Java:删除 "Comparable is a raw type"警告

Question

假设我有一个名为 foo 的方法，将 2 个对象作为参数。这两个对象属于同一类型，并且都实现了可比较的接口(interface)。

void foo(Object first, Object second){

    if (!first.getClass().isInstance(second))   //first and second of the same type
        return;

    Comparable firstComparable = (Comparable)first;  //WARNING
    Comparable secondComparable = (Comparable)second;  //WARNING

    int diff = firstComparable.compareTo(secondComparable);  //WARNING
}

前两个警告是:

Comparable is a raw type. References to generic type Comparable should be parameterized

最后的警告:

Type safety: The method compareTo(Object) belongs to the raw type Comparable. References to generic type Comparable should be parameterized

我如何重构我的代码以移除这些警告？

编辑:我可以在不更改 foo 方法签名的情况下这样做吗？

Answer 1

你必须告诉编译器它们是同一类型并且具有可比性。如果您无法更改签名，则可以添加一种方法以实现向后兼容性。

@SuppressWarnings("unchecked")
static void foo(Object first, Object second) {
    foo((Comparable) first, (Comparable) second);
}

static <T extends Comparable<T>> void foo(T first, T second){
    int diff = first.compareTo(second); // no warning.
}