Exception java.lang.NoSuchMethodError with qrgen and zxing libraries

问题

Normally, I use maven in my project but because of some migration problems I have to (temporally) download jars.

I want to use the following code:

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

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

public class Main {
    public static void main(String[] args) {
        ByteArrayOutputStream out = QRCode.from("Hello World")
                                        .to(ImageType.PNG).stream();

        try {
            FileOutputStream fout = new FileOutputStream(new File(
                    "C:\\QR_Code.JPG"));

            fout.write(out.toByteArray());

            fout.flush();
            fout.close();

        } catch (FileNotFoundException e) {
            // Do Logging
        } catch (IOException e) {
            // Do Logging
        }
    }
}

I added one jar to my project:

qrgen-1.3.jar

but then, I had got an exception:

Exception in thread "main" java.lang.NoClassDefFoundError: com/google/zxing/Writer

so I added two other jars:

zxing-core-1.7.jar
zxing-j2se-1.7.jar

and now, I have got another error:

Exception in thread "main" java.lang.NoSuchMethodError: com.google.zxing.Writer.encode(Ljava/lang/String;Lcom/google/zxing/BarcodeFormat;IILjava/util/Map;)Lcom/google/zxing/common/BitMatrix;

and here I cannot fix it.

Where could be a problem?

I am sure it goes from first line fo my code:

ByteArrayOutputStream out = QRCode.from("Hello World").to(ImageType.PNG).stream();

回答1:

Well, you are using this library with the wrong version of zxing. Looks like 1.3 uses 2.0, and you are pairing it with 1.7: https://github.com/kenglxn/QRGen/blob/e74f7912e19eb99c84100d5840e2be2e48108747/pom.xml#L40

This is almost always what these kinds of errors mean. Using a tool like Maven avoids this. Also, both versions of these dependencies are old now.

回答2:

NoSuchMethodError is a "linkage" error -- it can't occur at compile if you have all consistent versions of your classes, it only occurs at runtime when code tries to call different versions that don't have the expected method.

Bottom line: your JAR versions are incompatible, most likely between interfaces & implementations.

See: http://docs.oracle.com/javase/7/docs/api/java/lang/NoSuchMethodError.html

回答3:

I used QRGen/ZXING for my JavaEE web application. By trial, these were needed:

.jar:

qrgen-core-2.0
qrgen-javase-2.0
zxing-core-3.1.0
zxing-javase-3.1.0

(At least for this combination, I can confirm these .jar versions work with each other.)

Import:

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

Below are links where the latest .jar files can be downloaded:

QRGen
ZXING

回答4:

try with qrgen-1.0.jar.That would do this work for you.

来源：https://stackoverflow.com/questions/22781101/exception-java-lang-nosuchmethoderror-with-qrgen-and-zxing-libraries

标签

java

jar

qr-code

zxing

nosuchmethoderror