This class keeps the output of a double solenoid valve energized for a specified duration after it's state has changed. After the energized duration has elapsed, the solenoid is de-energized.

MomentaryDoubleSolenoid.java

package org.team2168.utils;

import edu.wpi.first.wpilibj.DoubleSolenoid;
import java.util.Timer;
import java.util.TimerTask;

/**
* This class keeps the output of a double solenoid valve energized
* for a specified duration after it's state has changed. After the
* energized duration has elapsed, the solenoid is de-energized.
*
* This is done to prevent damage to the solenoid valves, which have
* been observed to become quite hot after extended use.
*
* Note, this class requires compatible hardware (e.g. valves with a
* block center position) to prevent actuator motion when solenoids
* are de-energized.
*
* @author James <james@team2168.org>
*
*/
public class MomentaryDoubleSolenoid extends DoubleSolenoid{
  private Timer latchTimer;
  private long latchTime; //time to hold the output energized
  private boolean energized = false; //flag to keep track of an active delay
  
  /**
  * A double solenoid which leaves its output energized for the specified
  * delay time period (ms).
  *
  * @param forwardChannel The forward channel on the module to control.
  * @param reverseChannel The reverse channel on the module to control.
  * @param delay The time in ms to leave the solenoid outputs energized.
  */
  public MomentaryDoubleSolenoid(final int forwardChannel,
      final int reverseChannel, long delay) {
    super(forwardChannel, reverseChannel);
    latchTime = delay;
  }
  
  /**
  * A double solenoid which leaves its output energized for the default
  * time period (1s).
  *
  * @param forwardChannel The forward channel on the module to control.
  * @param reverseChannel The reverse channel on the module to control.
  */
  public MomentaryDoubleSolenoid(final int forwardChannel,
      final int reverseChannel) {
    this(forwardChannel, reverseChannel, (long) 1000);
  }
  
  /**
  * A double solenoid which leaves its output energized for the specified
  * delay time period (ms).
  *
  * @param moduleNumber The module position the relay module is installed in
  * on the CRIO.
  * @param forwardChannel The forward channel on the module to control.
  * @param reverseChannel The reverse channel on the module to control.
  * @param delay The time in ms to leave the solenoid outputs energized.
  */
  public MomentaryDoubleSolenoid(final int moduleNumber,
      final int forwardChannel, final int reverseChannel, long delay) {
    super(moduleNumber, forwardChannel, reverseChannel);
    latchTime = delay;
  }
  
  /**
  * A double solenoid which leaves its output energized for the default
  * time period (1s).
  *
  * @param moduleNumber The module position the relay module is installed in
  * on the CRIO.
  * @param forwardChannel The forward channel on the module to control.
  * @param reverseChannel The reverse channel on the module to control.
  */
  public MomentaryDoubleSolenoid(final int moduleNumber,
      final int forwardChannel, final int reverseChannel) {
    this(moduleNumber, forwardChannel, reverseChannel, (long) 1000);
  }
  
  /**
   *
   */
  public void set(final DoubleSolenoid.Value value) {
    //If there is currently an active timerTask, kill it
    if(energized) latchTimer.cancel();
    
    energized = true;
    //Don't schedule a callback if the solenoid is explicitly set to off.
    if(value != Value.kOff) {
      latchTimer = new Timer();
      latchTimer.schedule(new LatchTimerTask(), latchTime);
    }
    super.set(value);
  }
  
  /**
  * This method will be called after the specified amount of time to leave
  * the solenoid energized has elapsed. If changes the output state of the
  * solenoid, and cleans up the associated TimerTask.
  */
  private void turnOff() {
    super.set(Value.kOff);
    latchTimer.cancel();
    energized = false;
  }
  
  /**
  * This task's run() method will be executed at the scheduled time specified
  * in the constructor, at which point the solenoid output will be
  * de-energized.
  *
  * @author James
  *
  */
  private class LatchTimerTask extends TimerTask {
    public void run() {
      turnOff();
    }
  }
}