[Solved] NoSuchFieldError: Class com.sun.tools.javac.tree.JCTree $JCImport
When rebuilding a Java or Spring application, after upgrading Java 21, you may face the issue “NoSuchFieldError: Class JCTree$JCImport does not have member field”.
[Solved] JAXB Error: No default constructor found on class
Learn to solve the error “No default constructor found” when unmarshaling an XML to Java object using JAXB @XmlTransient and @XmlJavaTypeAdapter annotations.
[Solved] This version of ChromeDriver only supports Chrome version
Learn to fix the selenium WebDriver error “This version of ChromeDriver only supports Chrome version” during UI testing.
[Solved] Maven – Fatal error compiling: invalid target release
Learn to fix Maven invalid target release error which indicates that Java versions used in Maven and in the application are not compatible.
Gson TypeAdapters for Java 8 LocalDate/Time Classes
Learn to fix the InaccessibleObjectException or “Failed making field ‘java.time.LocalDate#year’ accessible” type errors when serializing or deserializing the new Java 8 Date time classes.
Troubleshooting OutOfMemoryError in Java
The OutOfMemoryError is a common issue in Java applications, occurring when the JVM cannot allocate enough memory to fulfill a request.
[Solved] Java class file has wrong version 61.0
Learn to solve the Java compiler exception “Java class file has wrong version” while migrating an application to Spring 6 or Spring boot 3.
Handle Exceptions Thrown in Java Streams
Learn to handle the checked exceptions thrown from the methods used in Stream operations in Java 8 using safe method extraction and Optional.
Java UnsupportedOperationException
Java UnsupportedOperationException is an unchecked exception and occurs when a requested operation is not supported in a class.
[Solved] “Stream has already been operated upon or closed” Exception
Learned the root cause and solution of the Java Stream exception “IllegalStateException: stream has already been operated upon or closed”.
Java – How to Handle InterruptedException
Learn InterruptedException and when it is thrown with examples. We will also see how we can handle this exception in our code.
Jackson Error: Java 8 date/time type not supported by default
Learn to fix the error ‘Java 8 date/time type not supported by default’ while serializing and deserializing Java 8 Date time classes using Jackson.
Resolving IllegalMonitorStateException In Java
Learn IllegalMonitorStateException, when it is thrown with examples. We will also see how we can prevent our code from raising this exception
Java ArrayStoreException and How to resolve it?
Learn why we get the ArrayStoreException while working with arrays in Java and how to identify the root cause and fix this error. 1. Root Cause of ArrayStoreException Java arrays are covariant and support the subtyping rules of Java, an array of type T[] may contain elements of type T …
[Solved] Error: Could not find or load main class
We may get this error (Could not find or load main class) while running the Java class (e.g. Hello world application) from the system console. We get this error because we are incorrectly trying to run the main() inside the class using java command. 1. Reason for error – could …
Java 14 – Helpful NullPointerException (NPE)
Java 14 (JEP 358) improves the usability of NullPointerException generated by the JVM by describing precisely which variable was null. Lets understand this in detail. 1. Better NullPointerException First, we need to pass -XX:+ShowCodeDetailsInExceptionMessages JVM flag to enable this feature while running the application. Make sure, you are passing it. …
REST API Error Handling in Spring Boot
Learn to handle exceptions locally and globally in Spring Boot REST APIs using @ControllerAdvice, @ExceptionHandler, and other latest approaches.
Java throw and throws Keywords
In Java exception handling, throw keyword is used to explicitly throw an exception from a method or constructor. And throws keyword is used to declare the list of exceptions that may be thrown by that method or constructor. 1. Throw Let us learn basic things about throw keyword before going …
Java try catch finally
Java try catch finally blocks helps in writing the application code which may throw exceptions in runtime and gives us chance to recover from the exception.
[Solved] java.security.InvalidKeyException: Parameters missing
You may get InvalidKeyException: Parameters missing error while performing AES encryption or decryption for password or any senstive information.
[Solved] JAXB UnmarshalException: unexpected element
Java example of unmarshaling a bean without jaxb annotations. Learn to unmarshal java objects with missing @XmlRootElement.
[SOLVED] TLS 1.2 – SSLHandshakeException: Remote host closed connection during handshake
SSLHandshakeException appear in logs when there is some error occur while validating the certificate installed in client machine with certificate on server machine. In this post, we will learn about fixing this if you are using Apache HttpClient library to create HttpClient to connect to SSL/TLS secured URLs.
Enable Debug Logging for SSL Issues in Java
To triage SSL issues, enable SSL debug logging by passing javax.net.debug=ssl runtime argument to your server/program.
[Solved] java.lang.ClassNotFoundException: org.apache.commons.fileupload.FileItemFactory
I encountered this exception while building spring MVC file upload example. The error stacktrace looks like this: Solution You have incorrect version of apache commons-fileupload. To solve this error, you correct version 1.2.1. This will solve your error. Happy Learning !!
Why Java Iterator throws ConcurrentModificationException?
