A KeyValuePair in Java | 易学教程

问题

I'm looking for a KeyValuePair class in Java.
Since java.util heavily uses interfaces there is no concrete implementation provided, only the Map.Entry interface.

Is there some canonical implementation I can import? It is one of those "plumbers programming" classes I hate to implement 100x times.

回答1:

The documentation AbstractMap.SimpleEntry is generic and can be useful.

回答2:

Android programmers could use BasicNameValuePair

Update:

BasicNameValuePair is now deprecated (API 22). Use Pair instead.

Example usage:

Pair<Integer, String> simplePair = new Pair<>(42, "Second");
Integer first = simplePair.first; // 42
String second = simplePair.second; // "Second"

回答3:

The Pair class from Commons Lang might help:

Pair<String, String> keyValue = new ImmutablePair("key", "value");

Of course, you would need to include commons-lang.

回答4:

Use of javafx.util.Pair is sufficient for most simple Key-Value pairings of any two types that can be instantiated.

Pair<Integer, String> myPair = new Pair<>(7, "Seven");
Integer key = myPair.getKey();
String value = myPair.getValue();

回答5:

import java.util.Map;

public class KeyValue<K, V> implements Map.Entry<K, V>
{
    private K key;
    private V value;

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

    public K getKey()
    {
        return this.key;
    }

    public V getValue()
    {
        return this.value;
    }

    public K setKey(K key)
    {
        return this.key = key;
    }

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

回答6:

I like to use

Properties

Example:

Properties props = new Properties();

props.setProperty("displayName", "Jim Wilson"); // (key, value)

String name = props.getProperty("displayName"); // => Jim Wilson

String acctNum = props.getProperty("accountNumber"); // => null

String nextPosition = props.getProperty("position", "1"); // => 1

If you are familiar with a hash table you will be pretty familiar with this already

回答7:

I've published a NameValuePair class in GlobalMentor's core library, available in Maven. This is an ongoing project with a long history, so please submit any request for changes or improvements.

回答8:

My favorite is

HashMap<Type1, Type2>

All you have to do is specify the datatype for the key for Type1 and the datatype for the value for Type2. It's the most common key-value object I've seen in Java.

https://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html

回答9:

Hashtable<String, Object>

It is better than java.util.Properties which is by fact an extension of Hashtable<Object, Object>.

来源：https://stackoverflow.com/questions/2973041/a-keyvaluepair-in-java

标签

java

key-value