java - 如何正确地将数组添加到集合中？

Question

我正在尝试将 Integer 数组添加到 Set 中，如下所示，

int[] arr = { 2, 6, 4 , 2, 3, 3, 1, 7 }; 
Set<Integer> set = new HashSet<Integer>(Arrays.asList(arr));

我收到如下错误提示，

myTest.java:192: error: no suitable constructor found for HashSet(List<int[]>)
    Set<Integer> set = new HashSet<Integer>(Arrays.asList(arr));
                       ^
constructor HashSet.HashSet(Collection<? extends Integer>) is not applicable
  (argument mismatch; inferred type does not conform to upper bound(s)
      inferred: int[]
      upper bound(s): Integer,Object)
constructor HashSet.HashSet(int) is not applicable
  (argument mismatch; no instance(s) of type variable(s) T exist so that List<T> conforms to int)
 where T is a type-variable:
T extends Object declared in method <T>asList(T...)
Note: Some messages have been simplified; recompile with -Xdiags:verbose to        get full output
   1 error

其次，我也尝试如下，但仍然出现错误，

int[] arr = { 2, 6, 4 , 2, 3, 3, 1, 7 }; 
Set<Integer> set = new HashSet<Integer>( );
Collections.addAll(set, arr);

如何在 Java 中正确地将 Integer 数组添加到 Set 中？谢谢。

Answer 1

需要使用wrapper类型才能使用Arrays.asList(T...)

Integer[] arr = { 2, 6, 4, 2, 3, 3, 1, 7 };
Set<Integer> set = new HashSet<>(Arrays.asList(arr));

或像手动添加元素

int[] arr = { 2, 6, 4, 2, 3, 3, 1, 7 };
Set<Integer> set = new HashSet<>();
for (int v : arr) {
    set.add(v);
}

最后，如果您需要保留插入顺序，您可以使用 LinkedHashSet .