EVLib has its own interface for Digital sensors. It extends InputExtractor of type Boolean, which means that every DigitalSensor has to have a getValue method that returns a Boolean.

ftc/evlib/hardware/sensors/DigitalSensor.java

package ftc.evlib.hardware.sensors;

import ftc.electronvolts.util.InputExtractor;

/**
 * This file was made by the electronVolts, FTC team 7393
 * Date Created: 9/12/16
 * 
 * Interface for any type of digital sensor
 * examples: touch sensor, digital line sensor, magnetic reed switch
 *
 * @see InputExtractor
 * @see Sensors
 */
public interface DigitalSensor extends InputExtractor<Boolean> {
}

You can create a DigitalSensor from a DigitalChannel or TouchSensor using the Sensors factory class:

DigitalInput digitalInput = hardwareMap.touchSensor.get("limitSwitch");
DigitalSensor limitSwitch = Sensors.digitalSensor(digitalInput);

//To combine on one line:
DigitalSensor button = Sensors.digitalSensor(hardwareMap, "button");

To get the value of a DigitalSensor, call the getValue() method which returns a Boolean.

teletry.addData("limit switch pressed?", limitSwitch.getValue());

See also: Analog Sensors