java的set

目錄

1.HashSet

2.TreeSet

4.set排序

1.HashSet

import java.util.*;

public class set {
    public static void main(String args[]){
        HashSet<Integer> set = new HashSet<Integer>(0);
        //增加
        set.add(5);
        set.add(6);
        set.add(4);
        set.add(100);//[4, 100, 5, 6]
        //刪除
        set.remove(100);//[4, 5, 6]
        List<Integer> list1 = new ArrayList<>();
        list1.add(5);list1.add(6);
        set.removeAll(list1);//[4]
        //查尋
        set.add(6);
        set.add(4);
        set.add(100);//[4, 100, 6]
        Boolean contains = set.contains(4);//true
        Boolean isEmpty = set.isEmpty();//false
        int size = set.size();//3
        //複製
        HashSet<Integer> set1 = new HashSet<Integer>(0);
        set1 = set;
        System.out.println(set1);//[4, 100, 6]
        set1.add(99);
        System.out.println(set);//[99, 4, 100, 6]
        System.out.println(set1);//[99, 4, 100, 6]
        Object set2 = new Object();
        set2 = set.clone();
        System.out.println(set2);//[99, 4, 100, 6]
        //遍歷
        set.remove(99);
        Iterator<Integer> it = set.iterator();
        while (it.hasNext()) {
            Integer s = it.next();
            System.out.print(s);//41006
        }
        System.out.print("\n");
        for (Integer n : set) {
            System.out.print(n);//41006
        }

    }
}

2.TreeSet

import java.util.*;

public class set {
    public static void main(String args[]){
        TreeSet<Integer> set = new TreeSet<Integer>();
        //增加
        set.add(5);
        List<Integer> list = new ArrayList<>();
        list.add(6);list.add(4);
        set.addAll(list);
        set.add(100);//[4, 5, 6, 100]
        //刪除
        set.remove(100);//[4, 5, 6]
        List<Integer> list1 = new ArrayList<>();
        list1.add(5);list1.add(6);
        set.removeAll(list1);//[4]
        set.addAll(list1);
        list1.clear();
        list1.add(4);
        set.retainAll(list1);//[4]
        //修改和刪除
        set.add(1);
        set.add(100);
        Integer pollFirst = set.pollFirst();//1
        Integer polllast = set.pollLast();//100
        System.out.println(set);//[4]
        //查尋
        set.add(6);
        set.add(4);
        set.add(100);//[4, 100, 6]
        Boolean contains = set.contains(4);//true
        Boolean isEmpty = set.isEmpty();//false
        int size = set.size();//3
        List<Integer> list2 = new ArrayList<>();
        list2.add(6);list2.add(4);
        Boolean containsAll = set.containsAll(list2);//true
        int first = set.first();//4
        int last = set.last();//100
        //複製
        TreeSet<Integer> set1 = new TreeSet<Integer>();
        set1 = set;
        //System.out.println(set1);//[4, 6, 100]
        set1.add(99);
        //System.out.println(set);//[4, 6, 99, 100]
        //System.out.println(set1);//[4, 6, 99, 100]
        //獲取子set
        SortedSet<Integer> subSet = set.subSet(6,99);//[6]
        SortedSet<Integer> tailSet = set.tailSet(6);//[6, 99, 100]
        //遍歷
        set.remove(99);
        Iterator<Integer> it = set.iterator();
        while (it.hasNext()) {
            Integer s = it.next();
            System.out.print(s);//46100
        }
        System.out.print("\n");
        for (Integer n : set) {
            System.out.print(n);//46100
        }

    }
}

 

4.set排序

import java.util.*;

public class set {
    public static void main( String[] args ) {
        Set<String> set = new HashSet<>();
        set.add("1");
        set.add("3");
        set.add("2");
        set.add("4");
        set.add("5");

        Set<String> sortSet = new TreeSet<String>(new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                return o2.compareTo(o1);//降序排列
            }
        });
        //Set<String> sortSet = new TreeSet<String>((o1, o2) -> o2.compareTo(o1));
        System.out.println(set);//[1, 2, 3, 4, 5]
        System.out.println(sortSet);//[]
        sortSet.addAll(set);
        System.out.println(sortSet);//[5, 4, 3, 2, 1]

    }
}