在Java中使用对或2元组[重复]

曾经终败给现在 2022-11-28 13:57 28阅读 0赞

本文翻译自：[Using Pairs or 2-tuples in Java \[duplicate\]][Using Pairs or 2-tuples in Java _duplicate]

*This question already has an answer here:* **这个问题在这里已有答案：**

*  *A Java collection of value pairs?* **价值对的Java集合？** *(tuples?) 19 answers* **（元组？） 19个答案**

*My Hashtable in Java would benefit from a value having a tuple structure.* **Java中的Hashtable将受益于具有元组结构的值。** *What data structure can I use in Java to do that?* **我可以在Java中使用哪种数据结构来做到这一点？**

Hashtable<Long, Tuple<Set<Long>,Set<Long>>> table = ...

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### \#1楼 ###

参考：[https://stackoom.com/question/bcQm/在Java中使用对或-元组-重复][https_stackoom.com_question_bcQm_Java_-_-]

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### \#2楼 ###

*[javatuples][] is a dedicated project for tuples in Java.* **[javatuples][]是Java [中元][javatuples]组的专用项目。**

Unit<A> (1 element)
    Pair<A,B> (2 elements)
    Triplet<A,B,C> (3 elements)

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### \#3楼 ###

*As an extension to @maerics nice answer, I've added a few useful methods:* **作为@maerics很好的答案的扩展，我添加了一些有用的方法：**

public class Tuple<X, Y> { 
        public final X x; 
        public final Y y; 
        public Tuple(X x, Y y) { 
            this.x = x; 
            this.y = y; 
        }
    
        @Override
        public String toString() {
            return "(" + x + "," + y + ")";
        }
    
        @Override
        public boolean equals(Object other) {
            if (other == this) {
                return true;
            }
    
            if (!(other instanceof Tuple)){
                return false;
            }
    
            Tuple<X,Y> other_ = (Tuple<X,Y>) other;
    
            // this may cause NPE if nulls are valid values for x or y. The logic may be improved to handle nulls properly, if needed.
            return other_.x.equals(this.x) && other_.y.equals(this.y);
        }
    
        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + ((x == null) ? 0 : x.hashCode());
            result = prime * result + ((y == null) ? 0 : y.hashCode());
            return result;
        }
    }

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### \#4楼 ###

*To supplement @maerics's answer, here is the `Comparable` tuple:* **为了补充@ maerics的答案，这里是`Comparable`元组：**

import java.util.*;
    
    /**
     * A tuple of two classes that implement Comparable
     */
    public class ComparableTuple<X extends Comparable<? super X>, Y extends Comparable<? super Y>>
           extends Tuple<X, Y>
           implements Comparable<ComparableTuple<X, Y>>
    {
      public ComparableTuple(X x, Y y) {
        super(x, y);
      }
    
      /**
       * Implements lexicographic order
       */
      public int compareTo(ComparableTuple<X, Y> other) {
        int d = this.x.compareTo(other.x);
        if (d == 0)
          return this.y.compareTo(other.y);
        return d;
      }
    }

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### \#5楼 ###

如果您正在寻找内置的Java双元素元组，请尝试使用`AbstractMap.SimpleEntry` 。

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### \#6楼 ###

*[Apache Commons][] provided some common java utilities including a [Pair][] .* **[Apache Commons][]提供了一些常见的Java实用程序，包括一[对][Pair] 。** *It implements `Map.Entry` , `Comparable` and `Serializable` .* **它实现了`Map.Entry` ， `Comparable`和`Serializable` 。**

[Using Pairs or 2-tuples in Java _duplicate]: https://oldbug.net/q/bcQm/Using-Pairs-or-2-tuples-in-Java-duplicate
[https_stackoom.com_question_bcQm_Java_-_-]: https://stackoom.com/question/bcQm/%E5%9C%A8Java%E4%B8%AD%E4%BD%BF%E7%94%A8%E5%AF%B9%E6%88%96-%E5%85%83%E7%BB%84-%E9%87%8D%E5%A4%8D
[javatuples]: http://www.javatuples.org/
[Apache Commons]: http://commons.apache.org/
[Pair]: http://commons.apache.org/proper/commons-lang/javadocs/api-3.1/org/apache/commons/lang3/tuple/package-summary.html