[Ben Wolsieffer]

Are you using the Command framework, or just SampleRobot?

If you are using commands, I would create a Command with a 100 ms timeout, which would open the solenoid in the initialize() method, and close it in the end() method.

If you are just using a simple teleop loop, then it is a little more complicated. Here is some psuedo code that should give you an idea of how to do it:

// Class variables (their values must persist between iterations of the loop)
boolean solenoidOpen = false;
long solenoidOpenTime;

// Runs on each iteration of the teleop loop
if (!solenoidOpen) {
    if(solenoidShouldBeTriggered) {
        openSolenoid();
        solenoidOpened = true;
        solenoidOpenTime = System.currentTimeMillis();
    }
} else {
    if (System.currentTimeMillis() - solenoidOpenTime > 100) {
         closeSolenoid();
         solenoidOpen = false;
    }
}

If you want more clarification, just ask.