Pair.java

package org.ggp.base.util;

import java.util.Map;

public class Pair <L, R> {
    public final L left;
    public final R right;

    private Pair(L left, R right) {
        this.left = left;
        this.right = right;
    }

    public static <L, R> Pair<L, R> of(L left, R right) {
        return new Pair<L, R>(left, right);
    }

    public static <L, R> Pair<L, R> from(Map.Entry<L, R> entry) {
        return of(entry.getKey(), entry.getValue());
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((left == null) ? 0 : left.hashCode());
        result = prime * result + ((right == null) ? 0 : right.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Pair<?, ?> other = (Pair<?, ?>) obj;
        if (left == null) {
            if (other.left != null)
                return false;
        } else if (!left.equals(other.left))
            return false;
        if (right == null) {
            if (other.right != null)
                return false;
        } else if (!right.equals(other.right))
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "<" + left + ", " + right + ">";
    }
}