java中List集合去重常见的几种方法总结

import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;

public class ListDeduplication {
    public static <T> List<T> deduplicateUsingLinkedHashSet(List<T> list) {
        return new ArrayList<>(new LinkedHashSet<>(list));
    }

    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        list.add(1);
        list.add(2);
        list.add(2);
        list.add(3);
        list.add(4);
        list.add(4);
        List<Integer> deduplicatedList = deduplicateUsingLinkedHashSet(list);
        System.out.println(deduplicatedList);
    }
}

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class ListDeduplicationWithStream {
    public static <T> List<T> deduplicateUsingStream(List<T> list) {
        return list.stream().distinct().collect(Collectors.toList());
    }

    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        list.add(1);
        list.add(2);
        list.add(2);
        list.add(3);
        list.add(4);
        list.add(4);
        List<Integer> deduplicatedList = deduplicateUsingStream(list);
        System.out.println(deduplicatedList);
    }
}

import java.util.ArrayList;
import java.util.List;

public class ManualListDeduplication {
    public static <T> List<T> deduplicateManually(List<T> list) {
        List<T> result = new ArrayList<>();
        for (T item : list) {
            if (!result.contains(item)) {
                result.add(item);
            }
        }
        return result;
    }

    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        list.add(1);
        list.add(2);
        list.add(2);
        list.add(3);
        list.add(4);
        list.add(4);
        List<Integer> deduplicatedList = deduplicateManually(list);
        System.out.println(deduplicatedList);
    }
}