HashMap兼容Pair类:

public class Pair<A, B> {
    private A first;
    private B second;

    public Pair(A first, B second) {
        super();
        this.first = first;
        this.second = second;
    }

    public int hashCode() {
        int hashFirst = first != null ? first.hashCode() : 0;
        int hashSecond = second != null ? second.hashCode() : 0;

        return (hashFirst + hashSecond) * hashSecond + hashFirst;
    }

    public boolean equals(Object other) {
        if (other instanceof Pair) {
            Pair otherPair = (Pair) other;
            return 
            ((  this.first == otherPair.first ||
                ( this.first != null && otherPair.first != null &&
                  this.first.equals(otherPair.first))) &&
             (  this.second == otherPair.second ||
                ( this.second != null && otherPair.second != null &&
                  this.second.equals(otherPair.second))) );
        }

        return false;
    }

    public String toString()
    { 
           return "(" + first + ", " + second + ")"; 
    }

    public A getFirst() {
        return first;
    }

    public void setFirst(A first) {
        this.first = first;
    }

    public B getSecond() {
        return second;
    }

    public void setSecond(B second) {
        this.second = second;
    }
}

简单的方法Object[] -可以作为一个几何体元组使用

android提供了Pairclass (http://developer.android.com/reference/android/util/Pair.html)，这里实现:

public class Pair<F, S> {
    public final F first;
    public final S second;

    public Pair(F first, S second) {
        this.first = first;
        this.second = second;
    }

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof Pair)) {
            return false;
        }
        Pair<?, ?> p = (Pair<?, ?>) o;
        return Objects.equal(p.first, first) && Objects.equal(p.second, second);
    }

    @Override
    public int hashCode() {
        return (first == null ? 0 : first.hashCode()) ^ (second == null ? 0 : second.hashCode());
    }

    public static <A, B> Pair <A, B> create(A a, B b) {
        return new Pair<A, B>(a, b);
    }
}

根据Java语言的性质，我认为人们实际上并不需要Pair，通常他们需要的是一个接口。这里有一个例子:

interface Pair<L, R> {
    public L getL();
    public R getR();
}

所以，当人们想要返回两个值时，他们可以这样做:

... //Calcuate the return value
final Integer v1 = result1;
final String v2 = result2;
return new Pair<Integer, String>(){
    Integer getL(){ return v1; }
    String getR(){ return v2; }
}

This is a pretty lightweight solution, and it answers the question "What is the semantic of a Pair<L,R>?". The answer is, this is an interface build with two (may be different) types, and it has methods to return each of them. It is up to you to add further semantic to it. For example, if you are using Position and REALLY want to indicate it in you code, you can define PositionX and PositionY that contains Integer, to make up a Pair<PositionX,PositionY>. If JSR 308 is available, you may also use Pair<@PositionX Integer, @PositionY Ingeger> to simplify that.

编辑: 这里我应该指出的一点是，上面的定义显式地将类型参数名和方法名联系起来。这是对那些认为Pair缺乏语义信息的人的回答。实际上，getL方法的意思是“给我对应于类型参数L的类型的元素”，这确实意味着什么。

编辑: 下面是一个简单的实用程序类，可以让生活变得更简单:

class Pairs {
    static <L,R> Pair<L,R> makePair(final L l, final R r){
        return new Pair<L,R>(){
            public L getL() { return l; }
            public R getR() { return r; }   
        };
    }
}

用法:

return Pairs.makePair(new Integer(100), "123");

这取决于你想用它来做什么。这样做的典型原因是在地图上迭代，为此你可以简单地这样做(Java 5+):

Map<String, Object> map = ... ; // just an example
for (Map.Entry<String, Object> entry : map.entrySet()) {
  System.out.printf("%s -> %s\n", entry.getKey(), entry.getValue());
}

虽然这个问题已经有十多年的历史了，但我觉得有必要提一下，从Java 14开始，Records可以为这个问题提供非常简单和轻量级的解决方案，而不需要任何形式的外部库或依赖项。

例如，以下记录类声明将是实现所需功能所需的全部内容:

record Pair<K, V>(K key, V value) { }

这样一个记录类可以这样使用:

// Declare a pair object containing two integers
var integerIntegerPair = new Pair<>(1, 2);

// Declare a pair object containing a String and an integer
var stringIntegerPair = new Pair<>("String", 20);

// Declare a pair object containing two other pairs!
var pairPairPair = new Pair<>(new Pair<>(1, 2), new Pair<>("String", 20));