How do I set the value of file attributes?

By Wayan in Core API, IO 0 Comment

This code snippet show you an example on how to set the value of file attributes. Here we will set the DosFileAttributes. To set the value of file attributes we use the Files.setAttributes() method. To set DosFileAttributes we can use the following attributes: "dos:archive", "dos:hidden", "dos:readonly" and "dos:system".

For details let’s see the code snippet below:

package org.kodejava.io;

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.DosFileAttributes;

public class UpdateDosFileAttributesExample {
    public static void main(String[] args) throws Exception {
        String path = "D:/resources/data.txt";
        Path file = Paths.get(path);

        // Get current Dos file attributes and print it.
        DosFileAttributes attr = Files.readAttributes(file, DosFileAttributes.class);
        printAttributes(attr);

        // Set a new file attributes.
        Files.setAttribute(file, "dos:archive", false);
        Files.setAttribute(file, "dos:hidden", false);
        Files.setAttribute(file, "dos:readonly", false);
        Files.setAttribute(file, "dos:system", false);

        // Read the newly set file attributes and print it.
        attr = Files.readAttributes(file, DosFileAttributes.class);
        printAttributes(attr);
    }

    /**
     * Print the DosFileAttributes information.
     *
     * @param attr DosFileAttributes.
     */
    private static void printAttributes(DosFileAttributes attr) {
        System.out.println("isArchive()  = " + attr.isArchive());
        System.out.println("isHidden()   = " + attr.isHidden());
        System.out.println("isReadOnly() = " + attr.isReadOnly());
        System.out.println("isSystem()   = " + attr.isSystem());
        System.out.println("----------------------------------------");
    }
}

The output of the code snippet:

isArchive()  = true
isHidden()   = true
isReadOnly() = true
isSystem()   = true
----------------------------------------
isArchive()  = false
isHidden()   = false
isReadOnly() = false
isSystem()   = false
----------------------------------------

How do I write a text file in JDK 7?

By Wayan in Core API, IO 0 Comment

In JDK 7 we can write all lines from a List of String into a file using the Files.write() method. We need to provide the Path of the file we want to write to, the List of strings and the charsets. Each line is a char sequence and is written to the file in sequence with each line terminated by the platform’s line separator.

Let’s see the code snippet below:

package org.kodejava.io;

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

public class WriteTextFile {
    public static void main(String[] args) {
        Path file = Paths.get("D:/resources/data.txt");

        List<String> lines = new ArrayList<>();
        lines.add("Lorem Ipsum is simply dummy text of the printing ");
        lines.add("and typesetting industry. Lorem Ipsum has been the ");
        lines.add("industry's standard dummy text ever since the 1500s, ");
        lines.add("when an unknown printer took a galley of type and ");
        lines.add("scrambled it to make a type specimen book.");

        try {
            // Write lines of text to a file.
            Files.write(file, lines, StandardCharsets.UTF_8);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

This code snippet will create a file called data.txt under the resources folder. Please make sure that this folder is existed before you tried to run the code.

How do I read all lines from a file?

By Wayan in Core API, IO 0 Comment

The java.nio.file.Files.readAllLines() method read all lines from a file. This method ensures that the file is closed when all bytes have been read or an I/O error, or other runtime exception, is thrown. Bytes from the file are decoded into characters using the specified charset.

Note that this method is intended for simple cases where it is convenient to read all lines in a single operation. It is not intended for reading in large files. This method is available since Java 7.

package org.kodejava.io;

import java.net.URI;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.List;
import java.util.Objects;

public class ReadFileAsListDemo {
    public static void main(String[] args) {
        ReadFileAsListDemo demo = new ReadFileAsListDemo();
        demo.readFileAsList();
    }

    private void readFileAsList() {
        String fileName = "/data.txt";

        try {
            URI uri = Objects.requireNonNull(this.getClass().getResource(fileName)).toURI();
            List<String> lines = Files.readAllLines(Paths.get(uri),
                    Charset.defaultCharset());

            for (String line : lines) {
                System.out.println(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

How do I get the extension of a file?

By Wayan in Core API, IO 0 Comment

Below is an example that can be used to get the extension of a file. The code below assume that the extension is the last part of the file name after the last dot symbol. For instance if you have a file named data.txt the extension will be txt, but if you have a file named data.tar.gz the extension will be gz.

package org.kodejava.io;

import java.io.File;

public class FileExtension {
    private static final String EXT_SEPARATOR = ".";

    public static void main(String[] args) {
        File file = new File("data.txt");
        String ext = FileExtension.getFileExtension(file);
        System.out.println("Ext = " + ext);

        file = new File("F:/Temp/Data/data.tar.gz");
        ext = FileExtension.getFileExtension(file);
        System.out.println("Ext = " + ext);

        file = new File("F:/Temp/Data/HelloWorld.java");
        ext = FileExtension.getFileExtension(file);
        System.out.println("Ext = " + ext);
    }

    /**
     * Get the extension of the specified file.
     *
     * @param file a file.
     * @return the extension of the file.
     */
    private static String getFileExtension(File file) {
        if (file == null) {
            return null;
        }

        String name = file.getName();
        int extIndex = name.lastIndexOf(FileExtension.EXT_SEPARATOR);

        if (extIndex == -1) {
            return "";
        } else {
            return name.substring(extIndex + 1);
        }
    }
}

How do I move directory to another directory with its entire contents?

By Wayan in Apache Commons, Commons IO 3 Comments

Below is an example to move one directory with all its child directory and files to another directory. We can use the FileUtils.moveDirectory() method to simplify the process.

package org.kodejava.commons.io;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;

public class DirectoryMove {
    public static void main(String[] args) {
        String source = "F:/Temp/source";
        File srcDir = new File(source);

        String destination = "F:/Temp/target";
        File destDir = new File(destination);

        try {
            // Move the source directory to the destination directory.
            // The destination directory must not exist prior to the
            // move process.
            FileUtils.moveDirectory(srcDir, destDir);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.16.1</version>
</dependency>

Maven Central