Why Can\'t IntelliJ IDEA Find My Java Class at Runtime?

Java Class Not Found Exception When Running in IntelliJ IDEA

When attempting to compile your database-oriented program in IntelliJ IDEA, you encounter the error "java.lang.ClassNotFoundException." This issue arises not during compilation but when executing the application. It indicates that Java cannot locate the Table.class file within the project output directory's db subdirectory (classpath).

Several factors can contribute to this error:

• Incorrect Main Class Configuration: Ensure the correct main class is selected in the run/debug configuration.
• Excluded Table.java Class: Check if Table.java is mistakenly excluded from compilation or due to compilation errors.
• Skipped Build Step: Verify that the "Build" step is included in the run/debug configuration's Before Launch steps.
• Missing Source Root Definition: Confirm that the project has a "Source root" defined for the directory containing the db subdirectory.
• Incorrect Package Statement or Location: Ensure that Table.java has the correct package statement and is located in the proper package.
• Invalid Classpath: Check for colons or semicolons in the project path, as they can invalidate the classpath.
• Digitally Signed Dependent Jars: Jars with partial dependencies may fail to execute.
• Incorrect Java Version: Select the correct Java version for compilation in the project structure.
• Missing Module File or Invalid Name: Fix or recreate the module file if it is corrupted or named untitled104.iml.
• Unicode UTF-8 Setting: Disable the "Beta: Use Unicode UTF-8 for worldwide language support" Region Setting to resolve potential issues.
• Module Dependency Format: Configure the module to use IntelliJ IDEA format dependencies if dependency information is stored in Eclipse format.

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