Java tutorial
package com.google.gwt.sample.stockwatcher.client; import java.util.ArrayList; import java.util.Date; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.user.client.Random; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.Window; import com.google.gwt.user.client.ui.Button; import com.google.gwt.user.client.ui.FlexTable; import com.google.gwt.user.client.ui.HorizontalPanel; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.RootPanel; import com.google.gwt.user.client.ui.TextBox; import com.google.gwt.user.client.ui.VerticalPanel; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.event.dom.client.KeyCodes; import com.google.gwt.event.dom.client.KeyDownEvent; import com.google.gwt.event.dom.client.KeyDownHandler; import com.google.gwt.i18n.client.DateTimeFormat; import com.google.gwt.i18n.client.NumberFormat; public class StockWatch implements EntryPoint { /** ** Layout Objects **/ private VerticalPanel mainPanel = new VerticalPanel(); private FlexTable stockTable = new FlexTable(); private HorizontalPanel addPanel = new HorizontalPanel(); private TextBox newSymbolBox = new TextBox(); private Button addStockButton = new Button("Add"); private Label lastUpdatedLabel = new Label(); private ArrayList<String> stocks = new ArrayList<String>(); private static final int REFRESH_INTERVAL = 5000; /** ** ENTRY POINT **/ public void onModuleLoad() { // TODO Create table for stock data. stockTable.setText(0, 0, "Symbol"); stockTable.setText(0, 1, "Price"); stockTable.setText(0, 2, "Change"); stockTable.setText(0, 3, "remove"); stockTable.setCellPadding(6); stockTable.getRowFormatter().addStyleName(0, "watchListHeader"); stockTable.addStyleName("watchList"); stockTable.getCellFormatter().addStyleName(0, 1, "watchListNumericColumn"); stockTable.getCellFormatter().addStyleName(0, 2, "watchListNumericColumn"); stockTable.getCellFormatter().addStyleName(0, 3, "watchListRemoveColumn"); // TODO Assemble Add Stock panel. addPanel.add(newSymbolBox); addPanel.add(addStockButton); addPanel.addStyleName("addPanel"); // TODO Assemble Main panel. mainPanel.add(stockTable); mainPanel.add(addPanel); mainPanel.add(lastUpdatedLabel); // TODO Associate the Main panel with the HTML host page. RootPanel.get("stocklist").add(mainPanel); // TODO Move cursor focus to the input box. newSymbolBox.setFocus(true); // TODO Set up timer to automatically refresh list Timer refreshTimer = new Timer() { @Override public void run() { refreshWatchList(); } }; refreshTimer.scheduleRepeating(REFRESH_INTERVAL); // Listen for mouse events on the Add button. addStockButton.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { addStock(); } }); newSymbolBox.addKeyDownHandler(new KeyDownHandler() { public void onKeyDown(KeyDownEvent event) { if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) { addStock(); } } }); } /** * Add stock to FlexTable. Executed when the user clicks the addStockButton * or presses enter in the newSymbolTextBox. */ private void addStock() { // gets the text from the box, makes it uppercase and takes away leading // and trailing space. final String symbol = newSymbolBox.getText().toUpperCase().trim(); newSymbolBox.setFocus(true); // Stock code must be between 1 and 10 chars that are numbers, letters, // or dots. if (!symbol.matches("^[0-9A-Z\\.]{1,10}$")) { Window.alert("'" + symbol + "' is not a valid symbol."); newSymbolBox.selectAll(); return; } newSymbolBox.setText(""); // TODO Don't add the stock if it's already in the table. if (stocks.contains(symbol)) { return; } // TODO Add the stock to the table int row = stockTable.getRowCount(); stocks.add(symbol); stockTable.setText(row, 0, symbol); stockTable.setWidget(row, 2, new Label()); stockTable.getCellFormatter().addStyleName(row, 1, "watchListNumericColumn"); stockTable.getCellFormatter().addStyleName(row, 2, "watchListNumericColumn"); stockTable.getCellFormatter().addStyleName(row, 3, "watchListRemoveColumn"); // TODO Add a button to remove this stock from the table. Button removeStockButton = new Button("x"); removeStockButton.addStyleDependentName("remove"); removeStockButton.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { int removedIndex = stocks.indexOf(symbol); stocks.remove(removedIndex); stockTable.removeRow(removedIndex + 1); } }); stockTable.setWidget(row, 3, removeStockButton); // TODO Get the stock price. refreshWatchList(); } private void refreshWatchList() { final double MAX_PRICE = 100.0; // $100.00 final double MAX_PRICE_CHANGE = 0.02; // +/- 2% StockPrice[] prices = new StockPrice[stocks.size()]; for (int i = 0; i < stocks.size(); i++) { double price = Random.nextDouble() * MAX_PRICE; double change = price * MAX_PRICE_CHANGE * (Random.nextDouble() * 2.0 - 1.0); prices[i] = new StockPrice(stocks.get(i), price, change); } updateTable(prices); } @SuppressWarnings("deprecation") private void updateTable(StockPrice[] prices) { // TODO Auto-generated method stub for (int i = 0; i < prices.length; i++) { updateTable(prices[i]); // Display timestamp showing last refresh. lastUpdatedLabel .setText("Last update : " + DateTimeFormat.getMediumDateTimeFormat().format(new Date())); } } /** * Update a single row in the stock table. * * @param price * Stock data for a single row. */ private void updateTable(StockPrice price) { // Make sure the stock is still in the stock table. if (!stocks.contains(price.getSymbol())) { return; } int row = stocks.indexOf(price.getSymbol()) + 1; // Format the data in the Price and Change fields. String priceText = NumberFormat.getFormat("#,##0.00").format(price.getPrice()); NumberFormat changeFormat = NumberFormat.getFormat("+#,##0.00;-#,##0.00"); String changeText = changeFormat.format(price.getChange()); String changePercentText = changeFormat.format(price.getChangePercent()); // Populate the Price and Change fields with new data. stockTable.setText(row, 1, priceText); Label changeWidget = (Label) stockTable.getWidget(row, 2); changeWidget.setText(changeText + " (" + changePercentText + "%)"); // Change the color of text in the Change field based on its value. String changeStyleName = "noChange"; if (price.getChangePercent() < -0.1f) { changeStyleName = "negativeChange"; } else if (price.getChangePercent() > 0.1f) { changeStyleName = "positiveChange"; } changeWidget.setStyleName(changeStyleName); } }