--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/awt/SecondaryLoop.java Tue Aug 24 12:54:46 2010 +0400
@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2010, 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 java.awt;
+
+/**
+ * A helper interface to run the nested event loop.
+ * <p>
+ * Objects that implement this interface are created with the
+ * {@link EventQueue#createSecondaryLoop} method. The interface
+ * provides two methods, {@link enter} and {@link exit},
+ * which can be used to start and stop the event loop.
+ * <p>
+ * When the {@link enter} method is called, the current
+ * thread is blocked until the loop is terminated by the
+ * {@link exit} method. Also, a new event loop is started
+ * on the event dispatch thread, which may or may not be
+ * the current thread. The loop can be terminated on any
+ * thread by calling its {@link exit} method. After the
+ * loop is terminated, the {@code SecondaryLoop} object can
+ * be reused to run a new nested event loop.
+ * <p>
+ * A typical use case of applying this interface is AWT
+ * and Swing modal dialogs. When a modal dialog is shown on
+ * the event dispatch thread, it enters a new secondary loop.
+ * Later, when the dialog is hidden or disposed, it exits
+ * the loop, and the thread continues its execution.
+ * <p>
+ * The following example illustrates a simple use case of
+ * secondary loops:
+ *
+ * <pre>
+ * SecondaryLoop loop;
+ *
+ * JButton jButton = new JButton("Button");
+ * jButton.addActionListener(new ActionListener() {
+ * {@code @Override}
+ * public void actionPerformed(ActionEvent e) {
+ * Toolkit tk = Toolkit.getDefaultToolkit();
+ * EventQueue eq = tk.getSystemEventQueue();
+ * loop = eq.createSecondaryLoop();
+ *
+ * // Spawn a new thread to do the work
+ * Thread worker = new WorkerThread();
+ * worker.start();
+ *
+ * // Enter the loop to block the current event
+ * // handler, but leave UI responsive
+ * if (!loop.enter()) {
+ * // Report an error
+ * }
+ * }
+ * });
+ *
+ * class WorkerThread extends Thread {
+ * {@code @Override}
+ * public void run() {
+ * // Perform calculations
+ * doSomethingUseful();
+ *
+ * // Exit the loop
+ * loop.exit();
+ * }
+ * }
+ * </pre>
+ *
+ * @see Dialog#show
+ * @see EventQueue#createSecondaryLoop
+ * @see Toolkit#getSystemEventQueue
+ *
+ * @author Anton Tarasov, Artem Ananiev
+ *
+ * @since 1.7
+ */
+public interface SecondaryLoop {
+
+ /**
+ * Blocks the execution of the current thread and enters a new
+ * secondary event loop on the event dispatch thread.
+ * <p>
+ * This method can be called by any thread including the event
+ * dispatch thread. This thread will be blocked until the {@link
+ * exit} method is called or the loop is terminated. A new
+ * secondary loop will be created on the event dispatch thread
+ * for dispatching events in either case.
+ * <p>
+ * This method can only start one new event loop at a time per
+ * object. If a secondary event loop has already been started
+ * by this object and is currently still running, this method
+ * returns {@code false} to indicate that it was not successful
+ * in starting a new event loop. Otherwise, this method blocks
+ * the calling thread and later returns {@code true} when the
+ * new event loop is terminated. At such time, this object can
+ * again be used to start another new event loop.
+ *
+ * @return {@code true} after termination of the secondary loop,
+ * if the secondary loop was started by this call,
+ * {@code false} otherwise
+ */
+ public boolean enter();
+
+ /**
+ * Unblocks the execution of the thread blocked by the {@link
+ * enter} method and exits the secondary loop.
+ * <p>
+ * This method resumes the thread that called the {@link enter}
+ * method and exits the secondary loop that was created when
+ * the {@link enter} method was invoked.
+ * <p>
+ * Note that if any other secondary loop is started while this
+ * loop is running, the blocked thread will not resume execution
+ * until the nested loop is terminated.
+ * <p>
+ * If this secondary loop has not been started with the {@link
+ * enter} method, or this secondary loop has already finished
+ * with the {@link exit} method, this method returns {@code
+ * false}, otherwise {@code true} is returned.
+ *
+ * @return {@code true} if this loop was previously started and
+ * has not yet been finished with the {@link exit} method,
+ * {@code false} otherwise
+ */
+ public boolean exit();
+
+}