找不到符号

Question

我有一个名为"Test.g4“的ANTLR项目，我使用antlrworks2创建的文件没有任何问题: Test.tokens、TestBaseListner.java、TestLexer.java、TestLexer.tokens、TestListener.java和TestParser.java。

现在，我想在我的程序Test.java中使用语法：

import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.tree.*;

public class Test {
    public static void main(String[] args) throws Exception {
        // create a CharStream that reads from standard input
        ANTLRInputStream input = new ANTLRInputStream(System.in);

        // create a lexer that feeds off of input CharStream
        TestLexer lexer = new TestLexer(input);

        // create a buffer of tokens pulled from the lexer
        CommonTokenStream tokens = new CommonTokenStream(lexer);

        // create a parser that feeds off the tokens buffer
        TestParser parser = new TestParser(tokens);

        ParseTree tree = parser.init(); // begin parsing at init rule
        System.out.println(tree.toStringTree(parser)); // print LISP-style tree
    }
}

当我尝试用"javac -classpath /path/java2/antlr-4.4-complete.jar Test.java"编译它时，我会得到以下错误：

Test.java:19: error: cannot find symbol
        TestLexer lexer = new TestLexer(input);
        ^
  symbol:   class TestLexer
  location: class Test
Test.java:19: error: cannot find symbol
        TestLexer lexer = new TestLexer(input);
                                        ^
  symbol:   class TestLexer
  location: class Test
Test.java:25: error: cannot find symbol
        TestParser parser = new TestParser(tokens);
        ^
  symbol:   class TestParser
  location: class Test
Test.java:25: error: cannot find symbol
        TestParser parser = new TestParser(tokens);
                                          ^
  symbol:   class TestParser
  location: class Test
4 errors

谢谢!

Answer 1

TestLexer.java和TestParser.java也应该在同一个命令中使用Test.java编译，否则编译器将不知道在哪里查找它们的二进制文件。尝试按以下方式调用javac：

javac -classpath /path/java2/antlr-4.4-complete.jar *java

或者手动传递所有文件：

javac -classpath /path/java2/antlr-4.4-complete.jar Test.java TestLexer.java TestParser.java

Answer 2

您需要构建和导入由ANTLR生成的lexer和解析器。要做到这一点，你需要：

1. 使用main方法将导入语句添加到文件中
2. 将ANTLR生成的类放入包中，如导入语句中所示
3. 使用主方法构建生成的类和类