Beginner #javafx #nashorn calculator

calc.js

/**
 * This Nashorn script is port of "Hello Math" JavaFX example
 * at http://www.javafxtutorials.com/javafxsimplecode/
 *
 * Ported by: https://twitter.com/sundararajan_a
 *
 * "mindless" port with these changes:
 *
 *    Java imports -> Java.type
 *    Bean style getter/setter -> property access style
 *    Java closures -> script functions
 */

// JavaFX classes referred here
var Button = Java.type("javafx.scene.control.Button");
var GridPane = Java.type("javafx.scene.layout.GridPane");
var Label = Java.type("javafx.scene.control.Label");
var Pos = Java.type("javafx.geometry.Pos");
var Scene = Java.type("javafx.scene.Scene");
var TextField = Java.type("javafx.scene.control.TextField");

// variables to hold JavaFX UI control objects
var txtnum1, txtnum2;
var btnadd, btnsub, btndiv, btnmul, btnclear;
var lblanswer;

function start(primaryStage) {
    //make the controls
    txtnum1 = new TextField();
    txtnum2 = new TextField();
    btnadd = new Button("+");
    btnsub = new Button("-");
    btnmul = new Button("x");
    btndiv = new Button("/");
    btnclear = new Button("Clear");
    lblanswer = new Label("?");

    //center text in label
    lblanswer.alignment = Pos.CENTER;

    //apply ccs-like style to label (yes, you can)
    lblanswer.style = "-fx-border-color: #000; -fx-padding: 5px;";

    //make container for app
    var root = new GridPane();

    //put container in middle of scene
    root.alignment = Pos.CENTER;

    //setspacing between controls in grid
    root.hgap = 10;
    root.vgap = 10;

    //add to grid, cell by cell
    root.add(btnadd,0,0);
    root.add(btnsub,1,0);
    root.add(btnmul,0,1);
    root.add(btndiv,1,1);
    root.add(txtnum1, 0,2);
    root.add(txtnum2,1,2);

    //last 2 rows span across 2 columns
    //col, rol, colspan, rowspan
    root.add(lblanswer,0,3,2,1);
    root.add(btnclear,0,4,2,1);

    //set widths of all controls in separate method
    setWidths();

    //attach buttons to code in separate method
    attachCode();

    //usual stuff
    var scene = new Scene(root, 300, 250);
    primaryStage.title = "Mathtastic 1.0";
    primaryStage.scene = scene;
    primaryStage.show();
}

function setWidths(){
    //set widths of all controls
    txtnum1.prefWidth = 70;
    txtnum2.prefWidth = 70;
    btnadd.prefWidth = 70;
    btnsub.prefWidth = 70;
    btnmul.prefWidth = 70;
    btndiv.prefWidth = 70;
    btnclear.prefWidth = 150;
    lblanswer.prefWidth = 150;
}
   
function attachCode() {
    //have each button run BTNCODE when clicked
    btnadd.onAction = btncode;
    btnsub.onAction = btncode;
    btnmul.onAction = btncode;
    btndiv.onAction = btncode;
    btnclear.onAction = btncode;
}

function btncode(e) {
    var num1, num2, answer;
    var symbol;

    //e tells us which button was clicked
    if (e.source == btnclear) {
        txtnum1.text = "";
        txtnum2.text = "";
        lblanswer.text = "?";
        txtnum1.requestFocus();
        return;
    }

    //read numbers in from textfields
    num1 = parseInt(txtnum1.text);
    num2 = parseInt(txtnum2.text);

    if (e.source == btnadd) {
        symbol = '+';
        answer = num1 + num2;
    } else if (e.source == btnsub) {
        symbol = '-';
        answer = num1 - num2;
    } else if (e.source == btnmul) {
        symbol = 'x';
        answer = num1 * num2;
    } else {
        symbol = '/';
        answer = num1 / num2;
    }

    //display answer
    lblanswer.text = "" + num1 + symbol + num2 + "=" + answer;
}

To run that script, use

jjs -fx calc.js

See also jjs man page at http://docs.oracle.com/javase/8/docs/technotes/tools/unix/jjs.html