java - 列表中的通用可比对象出现问题

Question

我想让下面的方法不显示关于使用原始类型的警告，但我想不出告诉它做我想做的事的语法。这是当前的方法:

static long countSplitInversions(List<? extends Comparable> list) {
    long inversions = 0;

    final int leftLimit = list.size() / 2;
    int left = 0;
    int right = leftLimit;

    for (int i = 0; i < list.size(); i++) {
        if (left == leftLimit || right == list.size()) {
            break;
        }
        if (list.get(left).compareTo(list.get(right)) <= 0) {
            left++;
        } else {
            right++;
            inversions += leftLimit - left;
        }
    }

    return inversions;
}

当我更改签名以避免警告时:

static <T> long countSplitInversions(List<? extends Comparable<? super T>> list)

那么 compareTo 所在的行将不会编译错误:

Method compareTo in interface java.lang.Comparable<T> cannot be applied to given tyes
required: capture #1 of ? super T
found: java.lang.Comparable<? super T>

Answer 1

考虑将您的方法签名更改为...

static <T extends Comparable<? super T>> long countSplitInversions(List<T> list) {