Keypad

package application;

import com.pi4j.io.gpio.GpioController;
import com.pi4j.io.gpio.GpioFactory;
import com.pi4j.io.gpio.GpioPinDigitalInput;
import com.pi4j.io.gpio.GpioPinDigitalOutput;
import com.pi4j.io.gpio.Pin;
import com.pi4j.io.gpio.PinPullResistance;
import com.pi4j.io.gpio.PinState;
import com.pi4j.io.gpio.RaspiPin;
import com.pi4j.io.gpio.event.GpioPinDigitalStateChangeEvent;
import com.pi4j.io.gpio.event.GpioPinListenerDigital;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.ArrayList;
import java.util.List;

public class KeypadTest {

   private List<PropertyChangeListener> listener = new ArrayList<PropertyChangeListener>();
   public static final String KEY = "key";
   private char keyPressed;

   /** The Constant KEYPAD. */
   private static final char layout[][] = {
            { '1', '2', '3' },
            { '4', '5', '6' },
            { '7', '8', '9' },
            { 'A', '0', 'B' }
            };

   /** The gpio. */
   private final GpioController gpio = GpioFactory.getInstance();

   /** The Constant PIN_1_IN. */
   private static final Pin PIN_1_IN = RaspiPin.GPIO_24;

   /** The Constant PIN_2_IN. */
   private static final Pin PIN_2_IN = RaspiPin.GPIO_25;

   /** The Constant PIN_3_IN. */
   private static final Pin PIN_3_IN = RaspiPin.GPIO_26;

   /** The Constant PIN_4_IN. */
   private static final Pin PIN_4_IN = RaspiPin.GPIO_23;

   /** The Constant PIN_5_OUT. */
   private static final Pin PIN_5_OUT = RaspiPin.GPIO_27;

   /** The Constant PIN_6_OUT. */
   private static final Pin PIN_6_OUT = RaspiPin.GPIO_28;

   /** The Constant PIN_7_OUT. */
   private static final Pin PIN_7_OUT = RaspiPin.GPIO_29;


   /** The Row 1. */
   private final GpioPinDigitalInput row1 = gpio
         .provisionDigitalInputPin(PIN_1_IN, PinPullResistance.PULL_UP);

   /** The Row 2. */
   private final GpioPinDigitalInput row2 = gpio
         .provisionDigitalInputPin(PIN_2_IN, PinPullResistance.PULL_UP);

   /** The Row 3. */
   private final GpioPinDigitalInput row3 = gpio
         .provisionDigitalInputPin(PIN_3_IN, PinPullResistance.PULL_UP);

   /** The Row 4. */
   private final GpioPinDigitalInput row4 = gpio
         .provisionDigitalInputPin(PIN_4_IN, PinPullResistance.PULL_UP);

   /** The Column 5. */
   private final GpioPinDigitalOutput col5 = gpio
         .provisionDigitalOutputPin(PIN_5_OUT);

   /** The Column 6. */
   private final GpioPinDigitalOutput col6 = gpio
         .provisionDigitalOutputPin(PIN_6_OUT);

   /** The Column 7. */
   private final GpioPinDigitalOutput col7 = gpio
         .provisionDigitalOutputPin(PIN_7_OUT);


   /** The Columns. */
   private final GpioPinDigitalOutput theColumns[] = { col5, col6,
         col7 };

   /** The input. */
   private GpioPinDigitalInput theInput;

   /** The in id. */
   private int theLin;

   /** The in id. */
   private int theCol;

   /**
    * Instantiates a new piezo keypad.
    */
   public KeypadTest() {
      initListeners();
   }

   /**
    * Find output.
    *
    * Sets output lines to high and then to low one by one. Then the input line
    * is tested. If its state is low, we have the right output line and
    * therefore a mapping to a key on the keypad.
    */
   private void findOutput() {
      // now test the inputs by setting the outputs from high to low
      // one by one
      for (int myO = 0; myO < theColumns.length; myO++) {
         for (final GpioPinDigitalOutput myTheOutput : theColumns) {
            myTheOutput.high();
         }

         theColumns[myO].low();

         // input found?
         if (theInput.isLow()) {
            theCol = myO;
            checkPins();
            try {
               Thread.sleep(200);
            } catch (InterruptedException e) {
            }
            break;
         }
      }

      for (final GpioPinDigitalOutput myTheOutput : theColumns) {
         myTheOutput.low();
      }
   }

   /**
    * Check pins.
    *
    * Determins the pressed key based on the activated GPIO pins.
    */
   private synchronized void checkPins() {

      notifyListeners(this, KEY, this.keyPressed,
            this.keyPressed = layout[theLin - 1][theCol]);

       System.out.println(layout[theLin - 1][theCol]);
   }

   /**
    * Inits the listeners.
    */
   private void initListeners() {
      row1.addListener(new GpioPinListenerDigital() {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent event) {
            if (event.getState() == PinState.LOW) {
               theInput = row1;
               theLin = 1;
               findOutput();
            }
         }
      });
      row2.addListener(new GpioPinListenerDigital() {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent event) {
            if (event.getState() == PinState.LOW) {
               theInput = row2;
               theLin = 2;
               findOutput();
            }
         }
      });
      row3.addListener(new GpioPinListenerDigital() {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent event) {
            if (event.getState() == PinState.LOW) {
               theInput = row3;
               theLin = 3;
               findOutput();
            }
         }
      });
      row4.addListener(new GpioPinListenerDigital() {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent event) {
            if (event.getState() == PinState.LOW) {
               theInput = row4;
               theLin = 4;
               findOutput();
            }
         }
      });
   }

   private void notifyListeners(Object object, String property, char oldValue,
         char newValue) {
      for (PropertyChangeListener name : listener) {
         name.propertyChange(new PropertyChangeEvent(this, property,
               oldValue, newValue));
      }
   }

   public void addChangeListener(PropertyChangeListener newListener) {
      listener.add(newListener);
   }
}