/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.dialogs;

/**
 * The IInputValidator is the interface for simple validators. 
 * @see org.eclipse.jface.dialogs.InputDialog
 */
public interface IInputValidator {
    /**
     * Validates the given string.  Returns an error message to display
     * if the new text is invalid.  Returns <code>null</code> if there
     * is no error.  Note that the empty string is not treated the same
     * as <code>null</code>; it indicates an error state but with no message
     * to display.
     * 
     * @param newText the text to check for validity
     * 
     * @return an error message or <code>null</code> if no error
     */
    public String isValid(String newText);
}