Cancellable password dialog

Made it possible to cancel the password dialog.

src/eu/tankernn/accounts/AccountManager.java

@@ -8,6 +8,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
+import java.util.concurrent.CancellationException;
 
 import javax.swing.JOptionPane;
 
@@ -82,14 +83,13 @@ public class AccountManager {
 				try {
 					char[] password = PasswordDialog
 							.showPasswordDialog("The data is encrypted, please enter the password to decrypt it.");
-					if (password == null) {
-						// Start the program without loading a file
-						return;
-					}
 					jsonString = data instanceof String ? Encryption.decryptEncoded((String) data, password)
 							: Encryption.decrypt(new EncryptedComplex((byte[][]) data), password);
 					lastPassword = password;
 					break;
+				} catch (CancellationException ex) {
+					// Start the program without loading a file
+					return;
 				} catch (InvalidPasswordException e) {
 					continue;
 				}
@@ -133,8 +133,13 @@ public class AccountManager {
 			String encryptedData = new String(newData);
 			if (saveWithEncryption) {
 				while (lastPassword == null || lastPassword.length < 5) {
-					lastPassword = PasswordDialog.showPasswordDialog(
-							"Select a password to encrypt the account file with. (At least 5 characters, preferrably longer)");
+					try {
+						lastPassword = PasswordDialog.showPasswordDialog(
+								"Select a password to encrypt the account file with. (At least 5 characters, preferrably longer)");
+					} catch (CancellationException ex) {
+						return;
+					}
+
 				}
 				encryptedData = Encryption.encryptEncoded(newData, lastPassword);
 			}
@@ -185,10 +190,6 @@ public class AccountManager {
 	 *         current list of accounts.
 	 */
 	public static String exportJSON() {
-//		JSONArray jsonArr = new JSONArray();
-//		for (Account a : accounts)
-//			jsonArr.put(new JSONObject(a));
-//		return jsonArr.toString();
 		return GSON.toJson(accounts);
 	}
 

src/eu/tankernn/accounts/frame/PasswordDialog.java

@@ -1,5 +1,7 @@
 package eu.tankernn.accounts.frame;
 
+import java.util.concurrent.CancellationException;
+
 import javax.swing.JComponent;
 import javax.swing.JLabel;
 import javax.swing.JOptionPane;
@@ -20,12 +22,18 @@ public class PasswordDialog {
 		result = JOptionPane.showConfirmDialog(null, new JComponent[] {label, password}, "Enter password", JOptionPane.OK_CANCEL_OPTION);
 	}
 	
-	public static char[] showPasswordDialog(String message) {
+	/**
+	 * Show a password input dialog.
+	 * @param message The message to display to the user when prompting for password.
+	 * @return The password entered
+	 * @throws CancellationException If the user clicks 'cancel'.
+	 */
+	public static char[] showPasswordDialog(String message) throws CancellationException {
 		PasswordDialog dialog = new PasswordDialog(message);
 		if (dialog.result == JOptionPane.OK_OPTION)
 			return dialog.password.getPassword();
 		else
-			return null;
+			throw new CancellationException();
 	}
 
 }