Initial commit (ceef8404) · Commits · examples / Java Examples in a Nutshell

AllComponents.java

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		// This example is from _Java Examples in a Nutshell_. (http://www.oreilly.com)
		// Copyright (c) 1997 by David Flanagan
		// This example is provided WITHOUT ANY WARRANTY either expressed or implied.
		// You may study, use, modify, and distribute it for non-commercial purposes.
		// For any commercial use, see http://www.davidflanagan.com/javaexamples

		import java.awt.*;
		import java.awt.event.*;

		/** A program that uses all the standard AWT components */
		public class AllComponents extends Frame implements ActionListener {
		TextArea textarea; // Events messages will be displayed here.

		/** Create the whole GUI, and set up event listeners */
		public AllComponents(String title) {
		super(title); // set frame title.

		// Arrange to detect window close events
		this.addWindowListener(new WindowAdapter() {
		public void windowClosing(WindowEvent e) { System.exit(0); }
		});

		// Set a default font
		this.setFont(new Font("SansSerif", Font.PLAIN, 12));

		// Create the menubar. Tell the frame about it.
		MenuBar menubar = new MenuBar();
		this.setMenuBar(menubar);

		// Create the file menu. Add to menubar.
		Menu file = new Menu("File");
		menubar.add(file);

		// Create two items for the file menu, setting their label, shortcut,
		// action command and listener. Add them to File menu.
		// Note that we use the frame itself as the action listener
		MenuItem open = new MenuItem("Open", new MenuShortcut(KeyEvent.VK_O));
		open.setActionCommand("open");
		open.addActionListener(this);
		file.add(open);
		MenuItem quit = new MenuItem("Quit", new MenuShortcut(KeyEvent.VK_Q));
		quit.setActionCommand("quit");
		quit.addActionListener(this);
		file.add(quit);

		// Create Help menu; add an item; add to menubar
		// Display the help menu in a special reserved place.
		Menu help = new Menu("Help");
		menubar.add(help);
		menubar.setHelpMenu(help);

		// Create and add an item to the Help menu
		MenuItem about = new MenuItem("About", new MenuShortcut(KeyEvent.VK_A));
		about.setActionCommand("about");
		about.addActionListener(this);
		help.add(about);

		// Now that we've done the menu, we can begin work on the contents of
		// the frame. Assign a BorderLayout manager with margins for this frame.
		this.setLayout(new BorderLayout(10, 10));

		// Create two panels to contain two columns of components. Use our custom
		// ColumnLayout layout manager for each. Add them on the west and
		// center of the frame's border layout
		Panel column1 = new Panel();
		column1.setLayout(new ColumnLayout(5, 10, 2, ColumnLayout.LEFT));
		this.add(column1, "West");
		Panel column2 = new Panel();
		column2.setLayout(new ColumnLayout(5, 10, 2, ColumnLayout.LEFT));
		this.add(column2, "Center");

		// Create a panel to contain the buttons at the bottom of the window
		// Give it a FlowLayout layout manager, and add it along the south border
		Panel buttonbox = new Panel();
		buttonbox.setLayout(new FlowLayout(FlowLayout.CENTER, 100, 10));
		this.add(buttonbox, "South");

		// Create pushbuttons and add them to the buttonbox
		Button okay = new Button("Okay");
		Button cancel = new Button("Cancel");
		buttonbox.add(okay);
		buttonbox.add(cancel);

		// Handle events on the buttons
		ActionListener buttonlistener = new ActionListener() {
		public void actionPerformed(ActionEvent e) {
		textarea.append("You clicked: " +
		((Button)e.getSource()).getLabel() + "\n");
		}
		};
		okay.addActionListener(buttonlistener);
		cancel.addActionListener(buttonlistener);

		// Now start filling the left column.
		// Create a 1-line text field and add to left column, with a label
		TextField textfield = new TextField(15);
		column1.add(new Label("Name:"));
		column1.add(textfield);

