是什么导致了这个错误；java:6:错误：找不到符号导入org.antlr.v4.runtime.CharStreams&引用；？

我不断得到错误：

import java.io.*;
import org.antlr.v4.runtime.tree.*;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.CharStreams;
import org.antlr.v4.runtime.CommonTokenStream;


public class Eval {

    public static void main(String[] args) {
        if (args.length != 1) {
            System.err.print("Usage: file");
        } else {
            String file = args[0];
            GrammarParser parser = getParser(file);
            ParseTree AbstractSynTree = parser.prog();
            AntlrToProgram programVisitor = new AntlrToProgram();
            Program prg = programVisitor.visit(AbstractSynTree);

        }

    }

    public static GrammarParser getParser(String file) {
        GrammarParser parser = null;
        try {
            CharStream input = CharStreams.fromFileName(file);
            GrammarLexer lexer = new GrammarLexer(input);
            CommonTokenStream tokens = new CommonTokenStream(lexer);
            parser = new GrammarParser(tokens);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return parser;
    }
}

---

编译Eval.java时。我不确定发生了什么，因为所有其他Antlr类都在导入，所以我假设类路径已正确导入。非常感谢您的帮助，谢谢

查看的源代码，您可以看到它是在ANTLR 4.7中引入的。您很可能正在使用下面的ANTLR版本。

非常感谢您的回答！！！！结果发现我的类路径中有错误版本的antlr。不客气@racoononroids

Eval.java:6: error: cannot find symbol
import org.antlr.v4.runtime.CharStreams;
                           ^
  symbol:   class CharStreams
  location: package org.antlr.v4.runtime
Eval.java:29: error: cannot find symbol
            CharStream input = CharStreams.fromFileName(file);
                               ^
  symbol:   variable CharStreams
  location: class Eval
2 errors