Pausing and Running the Animation

• Want to pause animation until "Run" or "Step" button is clicked
• Need to coordinate UI thread, animation thread
• Try to use built-in thread-safe construct in java.util.concurrent
• Trick: Use a blocking queue
• Button click adds string "Run" or "Step" to queue
• Animation thread calls take on the queue, blocks if no string inserted
• Sorter.java
• AnimationTester.java