		// Handle events on the TextField
		textfield.addActionListener(new ActionListener() {
		public void actionPerformed(ActionEvent e) {
		textarea.append("Your name is: " +
		((TextField)e.getSource()).getText() + "\n");
		}
		});
		textfield.addTextListener(new TextListener() {
		public void textValueChanged(TextEvent e) {
		textarea.append("You have typed: " +
		((TextField)e.getSource()).getText() + "\n");
		}
		});

		// Create a dropdown list or option menu of choices
		Choice choice = new Choice();
		choice.addItem("red");
		choice.addItem("green");
		choice.addItem("blue");
		column1.add(new Label("Favorite color:"));
		column1.add(choice);

		// Handle events on this choice
		choice.addItemListener(new ItemListener() {
		public void itemStateChanged(ItemEvent e) {
		textarea.append("Your favorite color is: " + e.getItem() + "\n");
		}
		});

		// Create checkboxes, and group them in a CheckboxGroup to give them
		// "radio button" behavior.
		CheckboxGroup checkbox_group = new CheckboxGroup();
		Checkbox[] checkboxes = new Checkbox[3];
		checkboxes[0] = new Checkbox("vanilla", checkbox_group, false);
		checkboxes[1] = new Checkbox("chocolate", checkbox_group, true);
		checkboxes[2] = new Checkbox("strawberry", checkbox_group, false);
		column1.add(new Label("Favorite flavor:"));
		for(int i = 0; i < checkboxes.length; i++) column1.add(checkboxes[i]);

		// Handle events on the checkboxes
		ItemListener checkbox_listener = new ItemListener() {
		public void itemStateChanged(ItemEvent e) {
		textarea.append("Your favorite flavor is: " +
		((Checkbox)e.getItemSelectable()).getLabel() + "\n");
		}
		};
		for(int i = 0; i < checkboxes.length; i++)
		checkboxes[i].addItemListener(checkbox_listener);

		// Create a list of choices.
		List list = new List(4, true);
		list.addItem("Java"); list.addItem("C"); list.addItem("C++");
		list.addItem("Smalltalk"); list.addItem("Lisp");
		list.addItem("Modula-3"); list.addItem("Forth");
		column1.add(new Label("Favorite languages:"));
		column1.add(list);
		// Handle events on this list
		list.addItemListener(new ItemListener() {
		public void itemStateChanged(ItemEvent e) {
		textarea.append("Your favorite languages are: ");
		String[] languages = ((List)e.getItemSelectable()).getSelectedItems();
		for(int i = 0; i < languages.length; i++) {
		if (i > 0) textarea.append(",");
		textarea.append(languages[i]);
		}
		textarea.append("\n");
		}
		});

		// Create a multi-line text area in column 2
		textarea = new TextArea(6, 40);
		textarea.setEditable(false);
		column2.add(new Label("Messages"));
		column2.add(textarea);

		// Create a scrollpane that displays portions of a larger component
		ScrollPane scrollpane = new ScrollPane();
		scrollpane.setSize(300, 150);
		column2.add(new Label("Scrolling Window"));
		column2.add(scrollpane);

		// Create a custom MultiLineLabel with a really big font and make it
		// a child of the ScrollPane container
		String message =
		"/*************************************************\n" +
		" * AllComponents.java *\n" +
		" * Written by David Flanagan *\n" +
		" * Copyright (c) 1997 by O'Reilly & Associates *\n" +
		" * *\n" +
		" *************************************************/\n";
		MultiLineLabel biglabel = new MultiLineLabel(message);
		biglabel.setFont(new Font("Monospaced", Font.BOLD + Font.ITALIC, 24));
		scrollpane.add(biglabel);
		}

