How to give keycodes from a properties file in javafx - javafx

Question

Currently i have configured JavaFX keyEvents for key board controllers for each task. What i want is to configure there keys from a properties file rather than hard coding in the code.
The implementation :
final KeyCombination keyCombinationShiftC = new KeyCodeCombination(
KeyCode.ENTER, KeyCombination.CONTROL_DOWN);
javafx.event.EventHandler<javafx.scene.input.KeyEvent> handler = event -> {
if (keyCombinationShiftC.match(event)) {
try {
if (finalSubTotalPrice > 0) {
paymentAction();
} else {
Alert alert = new Alert(Alert.AlertType.WARNING);
alert.setTitle(app.values.getProperty("WARNING_TITLE"));
alert.setHeaderText(app.values.getProperty("INVALID_NO_OF_ITEMS"));
alert.setContentText(app.values.getProperty("INVALID_NO_OF_ITEMS_DIALOG"));
alert.showAndWait();
}
} catch (Exception e1) {
e1.printStackTrace();
}
}
switch (event.getCode()) {
case F10:
try {
removeAction();
} catch (Exception e1) {
e1.printStackTrace();
}
break;
case F1:
try {
searchField.requestFocus();
} catch (Exception e1) {
e1.printStackTrace();
}
break;
case F5:
try {
customVatDiscountCalculation();
} catch (Exception e1) {
e1.printStackTrace();
}
break;
}
The ENTER+CNTRL_DOWN, F5, F10, F1 keys need to be assign for other keys without changing the code using a properties file.
If i try to get the Strings from the properties file, i fail to do that. as below. It says a constant expression is required for the case.
public static final KeyCode REMOVE_KEY = KeyCode.getKeyCode(app.values.getProperty("REMOVE_KEY"));
switch (event.getCode()) {
case REMOVE_KEY:
try {
removeAction();
} catch (Exception e1) {
e1.printStackTrace();
}
break;
}