https://openjdk.java.net/ 
/*
 * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.jdi.event;

import com.sun.jdi.ThreadReference;
import com.sun.jdi.VirtualMachine;


Notification of a new running thread in the target VM.
The new thread can be the result of a call to
Thread.start or the result of attaching a new thread to the VM though JNI. The notification is generated by the new thread some time before its execution starts. Because of this timing, it is possible to receive other events for the thread before this event is received. (Notably, MethodEntryEvents and MethodExitEvents might occur during thread initialization.) It is also possible for VirtualMachine.allThreads to return a new started thread before this event is received. 

Note that this event gives no information
about the creation of the thread object which may have happened
much earlier, depending on the VM being debugged.

Author:Robert Field
See Also:
Since: 1.3
/**
 * Notification of a new running thread in the target VM.
 * The new thread can be the result of a call to
 * <code>{@link java.lang.Thread#start}</code> or the result of
 * attaching a new thread to the VM though JNI. The
 * notification is generated by the new thread some time before
 * its execution starts.
 * Because of this timing, it is possible to receive other events
 * for the thread before this event is received. (Notably,
 * {@link MethodEntryEvent}s and {@link MethodExitEvent}s might occur
 * during thread initialization.)
 * It is also possible for {@link VirtualMachine#allThreads} to return
 * a new started thread before this event is received.
 * <p>
 * Note that this event gives no information
 * about the creation of the thread object which may have happened
 * much earlier, depending on the VM being debugged.
 *
 * @see EventQueue
 * @see VirtualMachine
 * @see ThreadReference
 *
 * @author Robert Field
 * @since  1.3
 */
public interface ThreadStartEvent extends Event {

    
Returns the thread which has started.

Returns:a ThreadReference which mirrors the event's thread in the target VM.
/**
     * Returns the thread which has started.
     *
     * @return a {@link ThreadReference} which mirrors the event's thread in
     * the target VM.
     */
    public ThreadReference thread();
}