SnakeYaml class not found exception - maven-3

Question

When I parse config.yaml using SnakeYaml 1.14 I get a "Class not found exception". The following is the code used for parsing. I have used maven to build the project.
public class AppConfigurationReader
{
private static final String CONFIG_FILE = "config.yaml";
private static String fileContents = null;
private static final Logger logger = LoggerFactory.getLogger(AppConfigurationReader.class);
public static synchronized AppConfiguration getConfiguration() {
return getConfiguration(false);
}
public static synchronized AppConfiguration getConfiguration(Boolean forceReload) {
try {
Yaml yaml = new Yaml();
if(null == fileContents || forceReload) {
fileContents = read(CONFIG_FILE);
}
yaml.loadAs(fileContents, AppConfiguration.class);
return yaml.loadAs(fileContents, AppConfiguration.class);
}
catch (Exception ex) {
ex.printStackTrace();
logger.error("Error loading fileContents {}", ex.getStackTrace()[0]);
return null;
}
}
private static String read(String filename) {
try {
return new Scanner(new File(filename)).useDelimiter("\\A").next();
} catch (Exception ex) {
logger.error("Error scanning configuration file {}", filename);
return null;
}
}
}

Answer 1

I too had this, it was due to an incorrect set of dependencies.
I had used
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot</artifactId>
</dependency>
when I should have used
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
The difference being that the latter includes org.yaml:snakeyaml:jar:1.27:compile

Answer 2

May be I am bit late to respond, but it will help others in future.
This issue comes when your class is not able to load the class, sometimes even if it is present in your classpath also.
I encountered this Issue and can be handled in this way.
package my.test.project;
import java.io.InputStream;
import org.yaml.snakeyaml.Yaml;
import org.yaml.snakeyaml.constructor.CustomClassLoaderConstructor;
public class MyTestClass {
public static void main(String[] args) {
InputStream input = MyTestClass.class.getClassLoader().getResourceAsStream("test.yml");
Yaml y = new Yaml(new CustomClassLoaderConstructor(MyTestClass.class.getClassLoader()));
TestConfig test =y.loadAs(input, TestConfig.class);
System.out.println(test);
}
}
You need to initialize Yaml object with CustomClassLoaderConstructor it will help load the bean class before it was actually used internally.

Answer 3

I have found a similar error but dumping a file.
You could write the complete name of the class in yaml.load instruction.
For example, if AppConfiguration.class was in org.example.package1, you would write something like:
yaml.loadAs(fileContents, org.example.package1.AppConfiguration.class);

Answer 4

Seems like snakeyaml libraries are not included in your jar file, you have to use the maven assembly plugin eather than just package, so that all the dependency jars gets included