Java Dialogs

dialogs.java

/**
 * Dialogs
 * Some handy functions to get various types of data from a user using JoptionPane
 * @author Karl Hobley
 * @version r23
 */

import javax.swing.*;
import javax.swing.filechooser.*;
import java.io.File;

public class Dialogs {
    /**
     * Displays an input dialog to the user
     * @param message Message to be displayed to the user
     * @param defaultValue Value to initialise the input box to
     * @return String that the user typed in. Null if they cancelled
     */
    public static String input(final String message, final Object defaultValue) {
        // Display the input dialog
        return JOptionPane.showInputDialog(null, message, defaultValue);
    }
    
    /**
     * Displays an information message to the user
     * @param message Message to be displayed to the user
     */
    public static void info(final String message) {
        // Display the info message
        JOptionPane.showMessageDialog(null, message, "Information", JOptionPane.INFORMATION_MESSAGE);
    }
    
    /**
     * Displays an error message to the user
     * @param message Message to be displayed to the user
     */
    public static void error(final String message) {
        // Display the error message
        JOptionPane.showMessageDialog(null, message, "Error", JOptionPane.ERROR_MESSAGE);
    }
    
    /**
     * Displays a yes/no dialog to the user
     * @param message Message for input prompt
     * @param cancelOption Set to true to put a cancel option on the box
     * @return True if yes pressed, False if no pressed, null if cancel pressed
     */
    public static Boolean yesNo(final String message, final boolean cancelOption) {
        // Find options
        final int options = cancelOption ? JOptionPane.YES_NO_CANCEL_OPTION : JOptionPane.YES_NO_OPTION;
        
        // Show user the dialog
        final int answer = JOptionPane.showConfirmDialog(null, message, "Input", options);
        
        // Check answer
        switch (answer) {
            case JOptionPane.YES_OPTION:
                return true;
            case JOptionPane.NO_OPTION:
                return false;
            case JOptionPane.CANCEL_OPTION:
                return null;
        }
        
        // This will never execute
        // It is just to make the compiler happy :)
        return null;
    }
    
    /**
     * Displays a file open/save dialog to the user
     * Only allows one type of extension
     * @param extensionDescription Description of the extension thats being looked for
     * @param extesions List of extensions to look for
     * @param openFile Set to true to open file set to false to save file
     * @return Filename of the selected file
     */
    public static String fileDialog(final String extensionDescription, final String extension, final boolean openFile) {
        // Create JFileChooser
        final JFileChooser chooser = new JFileChooser();
        
        // Add filename extensions
        final FileNameExtensionFilter filter = new FileNameExtensionFilter(extensionDescription + " (*." + extension + ")", extension);
        chooser.setFileFilter(filter);
        
        // Loop forever
        String fileName = null;
        for (;;) {
            // Show dialog
            final int result = openFile ? chooser.showOpenDialog(null) : chooser.showSaveDialog(null);
            
            // Check result
            if (result != JFileChooser.APPROVE_OPTION) {
                return null;
            }
            
            // Get filename
            fileName = chooser.getSelectedFile().getAbsolutePath();
            
            // Check if the file exists
            final File f = new File(fileName);
            if (f.exists()) {
                // Check if the user is trying to save a file
                if (!openFile) {
                    // User attempting to save to a file that exists
                    final String shortFileName = chooser.getSelectedFile().getName();
                    final Boolean replaceFile = getBoolean(shortFileName + " already exists. Would you like to replace it?", false);
                    
                    // Check if the user wants to replace the file
                    if (replaceFile) {
                        break;
                    }
                } else {
                    break;
                }
            } else {
                // Check if the user is trying to open a file
                if (openFile) {
                    // User trying to open a file that doesnt exist
                    error("File doesn't exist. Please try again.");
                } else {
                    break;
                }
            }
        }
        // Return
        return fileName;
    }
    
    /**
     * Displays a list of options to the user and returns the one the user chooses
     * @param message Message to be displayed to the user
     * @param options The list of options
     * @param defaultValue Value that is already set
     */
    public static String getOption(final String message, final String[] options, final String defaultValue) {
        return (String) JOptionPane.showInputDialog(null, message, "Choose one", JOptionPane.QUESTION_MESSAGE, null, options, defaultValue);
    }
    
    /**
     * Gets an integer from the user
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @return Integer inputted by user
     */
    public static Integer getInteger(final String message, final Integer defaultValue) {
        // Call main getInteger function with min and max nulled out
        return getInteger(message, defaultValue, null, null);
    }
    
    /**
     * Gets an integer from the user
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @param minVal Minimum value allowed to input
     * @param maxVal Maximum value allowed to input
     * @return Integer inputted by user
     */
    public static Integer getInteger(final String message, final Integer defaultValue, final Integer min, final Integer max) {
        // Loop until return
        for (;;) {
            // Get input string
            final String textInput = input(message, defaultValue);
            
            // Check if the user pressed cancel
            if (textInput == null) {
                return null;
            }
            
            // Attempt to convert to Integer
            Integer input;
            try {
                input = Integer.parseInt(textInput);
            } catch (NumberFormatException ex) {
                // Display error
                if (textInput.equals("")) {
                    error("Please type a whole number in the box.");
                } else {
                    error("Couldn't recognise \"" + textInput + "\". Make sure that you typed a whole number.");
                }
                
                // Run loop again
                continue;
            }
            
            // Check min
            if (min != null && input < min) {
                // Display error
                error("Number to low! The number must be at least " + min + ".");
                
                // Run loop again
                continue;
            }
            
            // Check max
            if (max != null && input > max) {
                // Display error
                error("Number to high! The number must not be higher than " + max + ".");
                
                // Run loop again
                continue;
            }
            
            // Found integer. Return it
            return input;
        }
    }
    
    /**
     * Gets a float from the user
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @return Float inputted by user
     */
    public static Float getFloat(final String message, final Float defaultValue) {
        // Call main getFloat function with min and max nulled out
        return getFloat(message, defaultValue, null, null);
    }
    
    /**
     * Gets a float from the user
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @param minVal Minimum value allowed to input
     * @param maxVal Maximum value allowed to input
     * @return Float inputted by user
     */
    public static Float getFloat(final String message, final Float defaultValue, final Float min, final Float max) {
        // Loop until return
        for (;;) {
            // Get input string
            final String textInput = input(message, defaultValue);
            
            // Check if the user pressed cancel
            if (textInput == null) {
                return null;
            }
            
            // Attempt to convert to Float
            Float input;
            try {
                input = Float.parseFloat(textInput);
            } catch (NumberFormatException ex) {
                // Display error
                if (textInput.equals("")) {
                    error("Please type a number in the box.");
                } else {
                    error("Couldn't recognise \"" + textInput + "\". Make sure that you typed a number.");
                }
                
                // Run loop again
                continue;
            }
            
            // Check min
            if (min != null && input < min) {
                // Display error
                error("Number to low! The number must be at least " + min + ".");
                
                // Run loop again
                continue;
            }
            
            // Check max
            if (max != null && input > max) {
                // Display error
                error("Number to high! The number must not be higher than " + max + ".");
                
                // Run loop again
                continue;
            }
            
            // Found float. Return it
            return input;
        }
    }
    
    /**
     * Gets a string from the user
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @return String inputted by user
     */
    public static String getString(final String message, final String defaultValue) {
        // Get string
        return getString(message, defaultValue, false);
    }
    
    /**
     * Gets a string from the user
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @param required Set to true if the string is requried
     * @return String inputted by user
     */
    public static String getString(final String message, final String defaultValue, final boolean required) {
        // Loop until return
        for (;;) {
            // Get input string
            final String textInput = input(message, defaultValue);
            
            // Check if the user pressed cancel
            if (textInput == null) {
                return null;
            }
            
            // If an input is required, make sure the user entered something
            if (required && textInput.equals("")) {
                // Display error
                error("Please type something in the box.");
                
                // Run loop again
                continue;
            }
            
            // Return the string
            return textInput;
        }
    }
    
    /**
     * Gets a boolean from the user
     * @param message Message for input prompt
     * @return Boolean inputted by user
     */
    public static Boolean getBoolean(final String message) {
        // Get boolean
        return getBoolean(message, true);
    }
    
    /**
     * Gets a boolean from the user
     * @param message Message for input prompt
     * @param cancelOption Set to true to put a cancel option on the box
     * @return Boolean inputted by user
     */
    public static Boolean getBoolean(final String message, final boolean cancelOption) {
        // This is equivilant to the yes/no dialog
        return yesNo(message, cancelOption);
    }
    
    /**
     * Checks if an email address is valid
     * @param email The email address to check
     * @return True if valid, false if not
     */
    public static boolean isValidEmailAddress(final String email) {
        /*
         * I used this as a reference for finding what exactly a valid email address is:
         * https://en.wikipedia.org/wiki/Email_mailbox
         */
        