When Java Iterator detects the modifications, it cannot guarantee iteration consistency and throws the ConcurrentModificationException.
Jersey exception handling – Jersey ExceptionMapper Example
In Jersey ExceptionMapper example, we will learn to handle custom exceptions using ExceptionMapper interface while developing Jersey RESTful web services. For demo purpose, I am modifying the sourcecode written for jersey download file example. Table Of Contents 1. Jersey custom exception with ExceptionMapper 2. How to throw exception from REST …
[Solved] java.lang.NoClassDefFoundError: Could not initialize class org.hibernate.validator.engine.ConfigurationImpl
If you are working on spring MVC web application and you are trying to use JSR-303 validation annotations then you might face this exception. Exception stack trace looks like this. Solution This problem is due to incorrect version of “hibernate-validator” dependency. You need to try other versions of this dependency …
[Solved] The superclass “javax.servlet.http.HttpServlet” was not found on the Java Build Path in Eclipse
1. Problem If you are facing this error after importing an existing maven project into your eclipse IDE, then it means that http-servlet is not available in the project’s classpath and you must include it. The error looks like this. 2. Solution To include http-servlet into your classpath, you have …
Restarting threads using UncaughtExceptionHandler
1. UncaughtExceptionHandler Java applications have two kind of exceptions – checked exceptions and unchecked exceptions. Checked exceptions must be specified in the throws clause of a method or caught inside them. Unchecked exceptions don’t have to be specified or caught. When a checked exception is thrown inside the run() method …
[Solved] java.lang.IllegalStateException: No match found while using Regex Named Groups
You will get this exception message when you are trying to use named groups in java regex validation or matching. Root Cause of No match found Error in Regex Named Group Matching Error log will show the message like below: Solution You are probably not using “matcher.matches()” before fetching the …
Guide to Java 8 Optional
All of us must have encountered NullPointerException in our applications. It happens when you try to use an object that has not been initialized, initialized with null or does not point to any instance. In simple words, NULL simply means ‘absence of a value’. In this Java tutorial, we will …
[Solved] java.lang.ClassNotFoundException: org.springframework.web.context.ContextLoaderListener
Learn to fix the ContextLoaderListener class not found error that is present used in a web application and is part of the spring-web module.
[Solved] java.lang.IllegalArgumentException: taglib definition not consistent with specification version
If you are working on a web application and you define the taglibs in your web.xml file then you may encounter this exception. The exception trace in server console looks like this when you start up the server. Solution You just need to confirm the allowed tags by web.xml confirming …
Java Checked vs Unchecked Exceptions
Learn the difference between checked vs unchecked exceptions in Java, with simple explanations and examples. Learn Java exception handling best practices.
Handle Exceptions thrown from Initializer Blocks in Java
Learn to handle the exceptions thrown from the instance or static initializer blocks in Java by declaring them in constructors.
[SOLVED] java.lang.ClassNotFoundException: org.glassfish.jersey.client.JerseyClientBuilder
If you are using RESTEasy 3.x.y which has been support for JAX-RS 2.0, and you are trying to write RESTEasy client then you can face this exception. Full stack trace might look like this: Root cause Probably you are following trying to wrire the client code as follows: JAX-RS relies …
SOLVED: java.lang.ClassNotFoundException: com.sun.jersey.spi.container.servlet.ServletContainer
If you have started working on Jersey then you might face this issue while configuring it. This is the result of insufficient project dependencies on runtime. This issue is likely to be faced in the tomcat server. The Error The error log will look like this. The Solution To solve …
[Solved] java.lang.IncompatibleClassChangeError: Implementing class
Reason When you are working with java libraries that internally depend on cglib, then it’s very normal to encounter the below error: This error is due to an incompatible version of cglib with additional jar files in your project, such as asm. Solution The solution is very easy. Just place …
Java NullPointerException
Java NullPointerException (NPE) is an unchecked exception and extends RuntimeException. NullPointerException doesn’t force us to use a try-catch block to handle it. NullPointerException has been very much a nightmare for most Java developers. It usually pop up when we least expect them. I have also spent a lot of time …
Java Exception Handling: 20 Best Practices for Error-Free Code
In this Java exception handling tutorial, learn a few important best practices to write robust application code which is error-free as well.
Java Suppressed Exceptions with Examples
Suppressed exceptions, as name suggest, are exceptions thrown in the code but were ignored somehow. If you remember try-catch-finally block execution sequence and how they return any value or exceptions, you will recall that exceptions thrown in finally block are suppressed if an exception is thrown in try block also. …
Java Synchronous and Asynchronous Exceptions
In this Java tutorial, learn about asynchronous and synchronous exceptions in Java. Also, learn how they are different with checked and unchecked exceptions. 1. Asynchronous and synchronous exceptions Normally Java differentiates the exceptions into two categories on basis of “timing” when they are discovered. These categories are checked and unchecked …
Effective Approach for Creating Custom Exceptions in Java
In contrast to traditional custom exceptions, the new approach uses static inner classes for every new exceptional scenario.