public class WriteFileExample {
    public static void main(String[] args) {
        String filePath = "output.txt";
        String content = "Hello, Java File Writing!";
        
        try (BufferedWriter bw = new BufferedWriter(new FileWriter(filePath))) {
            bw.write(content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    

Using Files.write

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

public class WriteFileWithFiles {
    public static void main(String[] args) {
        String filePath = "output.txt";
        List<String> content = Arrays.asList("Line 1", "Line 2", "Line 3");

        try {
            Files.write(Paths.get(filePath), content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    

Appending to a File

Using FileWriter with append mode

import java.io.FileWriter;
import java.io.IOException;

public class AppendFileExample {
    public static void main(String[] args) {
        String filePath = "output.txt";
        String contentToAppend = "This line will be appended!";

        try (FileWriter fw = new FileWriter(filePath, true)) {
            fw.write(contentToAppend + "\n");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    

Deleting a File

Using Files.delete

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

public class DeleteFileExample {
    public static void main(String[] args) {
        String filePath = "output.txt";
        Path path = Paths.get(filePath);

        try {
            Files.delete(path);
            System.out.println("File deleted successfully");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    

Checking if a File Exists

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

public class CheckFileExistence {
    public static void main(String[] args) {
        String filePath = "example.txt";

        if (Files.exists(Paths.get(filePath))) {
            System.out.println("File exists!");
        } else {
            System.out.println("File does not exist.");
        }
    }
}
    

Copying and Moving Files

Copying a File

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

public class CopyFileExample {
    public static void main(String[] args) {
        String sourcePath = "source.txt";
        String destinationPath = "destination.txt";

        try {
            Files.copy(Paths.get(sourcePath), Paths.get(destinationPath));
            System.out.println("File copied successfully!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
    

Moving a File

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

public class MoveFileExample {
    public static void main(String[] args) {
        String sourcePath = "source.txt";
        String destinationPath = "destination.txt";

        try {
            Files.move(Paths.get(sourcePath), Paths.get(destinationPath));
            System.out.println("File moved successfully!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}