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Problem Summary

I’m encountering an issue while working with an ANTLR-generated lexer in Java. Specifically, I get the following error message:

The method getChannelNames() of type ExpressionLexer must override or implement a supertype method

Details:

• File: ExpressionLexer.java
• Path: /Problem Set 3/ps3/src/expressivo/parser
• Line: 119

Additionally, when I try to run the lexer using grun, I receive the following error:

``
Exception in thread "main" java.lang.NoClassDefFoundError: expressivo/parser/ExpressionLexer (wrong name: ExpressionLexer)
    at java.base/java.lang.ClassLoader.defineClass1(Native Method)
    ...
    at org.antlr.v4.gui.TestRig.process(TestRig.java:129)
``

Environment

• ANTLR Version: 4.13
• JDK Version: 17.0.12

1. Verified the package declaration in ExpressionLexer.java matches the directory structure.
2. Checked that the ExpressionLexer.class file is located in the correct directory.
3. Compiled the lexer and parser files using javac
4. Ran the grun command from the correct directory, including the necessary classpath.

I’m working on a project which deals with parsing of polynomials

Despite these efforts, the problem persists. Any guidance on how to resolve this issue would be greatly appreciated.