Java NIO Create, Write, Read and Delete Files

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In this tutorial, we will learn how to create, write, read and remove files using Java NIO package APIs.

Java Create File Example 

We use Files.createFile() method to create a file in Java.

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.HashSet;
import java.util.Set;

public class JavaCreateFile {

    public static void main(String[] args) throws IOException {

        Set<PosixFilePermission> perms = new HashSet<>();

        perms.add(PosixFilePermission.OWNER_READ);
        perms.add(PosixFilePermission.OWNER_WRITE);
        perms.add(PosixFilePermission.GROUP_READ);
        perms.add(PosixFilePermission.GROUP_WRITE);
        perms.add(PosixFilePermission.OTHERS_READ);

        FileAttribute<Set<PosixFilePermission>> attrs = PosixFilePermissions.asFileAttribute(perms);

        Path myPath = Paths.get("src/resources/sample.txt");

        if (Files.exists(myPath)) {
            
            System.out.println("File already exists");
        } else {
            
            Files.createFile(myPath, attrs);
            System.out.println("File created");
        }
    }
}

Create a new file named "sample.txt" if the file does not exist:

        if (Files.exists(myPath)) {
            
            System.out.println("File already exists");
        } else {
            
            Files.createFile(myPath, attrs);
            System.out.println("File created");
        }

Java Write File Example

We use Files.write() method to write a text or string to the given file.

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.List;

public class JavaWriteFile {

    public static void main(String[] args) throws IOException {
        
        Path myPath = Paths.get("src/resources/sample.txt");
        
        List<String> lines = new ArrayList<>();
        lines.add("mango");
        lines.add("apple");
        lines.add("banana");
        lines.add("watermelon");
        lines.add("orange");
        
        Files.write(myPath, lines, StandardCharsets.UTF_8, 
                StandardOpenOption.CREATE);
        
        System.out.println("Data written to a file");
    }
}

Java Read File Example

We use Files.readAllLines() method to read all lines from a given file.

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

public class JavaReadFile {

    public static void main(String[] args) throws IOException {
        
        Path myPath = Paths.get("src/resources/sample.txt");
        
        List<String> lines = Files.readAllLines(myPath, StandardCharsets.UTF_8);
        
        lines.forEach(line -> System.out.println(line));
    }
}

Java Delete File Example

We use Files.deleteIfExists() method to delete a file if it exists.

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

public class JavaDeleteFile {

    public static void main(String[] args) throws IOException {
        
        Path myPath = Paths.get("src/resources/sample.txt");
        
        boolean fileDeleted = Files.deleteIfExists(myPath);
        
        if (fileDeleted) {
            
            System.out.println("File deleted");
        } else {
            
            System.out.println("File does not exist");
        }
    }
}

Output:

File deleted

References

https://docs.oracle.com/en/java/javase/18/docs/api/java.base/java/nio/file/Files.html

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