4x4 Keypad Java Pi4J

package application;
import java.util.HashMap;

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;


public class RPi_4x4_Matrix {

   /** The Constant PINMAPPING. */
   private static final HashMap<String, String> PINMAPPING = new HashMap<String, String>();

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

   /** The COLUMN pins */
   private static final Pin COLUMN_1 = RaspiPin.GPIO_04;
   private static final Pin COLUMN_2 = RaspiPin.GPIO_03;
   private static final Pin COLUMN_3 = RaspiPin.GPIO_02;
   private static final Pin COLUMN_4 = RaspiPin.GPIO_01;

   /** The Digital COLUMN 1. */
   private GpioPinDigitalOutput theCOLUMN_1 = gpio
           .provisionDigitalOutputPin(COLUMN_1);

   /** The Digital COLUMN 2. */
   private GpioPinDigitalOutput theCOLUMN_2 = gpio
           .provisionDigitalOutputPin(COLUMN_2);

   /** The Digital COLUMN 3. */
   private GpioPinDigitalOutput theCOLUMN_3 = gpio
           .provisionDigitalOutputPin(COLUMN_3);

   /** The Digital COLUMN 4. */
   private GpioPinDigitalOutput theCOLUMN_4 = gpio
           .provisionDigitalOutputPin(COLUMN_4);

   /** The Digital Column Array **/
   private final GpioPinDigitalOutput theColumns[] = {
           theCOLUMN_1,
           theCOLUMN_2,
           theCOLUMN_3,
           theCOLUMN_4
   };

   /** The ROW pins */
   private static final Pin ROW_1 = RaspiPin.GPIO_08;
   private static final Pin ROW_2 = RaspiPin.GPIO_07;
   private static final Pin ROW_3 = RaspiPin.GPIO_06;
   private static final Pin ROW_4 = RaspiPin.GPIO_05;

   /** The Digital ROW 1. */
   private GpioPinDigitalInput theROW_1 = gpio
           .provisionDigitalInputPin(ROW_1, PinPullResistance.PULL_UP);

   /** The Digital ROW 2. */
   private GpioPinDigitalInput theROW_2 = gpio
            .provisionDigitalInputPin(ROW_2, PinPullResistance.PULL_UP);

   /** The Digital ROW 3. */
   private GpioPinDigitalInput theROW_3 = gpio
            .provisionDigitalInputPin(ROW_3, PinPullResistance.PULL_UP);

   /** The Digital ROW 4. */
   private GpioPinDigitalInput theROW_4 = gpio
            .provisionDigitalInputPin(ROW_4, PinPullResistance.PULL_UP);


   /** The RowInput */
   private GpioPinDigitalInput theRowInput;

   /** The row id */
   private int theInId;

   /** The row value */
   private int rowVal;

   /** The column value */
   private int colVal;


   /**
    * Find Column
    */
    private void findColumn() {
        for (int myO = 0; myO < theColumns.length; myO++) {
            for (final GpioPinDigitalOutput myTheCol : theColumns)
            {
                myTheCol.high();
            }

            theColumns[myO].low();

             // column found?
             if (theRowInput.isHigh()) {

                 rowVal = theInId;

                 if (myO == 0)
                 {
                    colVal = 1;
                 }
                 else if(myO == 1)
                 {
                    colVal = 2;
                 }
                 else if(myO == 2)
                 {
                     colVal = 3;
                 }
                 else if(myO == 3)
                 {
                     colVal = 4;
                 }
                 checkPins();
                 break;
             }
        }
        for (final GpioPinDigitalOutput myTheCol : theColumns)
        {
            myTheCol.low();
        }

    } // end findColumn().


    /**
        * Check pins.
        *
        * Determins the pressed key based on the activated GPIO pins.
        */
       private synchronized void checkPins()
       {
          if (rowVal > 1 || rowVal < 4 && colVal > 1 || colVal < 4)
          {
             System.out.println("RowID:" + rowVal + " ColumnID:" + colVal);

             String key = Integer.toString(rowVal)
                         + Integer.toString(colVal);
             System.out.println("Key: " + PINMAPPING.get(key));

              colVal = 0;
              rowVal = 0;
          }
       }

   /**
    * Instantiates a new piezo keypad.
    */
   public RPi_4x4_Matrix()
   {
      initMapping();
      initListeners();
   }

   /**
    * Inits the listeners.
    */
   private void initListeners()
   {
      theROW_1.addListener(new GpioPinListenerDigital()
      {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent aEvent)
         {
            if (aEvent.getState() == PinState.LOW)
            {
                System.out.println("The Row 1 is LOW");
            } else {
                System.out.println("The Row 1 is HIGH");
                theRowInput = theROW_1;
                theInId = 1;
                findColumn();
            }
         }
      });
      theROW_2.addListener(new GpioPinListenerDigital()
      {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent aEvent)
         {
            if (aEvent.getState() == PinState.LOW)
            {
                System.out.println("The Row 2 is LOW");
            } else {
                System.out.println("The Row 2 is HIGH");
                theRowInput = theROW_2;
                theInId = 2;
                findColumn();
            }
         }
      });
      theROW_3.addListener(new GpioPinListenerDigital()
      {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent aEvent)
         {
            if (aEvent.getState() == PinState.LOW)
            {
                System.out.println("The Row 3 is LOW");
            } else {
                System.out.println("The Row 3 is HIGH");
                theRowInput = theROW_3;
                theInId = 3;
                findColumn();
            }
         }
      });
      theROW_4.addListener(new GpioPinListenerDigital()
      {
         @Override
         public void handleGpioPinDigitalStateChangeEvent(
               final GpioPinDigitalStateChangeEvent aEvent)
         {
            if (aEvent.getState() == PinState.LOW)
            {
                System.out.println("The Row 4 is LOW");
            } else {
                System.out.println("The Row 4 is HIGH");
                theRowInput = theROW_4;
                theInId = 4;
                findColumn();
            }
         }
      });
   }



    /**
        * Inits the mapping.
        *
        * Maps input/output line to key on keypad.
        */
       private void initMapping()
       {
          PINMAPPING.put("11", "1");
          PINMAPPING.put("12", "2");
          PINMAPPING.put("13", "3");
          PINMAPPING.put("14", "A");
          PINMAPPING.put("21", "4");
          PINMAPPING.put("22", "5");
          PINMAPPING.put("23", "6");
          PINMAPPING.put("24", "B");
          PINMAPPING.put("31", "7");
          PINMAPPING.put("32", "8");
          PINMAPPING.put("33", "9");
          PINMAPPING.put("34", "C");
          PINMAPPING.put("41", "*");
          PINMAPPING.put("42", "0");
          PINMAPPING.put("43", "#");
          PINMAPPING.put("44", "D");
       }
}