DoubleJTextfieldWithLabel.java

package com.javamarcher.window;

import java.util.Locale;

import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;

import com.javamarcher.util.ActionGeneric;

public class DoubleJTextfieldWithLabel extends LabelBasedUIComponent {
	private final ActionGeneric<Double> updateAction;
	
	public DoubleJTextfieldWithLabel(String label, double startValue, ActionGeneric<Double> updateAction, int commaDigitCount, int columnWidth) {
		super(label);
		this.updateAction = updateAction;
		
		final JTextField textField = new JTextField(String.format(Locale.US, "%." + commaDigitCount + "f", startValue), columnWidth);
		textField.getDocument().addDocumentListener(new DocumentListener() {
			@Override
			public void removeUpdate(DocumentEvent e) {
				updateValue(e.getDocument());
			}
			
			@Override
			public void insertUpdate(DocumentEvent e) {
				updateValue(e.getDocument());
			}
			
			@Override
			public void changedUpdate(DocumentEvent e) {
				// Nothing to do here.
			}
		});
		
		addComponentToContainer(textField);
	}
	
	/**
	 * Updates the textfield String data if possible.
	 * Should be called if the textfield is altered. 
	 */
	private void updateValue(Document document) {
		String textfieldString = null;
		try {
			textfieldString = document.getText(0, document.getEndPosition().getOffset());
		} catch (BadLocationException e) {
			System.err.println(e.toString());
		}
		
		// Update value only if string is a valid double
		if(textfieldString != null) {
			try {
				final double parsedTextData = Double.parseDouble(textfieldString);
				// Trigger update action
				updateAction.performAction(parsedTextData);
			} catch(NumberFormatException e) {
				// Nothing to do here
			}
		}
	}
}