Threads - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 273

public class DataSyncApplet extends JApplet
implements Outputable, ActionListener
{
. ..Build the interface...
/** Create Sensor and DataGetter thread instances and
* start them filling and getting from a Box instance.
**/
public void start() {
// Create the Sensor and start it
Sensor s = new Sensor (this);
s.start ();
// Create DataGetter and tell it to obtain
// 100 sensor readings.
DataGetter dg = new DataGetter (s, 100, this);
dg.start ();
} // start
...
} // class DataSyncApplet
The Sensor (see code below) produces one data value (just a string containing
the number of milliseconds since the program began) and stores it in an ele-
ment of a buffer array. The fBufIndex keeps track of where the next value
should go. When it reaches the end of the array, it will circle back to the start.
The fGetIndex marks the value in the buffer that will be sent next to the
DataGetter . The fGetIndex should never fall farther behind fBufIndex
than the MAXGAP value (set here to 8). If the lag reaches the value of fMaxGap
then the sensor goes into a loop with an invocation of wait() for each pass.
When the DataGetter invokes the get() method, the notifyAll() will
wake the Sensor thread from its wait state and it will check the lag again. If it is
no longer at the maximum, the process leaves the wait loop and produces more
data. Otherwise, it loops back around and invokes wait() again.
import java.util.*;
/**
* This class represents a sensor producing data
* that the DataGetter objects want to read.
*/
public class Sensor extends Thread
{
// Size of the data buffer.
private static final int BUFFER - SIZE = 10;