public void actionPerformed(ActionEvent e){
			// reset counts
			for (int i = 0; i < 26; i++){
				counts[i]=0;
			}
			
			try {
				// create file input stream
				Scanner input = new Scanner(new File(jtf.getText().trim()));
				
				while (input.hasNext()){
					String line = input.nextLine();
					
					for (int i = 0; i < line.length(); i++){
						if (Character.isLetter(line.charAt(i))){
							counts[Character.toUpperCase(line.charAt(i)) - 'A']++;
						}
					}
				}
				
				display.showHistogram(counts);
			} catch (FileNotFoundException ex){
				System.out.println("File not found: " + jtf.getText().trim());
			}
		}