我可以使用scala类来实现Java的Java接口吗？ [英] Can I use a scala class which implements a java interface from Java?

问题描述

我正在学习Scala并且好奇是否有可能：

I'm learning Scala and was curious if it would be possible to:

1. 创建一个在Scala中实现Java接口的对象


2. 将对象编译成类文件并将其jar起来


3. 使用Java中的对象

我想在scala中实现一个自定义lucene查询解析器，并且能够让其他人从java应用程序访问它。

I want to implement a custom lucene query parser in scala and be able to let others access it from a java application.

推荐答案

我假设对象你实际上是指阶级。无论如何，答案是肯定的，你可以这样做。如果您希望在同一个项目中使用Scala / Java联合编译器，则需要利用它。例如：

I'm assuming that by "object" you actually mean "class". In any case, the answer is yes, you can do this. You will need to take advantage of the Scala/Java joint compiler if you want this all in the same project. For example:

public interface Parser {
    public TokenIterator parse(InputStream is);
}

然后在Scala中：

class ParserImpl extends Parser {
  def parse(is: InputStream) = ...
}

最后，再次使用Java：

Finally, in Java again:

public class Consumer {
    public static void main(String[] args) {
        Parser p = new ParserImpl();       // just like a Java class!
        ...
    }
}

如果所有这些源文件在同一个项目中，然后您将需要使用以下命令调用来编译它们：

If all of these source files are in the same project, then you will want to compile them using the following invocation of commands:

$ scalac *.scala *.java
$ javac -classpath . *.java

第一个命令调用Scala / Java联合编译器，它将编译Scala源代码和只需足够的Java源来满足任何依赖关系。第二个命令使用类路径上最近编译的Scala类调用Java编译器。

The first command invokes the Scala/Java joint compiler, which will compile the Scala sources and just enough of the Java sources to satisfy any dependencies. The second command invokes the Java compiler with the recently-compiled Scala classes on the classpath.

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