Java中两个集合的对称差
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Symmetric difference of two sets in Java
提问by Abhij
There are two TreeSets in my app:
TreeSet我的应用程序中有两个：
set1 = {501,502,503,504}
set2 = {502,503,504,505}
I want to get the symmetric differenceof these sets so that my output would be the set:
我想得到这些集合的对称差异，以便我的输出是集合：
set = {501,505}
采纳答案by Donal Fellows
You're after the symmetric difference. This is discussed in the Java tutorial.
你在追求对称差异。这在Java 教程中进行了讨论。
Set<Type> symmetricDiff = new HashSet<Type>(set1);
symmetricDiff.addAll(set2);
// symmetricDiff now contains the union
Set<Type> tmp = new HashSet<Type>(set1);
tmp.retainAll(set2);
// tmp now contains the intersection
symmetricDiff.removeAll(tmp);
// union minus intersection equals symmetric-difference
回答by digitebs
use retain all,remove all then addAll to do a union of existing set.
使用retain all,remove all 然后addAll 来做现有集合的并集。
- intersectionSet.retainAll(set2) // intersectionSet is a copy of set1
- set1.addAll(set2); // do a union of set1 and set2
- then remove the duplicates set1.removeAll(intersectionSet);
- 交集集.retainAll(集2) //交集集是集1的副本
- set1.addAll(set2); // 对 set1 和 set2 进行并集
- 然后删除重复项 set1.removeAll(intersectionSet);
回答by Chandra Sekhar
Set<String> s1 = new HashSet<String>();
Set<String> s2 = new HashSet<String>();
s1.add("a");
s1.add("b");
s2.add("b");
s2.add("c");
Set<String> s3 = new HashSet<String>(s1);
s1.removeAll(s2);
s2.removeAll(s3);
s1.addAll(s2);
System.out.println(s1);
output of s1 : [a,c]
s1 的输出：[a,c]
回答by beny23
You could use CollectionUtils#disjunction
你可以用 CollectionUtils#disjunction
EDIT:
编辑：
Alternatively with less pre-Java-5-ness, use Guava Sets#symmetricDifference
或者，使用较少的前 Java-5-ness，使用 Guava Sets#symmetricDifference
回答by jameshfisher
Those looking for set subtraction/complement(not symmetric difference/disjunction) can use CollectionUtils.subtract(a,b)or Sets.difference(a,b).
那些寻找集合减法/补码（非对称差/析取）的人可以使用CollectionUtils.subtract(a,b)或Sets.difference(a,b)。
回答by Donald Raab
You could try Sets.symmetricDifference()from Eclipse Collections.
您可以Sets.symmetricDifference()从Eclipse Collections尝试。
Set<Integer> set1 = new TreeSet<>(Arrays.asList(501,502,503,504));
Set<Integer> set2 = new TreeSet<>(Arrays.asList(502,503,504,505));
Set<Integer> symmetricDifference =
Sets.symmetricDifference(set1, set2);
Assert.assertEquals(
new TreeSet<>(Arrays.asList(501, 505)),
symmetricDifference);
Note: I am a committer for Eclipse Collections.
注意：我是 Eclipse Collections 的提交者。
回答by dobrivoje
if we use package com.google.common.collect, we may ellegantly find symmetric difference like this :
如果我们使用 com.google.common.collect 包，我们可能会优雅地找到这样的对称差异：
Set<Integer> s1 = Stream.of( 1,2,3,4,5 ).collect( Collectors.toSet());
Set<Integer> s2 = Stream.of( 2,3,4 ).collect( Collectors.toSet());
System.err.println(Sets.symmetricDifference( s1,s2 ));
The output will be : [1, 5]
输出将是：[1, 5]
