KeyValuePair.java

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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * The MIT License
 *
 * Copyright (c) 2004-2015 Paul R. Holser, Jr.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package jdk.internal.joptsimple.util;

import static jdk.internal.joptsimple.internal.Strings.*;

/**
 * <p>A simple string key/string value pair.</p>
 *
 * <p>This is useful as an argument type for options whose values take on the form {@code key=value}, such as JVM
 * command line system properties.</p>
 *
 * @author <a href="mailto:[email protected]">Paul Holser</a>
 */
public final class KeyValuePair {
    public final String key;
    public final String value;

    private KeyValuePair( String key, String value ) {
        this.key = key;
        this.value = value;
    }

    /**
     * Parses a string assumed to be of the form {@code key=value} into its parts.
     *
     * @param asString key-value string
     * @return a key-value pair
     * @throws NullPointerException if {@code stringRepresentation} is {@code null}
     */
    public static KeyValuePair valueOf( String asString ) {
        int equalsIndex = asString.indexOf( '=' );
        if ( equalsIndex == -1 )
            return new KeyValuePair( asString, null );

        String aKey = asString.substring( 0, equalsIndex );
        String aValue = equalsIndex == asString.length() - 1 ? EMPTY : asString.substring( equalsIndex + 1 );

        return new KeyValuePair( aKey, aValue );
    }

    @Override
    public boolean equals( Object that ) {
        if ( !( that instanceof KeyValuePair ) )
            return false;

        KeyValuePair other = (KeyValuePair) that;
        return key.equals( other.key ) && value.equals( other.value );
    }

    @Override
    public int hashCode() {
        return key.hashCode() ^ value.hashCode();
    }

    @Override
    public String toString() {
        return key + '=' + value;
    }
}