Java - 如何创建新条目(键、值) [英] Java - How to create new Entry (key, value)

问题描述

我想创建类似于 Util.Map.Entry 的新项目，它将包含结构 key, value.

I'd like to create new item that similarly to Util.Map.Entry that will contain the structure key, value.

问题是我无法实例化 Map.Entry 因为它是一个接口.

The problem is that I can't instantiate a Map.Entry because it's an interface.

有谁知道如何为 Map.Entry 创建一个新的通用键/值对象?

Does anyone know how to create a new generic key/value object for Map.Entry?

推荐答案

你可以自己实现 Map.Entry 接口:

You can just implement the Map.Entry<K, V> interface yourself:

import java.util.Map;

final class MyEntry<K, V> implements Map.Entry<K, V> {
    private final K key;
    private V value;

    public MyEntry(K key, V value) {
        this.key = key;
        this.value = value;
    }

    @Override
    public K getKey() {
        return key;
    }

    @Override
    public V getValue() {
        return value;
    }

    @Override
    public V setValue(V value) {
        V old = this.value;
        this.value = value;
        return old;
    }
}

然后使用它:

Map.Entry<String, Object> entry = new MyEntry<String, Object>("Hello", 123);
System.out.println(entry.getKey());
System.out.println(entry.getValue());

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