		/** This is the action listener method that the menu items invoke */
		public void actionPerformed(ActionEvent e) {
		String command = e.getActionCommand();
		if (command.equals("quit")) {
		YesNoDialog d = new YesNoDialog(this, "Really Quit?",
		"Are you sure you want to quit?",
		"Yes", "No", null);
		d.addActionListener(new ActionListener() {
		public void actionPerformed(ActionEvent e) {
		if (e.getActionCommand().equals("yes")) System.exit(0);
		else textarea.append("Quit not confirmed\n");
		}
		});
		d.show();
		}
		else if (command.equals("open")) {
		FileDialog d = new FileDialog(this, "Open File", FileDialog.LOAD);
		d.show(); // display the dialog and block until answered
		textarea.append("You selected file: " + d.getFile() + "\n");
		d.dispose();
		}
		else if (command.equals("about")) {
		InfoDialog d = new InfoDialog(this, "About",
		"This demo was written by David Flanagan\n" +
		"Copyright (c) 1997 O'Reilly & Associates");
		d.show();
		}
		}

		public static void main(String[] args) {
		Frame f = new AllComponents("AWT Demo");
		f.pack();
		f.show();
		}
		}

Averager.java

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		// This example is from _Java Examples in a Nutshell_. (http://www.oreilly.com)
		// Copyright (c) 1997 by David Flanagan
		// This example is provided WITHOUT ANY WARRANTY either expressed or implied.
		// You may study, use, modify, and distribute it for non-commercial purposes.
		// For any commercial use, see http://www.davidflanagan.com/javaexamples

		/**
		* A class to compute the running average of numbers passed to it
		**/
		public class Averager {
		// Private fields to hold the current state.
		private int n = 0;
		private double sum = 0.0, sumOfSquares = 0.0;

		/**
		* This method adds a new datum into the average.
		**/
		public void addDatum(double x) {
		n++;
		sum += x;
		sumOfSquares += x * x;
		}

		/** This method returns the average of all numbers passed to addDatum() */
		public double getAverage() { return sum / n; }

		/** This method returns the standard deviation of the data */
		public double getStandardDeviation() {
		return Math.sqrt(((sumOfSquares - sum*sum/n)/n));
		}

		/** This method returns the number of numbers passed to addDatum() */
		public double getNum() { return n; }

		/** This method returns the sum of all numbers passed to addDatum() */
		public double getSum() { return sum; }

		/** This method returns the sum of the squares of all numbers. */
		public double getSumOfSquares() { return sumOfSquares; }

		/** This method resets the Averager object to begin from scratch */
		public void reset() { n = 0; sum = 0.0; sumOfSquares = 0.0; }

		/**
		* This nested class is a simple test program we can use to check that
		* our code works okay.
		**/
		public static class Test {
		public static void main(String args[]) {
		Averager a = new Averager();
		for(int i = 1; i <= 100; i++) a.addDatum(i);
		System.out.println("Average: " + a.getAverage());
		System.out.println("Standard Deviation: " + a.getStandardDeviation());
		System.out.println("N: " + a.getNum());
		System.out.println("Sum: " + a.getSum());
		System.out.println("Sum of squares: " + a.getSumOfSquares());
		}
		}
		}

Bank.java

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		// This example is from _Java Examples in a Nutshell_. (http://www.oreilly.com)
		// Copyright (c) 1997 by David Flanagan
		// This example is provided WITHOUT ANY WARRANTY either expressed or implied.
		// You may study, use, modify, and distribute it for non-commercial purposes.
		// For any commercial use, see http://www.davidflanagan.com/javaexamples

		import java.rmi.*;
		import java.util.Vector;

		/**
		* This class is a placeholder that simply contains other classes and
		* for interfaces remote banking.
		**/
		public class Bank {
		/**
		* This is the interface that defines the exported methods of the
		* bank server.
		**/
		public interface RemoteBank extends Remote {
		/** Open a new account, with the specified name and password */
		public void openAccount(String name, String password)
		throws RemoteException, BankingException;

		/** Close the named account */
		public FunnyMoney closeAccount(String name, String password)
		throws RemoteException, BankingException;

		/** Deposit money into the named account */
		public void deposit(String name, String password, FunnyMoney money)
		throws RemoteException, BankingException;

		/** Withdraw the specified amount of money from the named account */
		public FunnyMoney withdraw(String name, String password, int amount)
		throws RemoteException, BankingException;

		/** