2

我正在尝试删除链表中的一项。

private LinkedList<Item> items = new LinkedList<>();

items.add(new Item("Movie1", "2010", "2"));
items.add(new Item("Movie1", "2010", "2"));

我尝试检查该项目是否存在于列表中。

如果该项目存在，则删除该项目。

只是它删除了所有项目。

我只想删除一项所以，结果应该是在删除之后。

[Movie1, 2010, 2];

有什么办法可以做到吗？

谢谢。

4

2 回答 2

1

使用删除（整数索引）

import java.util.LinkedList;
import java.util.Objects;

class Item {
    String name, year, id;

    public Item(String name, String year, String id) {
        this.name = name;
        this.year = year;
        this.id = id;
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, year, id);
    }

    @Override
    public boolean equals(Object obj) {
        Item other = (Item) obj;
        return this.name.equals(other.name) && this.year.equals(other.year) && this.id.equals(other.id);
    }

    @Override
    public String toString() {
        return "Name: " + name + ", Year: " + year + ", ID: " + id;
    }
}

public class Main {
    public static void main(String[] args) {
        LinkedList<Item> items = new LinkedList<Item>();
        Item item1 = new Item("Movie1", "2010", "2");
        Item item2 = new Item("Movie2", "2020", "3");
        items.add(item1);
        items.add(item1);
        items.add(item2);
        System.out.println("Before: ");
        System.out.println(items);

        remove(items, item1);
        remove(items, item2);

        System.out.println("After: ");
        System.out.println(items);

        // Trying to remove item1 again
        remove(items, item1);
        System.out.println("Result: ");
        System.out.println(items);
    }

    /**
     * If list contains more than one occurrence of item, removes the first
     * occurrence of item from list
     * 
     * @param items from which the first occurrence of item has to be removed
     * @param item
     */
    static void remove(LinkedList<Item> items, Item item) {
        for (int i = 0; i < items.size(); i++) {
            if (items.get(i).equals(item)) {
                if (items.subList(i + 1, items.size()).contains(items.get(i))) {
                    items.remove(i);
                    break;
                }
            }
        }
    }
}

输出：

Before: 
[Name: Movie1, Year: 2010, ID: 2, Name: Movie1, Year: 2010, ID: 2, Name: Movie2, Year: 2020, ID: 3]
After: 
[Name: Movie1, Year: 2010, ID: 2, Name: Movie2, Year: 2020, ID: 3]
Result: 
[Name: Movie1, Year: 2010, ID: 2, Name: Movie2, Year: 2020, ID: 3]
于 2020-05-05T12:56:35.773 回答
0

您也可以使用 list Collections contains 方法，然后将其删除。

Item item1 = new Item("Movie1", "2010", "2");
if(items.contains(item1){
  items.remove(item1)
}

此外，要使上述代码正常工作，您需要覆盖 Item POJO 中的 hashcode 和 equals 方法。

于 2020-05-05T13:25:13.177 回答