Pair.java

package org.neo4j.helpers;


/**
 * Utility to handle pairs of objects.
 */
public class Pair<T1, T2>
{
    private final T1 first;
    private final T2 other;

    /**
     * Create a new pair of objects.
     *
     * @param first the first object in the pair.
     * @param other the other object in the pair.
     */
    public Pair( T1 first, T2 other )
    {
        this.first = first;
        this.other = other;
    }

    public static <T1, T2> Pair<T1, T2> of( T1 first, T2 other )
    {
        return new Pair<T1, T2>( first, other );
    }

    /**
     * @return the first object in the pair.
     */
    public T1 first()
    {
        return first;
    }

    /**
     * @return the other object in the pair.
     */
    public T2 other()
    {
        return other;
    }

    @Override
    public String toString()
    {
        return "(" + first + ", " + other + ")";
    }

    @Override
    public int hashCode()
    {
        return ( 31 * hashCode( first ) ) | hashCode( other );
    }

    @SuppressWarnings( "unchecked" )
    @Override
    public boolean equals( Object obj )
    {
        if ( this == obj ) return true;
        if ( obj instanceof Pair )
        {
            if ( obj.getClass() != this.getClass() ) return false;
            return pairEquals( (Pair) obj );
        }
        return false;
    }

    boolean pairEquals( Pair that )
    {
        return equals( this.first, that.first ) && equals( this.other, that.other );
    }

    static int hashCode( Object obj )
    {
        return obj == null ? 0 : obj.hashCode();
    }

    static boolean equals( Object obj1, Object obj2 )
    {
        return ( obj1 == obj2 ) || ( obj1 != null && obj1.equals( obj2 ) );
    }
}