使用Java中的Scala：将函数作为参数传递
Consider the following Scala code:
请考虑以下Scala代码：
package scala_java
object MyScala {
def setFunc(func: Int => String) {
func(10)
}
}
Now in Java, I would have liked to use MyScala as:
现在在Java中，我本来希望使用MyScala：
package scala_java;
public class MyJava {
public static void main(String [] args) {
MyScala.setFunc(myFunc); // This line gives an error
}
public static String myFunc(int someInt) {
return String.valueOf(someInt);
}
}
However, the above does not work (as expected since Java does not allow functional programming). What is the easiest workaround to pass a function in Java? I would like a generic solution that works with functions having arbitrary number of parameters.
但是，上述方法不起作用（正如预期的那样，因为Java不允许进行函数式编程）。在Java中传递函数最简单的解决方法是什么？我想要一个适用于具有任意数量参数的函数的通用解决方案。
EDIT: Does Java 8 have any better syntax than the classic solutions discussed below?
编辑：Java 8是否有比下面讨论的经典解决方案更好的语法？
4 个解决方案
#1
26
You have to manually instantiate a Function1 in Java. Something like:
您必须在Java中手动实例化Function1。就像是：
final Function1<Integer, String> f = new Function1<Integer, String>() {
public int $tag() {
return Function1$class.$tag(this);
}
public <A> Function1<A, String> compose(Function1<A, Integer> f) {
return Function1$class.compose(this, f);
}
public String apply(Integer someInt) {
return myFunc(someInt);
}
};
MyScala.setFunc(f);
This is taken from Daniel Spiewak’s “Interop Between Java and Scala” article.
这取自Daniel Spiewak的“Interop Between Java和Scala”一文。