How to specify a target package for ANTLR?

If I call:

java org.antlr.Tool -o outdir sources/com/example/Java5.g

...with antlr-3.1.3 the parser and lexer code will be generated in the directory outdir/sources/com/example. But the generated classes don't have any package statement. I need them to life in the package com.example.

Is there a way to specify the target package?

ANTLR provides a header tool which allows you to include package and imports. You include this in your *.g grammar file:

@header {
    package org.xmlcml.cml.converters.antlr;
    import java.util.HashMap;
}

And you may need it in the Lexer as well:

@lexer::header {package org.xmlcml.cml.converters.antlr;}

and in case you need to add some members and code:

@members {
    HashMap<String, Object> objectMap = new HashMap<String, Object>();
    //...

    private void addArrayValue(String content) {
    //... code required by snippets in the grammar

    }
}

An old question with a perfectly good answer, but since the comment on the question asked for a command line option (and that was what I was actually searching for when I got here), I thought I'd just chime in and say the following...

You can specifiy the package on the command line if you are using ANTLR 4. I checked and it seems to not be there in version 3 so the other answer is the way to go for ANTLR 3.

Here is an example:

java -cp antlr-4.4-complete.jar org.antlr.v4.Tool -package my.package MyGram.g4

See the -package option at ANTLR Tool Command Line Options for more information.