        // Split into 2 tokens (mailbox and domain)
        final String[] tokens = email.split("@");
        if (tokens.length != 2) {
            return false;
        }
        
        // Perform checks on both tokens
        for (final int token = 0; token < 2; token++) {
            // Get token length (needed in both checks, so its more efficient to calculate it only once)
            final int tokenLength = tokens[token].length();
            
            // Make sure beginning and last characters are not dots (these are valid in the middle though)
            if (tokens[token].charAt(0) == '.' || tokens[token].charAt(tokenLength - 1) == '.') {
                return false;
            }
            
            // Load valid characters
            final String validCharacters = (token == 0)
                    // Load mailbox valid characters
                    ? "abcdefghijklmnopqrstuvwxyz0123456789!#$%&'*+-/=?^_`{|}~."
                    // Load domain valid characters
                    : "abcdefghijklmnopqrstuvwxyz0123456789-.";
            
            // Check that all characters are valid
            tokens[token].toLowerCase();
            for (final int charNum = 0; charNum < tokenLength; charNum++) {
                // Check that this character is in valid characters
                if (validCharacters.indexOf(tokens[token].charAt(charNum)) == -1) {
                    return false; // Character is not in valid characters
                }
            }
        }
        
        // Passed all tests
        return true;
    }
    
    /**
     * Gets a string from the user and checks if it is a valid email address
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @return Email address inputted by user
     */
    public static String getEmailAddress(final String message, final String defaultValue) {
        // Get email address
        return getEmailAddress(message, defaultValue, false);
    }
    
    /**
     * Gets a string from the user and checks if it is a valid email address
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @param required Set to true if the string is required
     * @return Email address inputted by user
     */
    public static String getEmailAddress(final String message, final String defaultValue, final boolean required) {
        // Loop until return
        for (;;) {
            // Get input string
            final String textInput = getString(message, defaultValue, required);
            
            // Check if the user pressed cancel
            if (textInput == null) {
                return null;
            }
            
            // Bypass validation if blank was inputted but email not required
            if (textInput.equals("") && !required) {
                return "";
            }
            
            // Check that this string is a valid email address
            if (!isValidEmailAddress(textInput)) {
                // Display error
                error("Please enter a valid email address.");
                
                // Run loop again
                continue;
            }
            
            // Return the string
            return textInput;
        }
    }
    
    /**
     * Checks if a telephone number is valid
     * @param telephoneNumber The telephone number to check
     * @return True if valid, false if not
     */
    public static boolean isValidTelephoneNumber(final String telephoneNumber) {
        /*
         * This checks that the string contains only numbers and spaces
         */
        
        // Check characters
        final int stringLength = telephoneNumber.length();
        for (int charNum = 0; charNum < stringLength; charNum++) {
            // Check if the character is a digit or a space
            final char character = telephoneNumber.charAt(charNum);
            if (Character.isDigit(character)) {
                continue;
            } else if (character == ' ') {
                continue;
            }
            
            // Didn't match any of above, must be an invalid character
            return false;
        }
        
        // Passed all tests
        return true;
    }
    
    /**
     * Gets a string from the user and checks if it is a valid telephone number
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @return Telephone number inputted by user
     */
    public static String getTelephoneNumber(final String message, final String defaultValue) {
        // Get telephone number
        return getTelephoneNumber(message, defaultValue, false);
    }
    
    /**
     * Gets a string from the user and checks if it is a valid telephone number
     * @param message Message for input prompt
     * @param defaultValue Value to initialise the input box to
     * @param required Set to true if the string is required
     * @return Telephone number inputted by user
     */
    public static String getTelephoneNumber(final String message, final String defaultValue, final boolean required) {
        // Loop until return
        for (;;) {
            // Get input string
            final String textInput = getString(message, defaultValue, required);
            
            // Check if the user pressed cancel
            if (textInput == null) {
                return null;
            }
            
            // Bypass validation if blank was inputted but telephone number not required
            if (textInput.equals("") && !required) {
                return "";
            }
            
            // Check that this string is a valid telephone number
            if (!isValidTelephoneNumber(textInput)) {
                // Display error
                error("Please enter a valid telephone number.");
                
                // Run loop again
                continue;
            }
            
            // Return the string
            return textInput;
        }
    }
}