From: Joonas Lehtinen <joonas.lehtinen@itmill.com>
Date: Thu, 2 Oct 2008 16:46:34 +0000 (+0000)
Subject: Rewrote the calculator example in clearer way. Now it could be used as the first... 
X-Git-Tag: 6.7.0.beta1~4033
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=8c0c39470d895eb90c345563ad814d17f3cff013;p=vaadin-framework.git

Rewrote the calculator example in clearer way. Now it could be used as the first example to introduce Toolkit programming model. (this is only suitable for 5.3.0 as it depends on Java 1.5)

svn changeset:5588/svn branch:trunk
---

diff --git a/src/com/itmill/toolkit/demo/Calc.java b/src/com/itmill/toolkit/demo/Calc.java
index 8d64945e72..4348826a67 100644
--- a/src/com/itmill/toolkit/demo/Calc.java
+++ b/src/com/itmill/toolkit/demo/Calc.java
@@ -9,134 +9,72 @@ import com.itmill.toolkit.ui.GridLayout;
 import com.itmill.toolkit.ui.Label;
 import com.itmill.toolkit.ui.Window;
 
-/**
- * <p>
- * An example application implementing a simple web-based calculator using IT
- * Mill Toolkit. The application opens up a window and places the needed UI
- * components (display label, buttons etc.) on it, and registers a button click
- * listener for them.
- * </p>
- * 
- * <p>
- * When any of the buttons are pressed the application finds out which button
- * was pressed, figures what that button does, and updates the user interface
- * accordingly.
- * </p>
- * 
- * @see com.itmill.toolkit.Application
- * @see com.itmill.toolkit.ui.Button.ClickListener
- */
-public class Calc extends com.itmill.toolkit.Application implements
-        Button.ClickListener {
-
-    /** The label used as the display */
-    private Label display = null;
-
-    /** Last completed result */
-    private double stored = 0.0;
+// Calculator is created by extending Application-class. Application is
+// deployed by adding ApplicationServlet to web.xml and this class as
+// "application" parameter to the servlet.
+public class Calc extends com.itmill.toolkit.Application {
 
-    /** The number being currently edited. */
+    // Calculation data model is automatically stored in the user session
     private double current = 0.0;
+    private double stored = 0.0;
+    private char lastOperationRequested = 'C';
 
-    /** Last activated operation. */
-    private String operation = "C";
-
-    /** Button captions. */
-    private static String[] captions = // Captions for the buttons
-    { "7", "8", "9", "/", "4", "5", "6", "*", "1", "2", "3", "-", "0", "=",
-            "C", "+" };
+    // User interface components
+    private final Label display = new Label("0.0");
+    private final GridLayout layout = new GridLayout(4, 5);
 
-    /**
-     * <p>
-     * Initializes the application. This is the only method an application is
-     * required to implement. It's called by the framework and it should perform
-     * whatever initialization tasks the application needs to perform.
-     * </p>
-     * 
-     * <p>
-     * In this case we create the main window, the display, the grid to hold the
-     * buttons, and the buttons themselves.
-     * </p>
-     */
+    // Application initialization creates UI and connects it to business logic
     public void init() {
 
-        // Create a new layout for the components used by the calculator
-        final GridLayout layout = new GridLayout(4, 5);
-
-        // Styling: fix grids size, cells will become equally sized
-        layout.setWidth("15em");
-        layout.setHeight("18em");
-        // Styling: leave margin around layout
-        layout.setMargin(true);
-
-        // Create a new label component for displaying the result
-        display = new Label(Double.toString(current));
-        display.setCaption("Result");
+        // Place the layout to a floating dialog inside the browser main window
+        setMainWindow(new Window("Calculator Application"));
+        getMainWindow().addWindow(new Window("Calc", layout));
 
-        // Place the label to the top of the previously created grid.
+        // Create and add the components to the layout
         layout.addComponent(display, 0, 0, 3, 0);
-
-        // Create the buttons and place them in the grid
-        for (int i = 0; i < captions.length; i++) {
-            final Button button = new Button(captions[i], this);
-            button.setSizeFull(); // use all size given by grid
+        for (String caption : new String[] { "7", "8", "9", "/", "4", "5", "6",
+                "*", "1", "2", "3", "-", "0", "=", "C", "+" }) {
+            Button button = new Button(caption, new Button.ClickListener() {
+                public void buttonClick(Button.ClickEvent event) {
+
+                    // On button click, calculate and show the result
+                    display.setValue(calculate(event.getButton()));
+                }
+            });
             layout.addComponent(button);
         }
-
-        // Create the main window with a caption and add it to the application.
-        addWindow(new Window("Calculator", layout));
-
     }
 
-    /**
-     * <p>
-     * The button listener method called any time a button is pressed. This
-     * method catches all button presses, figures out what the user wanted the
-     * application to do, and updates the UI accordingly.
-     * </p>
-     * 
-     * <p>
-     * The button click event passed to this method contains information about
-     * which button was pressed. If it was a number, the currently edited number
-     * is updated. If it was something else, the requested operation is
-     * performed. In either case the display label is updated to include the
-     * outcome of the button click.
-     * </p>
-     * 
-     * @param event
-     *            the button click event specifying which button was pressed
-     */
-    public void buttonClick(Button.ClickEvent event) {
-
-        try {
-            // Number button pressed
+    // Calculator "business logic" implemented here to keep the example minimal
+    private double calculate(Button buttonClicked) {
+        char requestedOperation = buttonClicked.getCaption().charAt(0);
+        if ('0' <= requestedOperation && requestedOperation <= '9') {
             current = current * 10
-                    + Double.parseDouble(event.getButton().getCaption());
-            display.setValue(Double.toString(current));
-        } catch (final java.lang.NumberFormatException e) {
-
-            // Operation button pressed
-            if (operation.equals("+")) {
-                stored += current;
-            }
-            if (operation.equals("-")) {
-                stored -= current;
-            }
-            if (operation.equals("*")) {
-                stored *= current;
-            }
-            if (operation.equals("/")) {
-                stored /= current;
-            }
-            if (operation.equals("C")) {
-                stored = current;
-            }
-            if (event.getButton().getCaption().equals("C")) {
-                stored = 0.0;
-            }
-            operation = event.getButton().getCaption();
-            current = 0.0;
-            display.setValue(Double.toString(stored));
+                    + Double.parseDouble("" + requestedOperation);
+            return current;
+        }
+        switch (lastOperationRequested) {
+        case '+':
+            stored += current;
+            break;
+        case '-':
+            stored -= current;
+            break;
+        case '/':
+            stored /= current;
+            break;
+        case '*':
+            stored *= current;
+            break;
+        case 'C':
+            stored = current;
+            break;
+        }
+        lastOperationRequested = requestedOperation;
+        current = 0.0;
+        if (requestedOperation == 'C') {
+            stored = 0.0;
         }
+        return stored;
     }
 }