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java.lang.NoClassDefFoundError: java/applet/Applet on modern JDKs (Java 26+) due to legacy Applet references

Aberta
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Avaliação

Dificuldade
3/5
Tempo estimado
Meio dia
Facilidade para iniciantes
35/100
Tipo de issue
Bug
Clareza
Razoavelmente clara
Status de atividade
Ativa
Stack de tecnologia
java
Domínio
testing

Direção de pesquisa

The stack trace points to BasePosRobotIT.setUpBase at line 83, which is in the reporter's own project, not in AssertJ Swing's sources. First, grep the repository for java.applet and JApplet references and run the test suite on JDK 26 to confirm where the missing class is loaded. If the reference only exists in the reporter's code, the fix belongs there, and the issue should be narrowed. Done when the cause is identified and either a library change or a clear out-of-scope conclusion is recorded.

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Descrição

Description

When running UI automation tests built on top of AssertJ Swing under modern JDK environments, specifically JDK 26 or newer, the test suite crashes during initialization with a java.lang.NoClassDefFoundError targeting java/applet/Applet.

The Applet API has been completely removed from the standard JDK classpath in Java 26 under [JEP 504: Remove the Applet API].
Since AssertJ Swing still carries legacy references, internal fixtures, or utilities inherited from the original FEST Swing codebase that depend on java.applet.Applet, the framework fails immediately upon class loading.

Stack Trace
java.lang.NoClassDefFoundError: java/applet/Applet
	at io.github.kriolos.opos.automation.BasePosRobotIT.setUpBase(BasePosRobotIT.java:83)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1612)
Caused by: java.lang.ClassNotFoundException: java.applet.Applet
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:502)
Environment
  • Java Version: JDK 26+ (JEP 504 compliant)
  • OS: Agnostic
  • Library: AssertJ Swing (Core automation engine)
Expected Behavior

AssertJ Swing should be executable on modern standard runtimes (JDK 26+) without requiring or resolving deprecated and now-deleted packages like java.applet.*.

Suggested Fix
  1. Completely remove or refactor any code paths, modules, or internal test runners (such as legacy Applet viewers/fixtures) that reference java.applet.Applet or javax.swing.JApplet.
  2. Fully decouple standard desktop JFrame components from any Applet-based class loading mechanisms to restore compatibility with current and future JDK ecosystems.
Linguagem predominante
Java
Estrelas
121
Forks
52
Nenhum PR com merge em 30d

Preparar o ambiente

Primeiros passos

  1. Leia a issue inteira e depois o guia de contribuição do projeto.
  2. Comente na issue dizendo que vai assumir — evita que duas pessoas façam o mesmo trabalho.
  3. Faça um fork do repositório e trabalhe em uma branch.
  4. Abra um pull request que referencie o número da issue.

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