EventObject.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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package java.util;

/**
 * <p>
 * The root class from which all event state objects shall be derived.
 * <p>
 * All Events are constructed with a reference to the object, the "source",
 * that is logically deemed to be the object upon which the Event in question
 * initially occurred upon.
 *
 * @since 1.1
 */

public class EventObject implements java.io.Serializable {

    @java.io.Serial
    private static final long serialVersionUID = 5516075349620653480L;

    /**
     * The object on which the Event initially occurred.
     */
    protected transient Object source;

    /**
     * Constructs a prototypical Event.
     *
     * @param source the object on which the Event initially occurred
     * @throws IllegalArgumentException if source is null
     */
    public EventObject(Object source) {
        if (source == null)
            throw new IllegalArgumentException("null source");

        this.source = source;
    }

    /**
     * The object on which the Event initially occurred.
     *
     * @return the object on which the Event initially occurred
     */
    public Object getSource() {
        return source;
    }

    /**
     * Returns a String representation of this EventObject.
     *
     * @return a String representation of this EventObject
     */
    public String toString() {
        return getClass().getName() + "[source=" + source + "]";
    }
}