Java中set集合

两个集合{"a","b","c","d","e"},{"d","e","f","g","h"}合并成一个集合,并且去掉重复的

Set可以自动去重，所以使用Set直接添加数据就可以。

public static void main(String[] args) {
    List<String> strList1 = new ArrayList<>(Arrays.asList("a", "b", "c", "d", "e"));
    List<String> strList2 = new ArrayList<>(Arrays.asList("d", "e", "f", "g", "h"));
    // 创建set并将strList1集合数据赋给set
    Set<String> set = new HashSet<>(strList1);
    // 将strList2集合合并到set
    for (String str : strList2) {
        set.add(str);
    }
    System.out.println("合并后：" + set);
}

直接用Set就行了


//Set集合
    public static void main(String[] args) {
        String[] str1={"a","b","c","d","e"};
        String[] str2={"d","e","f","g","h"};
        
        Set set1 = new HashSet(Arrays.asList(str1));
        Set set2 = new HashSet(Arrays.asList(str2));
        Set set = new HashSet();
        
        // 并集
        set.addAll(set1);
        set.addAll(set2);
        System.out.println("并集" + set);

        // 交集
        set.clear();
        set.addAll(set1);
        set.retainAll(set2);
        System.out.println("交集" + set);
        // 差集
        set.clear();
        set.addAll(set1);
        set.removeAll(set2);
        System.out.println("差集" + set);    
        }



    //List集合
 public static void main(String[] args) {
        String[] str1 = { "a", "b", "c", "d", "e" };
        String[] str2 = { "d", "e", "f", "g", "h" };
        ArrayList list1 = new ArrayList(Arrays.asList(str1));
        ArrayList list2 = new ArrayList(Arrays.asList(str2));
        ArrayList list = new ArrayList();
        // 并集
        list.addAll(list1);
        for (int i = 0; i < list2.size(); i++) {
            if (!list.contains(list2.get(i)))
                list.add(list2.get(i));
        }
        System.out.println("并集" + list);

        // 交集
        list.clear();
        for (int i = 0; i < list2.size(); i++) {
            if (list1.contains(list2.get(i)))
                list.add(list2.get(i));
        }
        System.out.println("交集" + list);

        // 差集
        list.clear();
        for (int i = 0; i < list1.size(); i++) {
            if (!list2.contains(list1.get(i)))
                list.add(list1.get(i));
        }
        System.out.println("差集" + list);
    }




import java.util.Arrays;
import java.util.HashSet;

/**
 * @author yangbocsu
 * @create 2022/06/18
 * @projectName test1
 */

public class Solution {
    public static void main(String[] args) {
        //{"a","b","c","d","e"};//,{"d","e","f","g","h"}
        HashSet<String> set1 = new HashSet<>(Arrays.asList("a", "b", "c", "d", "e"));
        HashSet<String> set2 = new HashSet<>(Arrays.asList("d", "e", "f", "g", "h"));
        System.out.println("set1: "+set1);
        System.out.println("set2: "+set2);
        // 把set2 合并到set1
        for(String i : set2){
            // 如果set1中没有 i(set2中的元素)，就加入到set1中
            if (!set1.contains(i)){
                set1.add(i);
            }
        }
        System.out.println("合并后："+set1);
    }
}

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