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.ui.Label; import com.google.gwt.user.client.ui.RootPanel; 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.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 StockWatcher implements EntryPoint { private static final int REFRESH_INTERVAL = 5000; private VerticalPanel mainPanel = new VerticalPanel(); private FlexTable stocksFlexTable = new FlexTable(); private HorizontalPanel addPanel = new HorizontalPanel(); private TextBox newSymbolTextBox = new TextBox(); private Button addStockButton = new Button("Add"); private Label lastUpdatedLabel = new Label(); private ArrayList<String> stocks = new ArrayList<String>(); /** * Entry point method. */ public void onModuleLoad() { //Create table for stock data. stocksFlexTable.setText(0, 0, "Symbol"); stocksFlexTable.setText(0, 1, "Price"); stocksFlexTable.setText(0, 2, "Change"); stocksFlexTable.setText(0, 3, "Remove"); //Assemble Add Stock panel. addPanel.add(newSymbolTextBox); addPanel.add(addStockButton); //Assemble Main panel. mainPanel.add(stocksFlexTable); mainPanel.add(addPanel); mainPanel.add(lastUpdatedLabel); //Associate the Main panel with the HTML host page. RootPanel.get("stockList").add(mainPanel); //Move cursor focus to the input box. newSymbolTextBox.setFocus(true); // Setup timer to refresh list automatically. 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(); } }); // Listen for keyboard events in the input box. newSymbolTextBox.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() { final String symbol = newSymbolTextBox.getText().toUpperCase().trim(); newSymbolTextBox.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."); newSymbolTextBox.selectAll(); return; } newSymbolTextBox.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 = stocksFlexTable.getRowCount(); stocks.add(symbol); stocksFlexTable.setText(row, 0, symbol); // TODO Add a button to remove this stock from the table. Button removeStockButton = new Button("x"); removeStockButton.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { int removedIndex = stocks.indexOf(symbol); stocks.remove(removedIndex); stocksFlexTable.removeRow(removedIndex + 1); } }); stocksFlexTable.setWidget(row, 3, removeStockButton); // TODO Get the stock price. refreshWatchList(); } private void refreshWatchList() { // TODO Auto-generated method stub 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); } /** * Update the Price and Change fields all the rows in the stock table. * * @param prices Stock data for all rows. */ 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. DateTimeFormat dateFormat = DateTimeFormat.getFormat(DateTimeFormat.PredefinedFormat.DATE_TIME_MEDIUM); lastUpdatedLabel.setText("Last update : " + dateFormat.format(new Date())); } /** * Update a single row in the stock table. * * @param price Stock data for a single row. */ private void updateTable(StockPrice stockPrice) { // TODO Auto-generated method stub // Make sure the stock is still in the stock table. if (!stocks.contains(stockPrice.getSymbol())) { return; } int row = stocks.indexOf(stockPrice.getSymbol()) + 1; // Format the data in the Price and Change fields. String priceText = NumberFormat.getFormat("#,##0.00").format(stockPrice.getPrice()); NumberFormat changeFormat = NumberFormat.getFormat("+#,##0.00;-#,##0.00"); String changeText = changeFormat.format(stockPrice.getChange()); String changePercentText = changeFormat.format(stockPrice.getChangePercent()); // Populate the Price and Change fields with new data. stocksFlexTable.setText(row, 1, priceText); stocksFlexTable.setText(row, 2, changeText + " (" + changePercentText + "%)"); } }