cannot find symbol, keyEvent constants java

I've created a Map containing a KeyEvent constant as key and a JButton as data and I add them to the Map inside a createButton function:

 /*TouchType.java*/
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JTextArea;
import javax.swing.JButton;
import javax.swing.JLabel;
import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;
import javax.swing.JScrollPane;
//for the map
import java.util.Map;
import java.util.HashMap;
import java.util.Set;
import java.util.TreeSet;   
public class TouchType extends JFrame{
    public TouchType(){//constructor
        super("Typing application");
        ...     
        Map<Integer,Object> mp = new HashMap<Integer,Object>();//declaring a map object
        ...
        row1.add(createButton(VK_DEAD_TILDE, "~"));     
        row1.add(createButton(VK_1, "1"));      
        row1.add(createButton(VK_2, "2"));
        ...
}//end of constructor

private void createButton(int keyCode, String name){
    newButton = new JButton(name);
    mp.put(keyCode, newButton);
}

Unfortunately the compiler complains about the constants, here is a sample error:

G:\JAVA\GUI\2015\createFrames\keyboard>javac *.java
TouchType.java:54: error: cannot find symbol
                row1.add(createButton(VK_DEAD_TILDE, "~"));
                                      ^
  symbol:   variable VK_DEAD_TILDE
  location: class TouchType
TouchType.java:55: error: cannot find symbol
                row1.add(createButton(VK_1, "1"));
                                      ^
  symbol:   variable VK_1
  location: class TouchType
TouchType.java:56: error: cannot find symbol
                row1.add(createButton(VK_2, "2"));
                                      ^
  symbol:   variable VK_2
  location: class TouchType
TouchType.java:57: error: cannot find symbol
                row1.add(createButton(VK_3, "3"));
                                      ^
  symbol:   variable VK_3
  location: class TouchType
TouchType.java:58: error: cannot find symbol
                row1.add(createButton(VK_4, "4"));
                                      ^
  symbol:   variable VK_4
  location: class TouchType
TouchType.java:59: error: cannot find symbol
                row1.add(createButton(VK_5, "5"));
                                      ^
  symbol:   variable VK_5
  location: class TouchType
TouchType.java:60: error: cannot find symbol
                row1.add(createButton(VK_6, "6"));
                                      ^
  symbol:   variable VK_6
  location: class TouchType
TouchType.java:61: error: cannot find symbol
                row1.add(createButton(VK_7, "7"));
                                      ^
  symbol:   variable VK_7
  location: class TouchType
TouchType.java:62: error: cannot find symbol
                row1.add(createButton(VK_8, "8"));
                                      ^
  symbol:   variable VK_8
  location: class TouchType
TouchType.java:63: error: cannot find symbol
                row1.add(createButton(VK_9, "9"));

Any idea why please? Can't quite understand...sorry, new to Java!