可变args重载 [英] Overloading with variable args

问题描述

class OverloadingVarargs2 {
    static void f(float i, Character... args) {
        System.out.println("first");
        System.out.println(i);
    }
    static void f(Character... args) {
        System.out.println("second");
    }
    static void test() {
        f(1, 'a');
        f('b', 'c'); // the method f is ambiguous
    }
}

该代码无法编译，编译器说f含糊不清.但是我认为第二种方法可以匹配f('b', 'c');，这是什么问题?

This code can't be compiled, The compiler says that f is ambiguous. But I think the second method can match f('b', 'c'); what's the problem?

推荐答案

这是因为无法确定该方法调用是应该调用带有可变args的方法还是应该调用带有float和可变args的方法.

That is because there is no way to determine if that method call should either call the one with variable args or the one with float and variable args.

Java决定用这种方法来调用widening> boxing>变量args，但是在这种情况下，两者都具有变量args.

Java decides with method to call in this way widening > boxing > variable args, however in this case both have variable args.

在这种情况下，基本将char扩展为浮动.

Basically char is being widened to float in this scenario.

java原语的扩展顺序为:

The widening order for java primitives is:

byte -> short -> int -> long -> float -> double
char -> int -> long -> float -> double

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