What are different libraries to generate QR code and example in java

There are several libraries available to generate QR codes in Java. 

Here are a few popular ones:

 1. ZXing: ZXing is a popular open-source library for generating QR codes in Java. 

     It is also known as the "Zebra Crossing" library. 

      Here is an example of how to use ZXing to generate a QR code:

import com.google.zxing.BarcodeFormat;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;

public class QRCodeGenerator {

    public static void main(String[] args) {
        String data = "Hello, World!";
        String fileName = "qrcode.png";
        int size = 250;

        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        BitMatrix bitMatrix;
        try {
            bitMatrix = qrCodeWriter.encode(data, BarcodeFormat.QR_CODE, size, size);
            Path path = FileSystems.getDefault().getPath(fileName);
            MatrixToImageWriter.writeToPath(bitMatrix, "PNG", path);
        } catch (WriterException | IOException e) {
            e.printStackTrace();
        }
    }
}

2. QArt Codes: QArt Codes is a library that allows you to generate artistic QR codes with custom

     designs. Here is an example of how to use QArt Codes to generate a QR code:

import com.github.qartc.qartc.QArt;
import com.github.qartc.qartc.QArtConfig;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class QRCodeGenerator {

    public static void main(String[] args) {
        String data = "Hello, World!";
        String fileName = "qrcode.png";

        QArtConfig config = QArt.newBuilder()
                .data(data)
                .charset("UTF-8")
                .margin(4)
                .build();

        BufferedImage image = QArt.create(config);
        File output = new File(fileName);

        try {
            ImageIO.write(image, "png", output);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

3. QRGen: QRGen is another library for generating QR codes in Java. 

     Here is an example of how to use QRGen to generate a QR code:

import net.glxn.qrgen.core.image.ImageType;
import net.glxn.qrgen.javase.QRCode;

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

public class QRCodeGenerator {

    public static void main(String[] args) {
        String data = "Hello, World!";
        String fileName = "qrcode.png";
        int size = 250;

        QRCode qrCode = QRCode.from(data).withSize(size, size).to(ImageType.PNG);
        File file = new File(fileName);

        try {
            Files.write(file.toPath(), qrCode.stream().toByteArray());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}