我想在Java中将数组转换为Set。有一些明显的方法可以做到这一点(即使用循环),但我想做一些更整洁的事情,比如:

java.util.Arrays.asList(Object[] a);

有什么想法吗?


当前回答

private Map<Integer, Set<Integer>> nobreaks = new HashMap();
nobreaks.put(1, new HashSet(Arrays.asList(new int[]{2, 4, 5})));
System.out.println("expected size is 3: " +nobreaks.get(1).size());

输出为

expected size is 3: 1

将其更改为

nobreaks.put(1, new HashSet(Arrays.asList( 2, 4, 5 )));

输出为

expected size is 3: 3

其他回答

new HashSet<Object>(Arrays.asList(Object[]a));

但我认为这会更有效率:

final Set s = new HashSet<Object>();    
for (Object o : a) { s.add(o); }         

这样地:

Set<T> mySet = new HashSet<>(Arrays.asList(someArray));

在Java 9+中,如果不可修改集合正常:

Set<T> mySet = Set.of(someArray);

在Java 10+中,可以从数组组件类型推断出泛型类型参数:

var mySet = Set.of(someArray);

小心

Set.of抛出IllegalArgumentException-如果有任何重复someArray中的元素。查看更多详细信息:https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Set.html#of(例如…)

使用stanford-stagger-3.0.jar中的CollectionUtils或ArrayUtils

import static edu.stanford.nlp.util.ArrayUtils.asSet;
or 
import static edu.stanford.nlp.util.CollectionUtils.asSet;

  ...
String [] array = {"1", "q"};
Set<String> trackIds = asSet(array);

Varargs也会起作用!

Stream.of(T... values).collect(Collectors.toSet());

快速:您可以做到:

// Fixed-size list
List list = Arrays.asList(array);

// Growable list
list = new LinkedList(Arrays.asList(array));

// Duplicate elements are discarded
Set set = new HashSet(Arrays.asList(array));

并反转

// Create an array containing the elements in a list
Object[] objectArray = list.toArray();
MyClass[] array = (MyClass[])list.toArray(new MyClass[list.size()]);

// Create an array containing the elements in a set
objectArray = set.toArray();
array = (MyClass[])set.toArray(new MyClass[set.size()]);