Java 不兼容的类型：推理变量 T 有不兼容的边界
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incompatible types: inference variable T has incompatible bounds
提问by PDStat
I have the following piece of code
我有以下代码
public int solution(int X, int[] A) {
List<Integer> list = Arrays.asList(A);
For some reason it's throwing the following compilation error
出于某种原因，它抛出以下编译错误
Solution.java:11: error: incompatible types: inference variable T has incompatible bounds List list = Arrays.asList(A); ^ equality constraints: Integer lower bounds: int[] where T is a type-variable: T extends Object declared in method asList(T...)
Solution.java:11: error: incompatible types: inference variable T has incompatible bounds List list = Arrays.asList(A); ^ 等式约束：整数下界：int[] 其中 T 是类型变量：T extends Object 在方法 asList(T...) 中声明
I assume this a Java 8 feature, but I'm not sure how to resolve the error
我认为这是 Java 8 功能，但我不确定如何解决该错误
采纳答案by tobias_k
Arrays.asListis expecting a variable number of Object. intis not an Object, but int[]is, thus Arrays.asList(A)will create a List<int[]>with just one element.
Arrays.asList期待可变数量的Object。int不是 an Object，而是int[]is，因此Arrays.asList(A)将创建一个List<int[]>只有一个元素的 a 。
You can use IntStream.of(A).boxed().collect(Collectors.toList());
您可以使用 IntStream.of(A).boxed().collect(Collectors.toList());
回答by Sagar Koshti
There is no shortcut for converting from int[] to List as Arrays.asList does not deal with boxing and will just create a List which is not what you want. You have to make a utility method.
从 int[] 转换为 List 没有捷径，因为 Arrays.asList 不处理装箱，只会创建一个不是您想要的 List。你必须制定一个实用方法。
int[] ints = {1, 2, 3};
List<Integer> intList = new ArrayList<Integer>();
for (int index = 0; index < ints.length; index++)
{
intList.add(ints[index]);
}
回答by Peter Lawrey
In Java 8 you can do
在 Java 8 中你可以做
List<Integer> list = IntStream.of(a).boxed().collect(Collectors.toList());
