Java SE (Java Platform, Standard Edition)

Hello,

I'm trying to get a JTable to behave when the arrow keys are pressed as if ctrl was being held down. In other words, when the user presses the up or down arrow, I want only the lead (the highlighted cell) to change, not the selection.

My thought was that I could use key bindings and Actions to set the arrow key actions equal to the arrow key plus ctrl Action. In a way, I'm trying to "trick" the JTable into thinking that ctrl is being held down when the arrow keys are pressed.

However, I'm pretty new to key bindings, and I'm getting a null pointer exception when I try to set the ctrl Action to occur when the arrow key (without ctrl) event is triggered. I've been through every tutorial I could find, and I'm still not sure what I'm doing wrong. Could anybody point me in the right direction?

Here's a piece of code using only the up arrow that demonstrates the problem:

import javax.swing.*;
import java.awt.event.*;


public class TestTableSelection{

	JTable table;

	public TestTableSelection(){
		JFrame frame = new JFrame("Test Table Selection");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		//give the table random data
		String [][] data = new String [10][5];
		String [] names = new String [5];
		for(int i = 0; i < 5; i++){
			names[i] = "C: " + i;
			for(int j = 0; j < 10; j++){
				data[j] = "t: " + (int)(Math.random()*100);

			}

		}



		table = new JTable(data, names);



		//the arrows without ctrl is the key I want to reroute

		Object key = table.getInputMap(JComponent.WHEN_FOCUSED).get(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0));

//the arrows with ctrl is the key of the action I want to reroute TO

		Object ctrlKey = table.getInputMap(JComponent.WHEN_FOCUSED).get(KeyStroke.getKeyStroke(KeyEvent.VK_UP, java.awt.event.InputEvent.CTRL_DOWN_MASK));

//the action that occurrs when ctrl plus up is pressed

		Action ctrlAction = table.getActionMap().get(ctrlKey);

		//this should set the arrow without ctrl Action equal to the arrow with ctrl.. right?

		table.getActionMap().put(key, ctrlAction);

	

		frame.getContentPane().add(new JScrollPane(table));

		frame.setSize(250, 250);

		frame.setVisible(true);

	}



	public static void main(String[] args){

		new TestTableSelection();

	}			

}
Some print statements revealed that key, ctrlKey, and ctrlAction are all null, resulting in a NPE when I try to put key and ctrlAction into the table's ActionMap.

Does anybody see something I'm doing wrong? Is there a better way to accomplish my goal of changing the JTable behavior when an arrow is pressed?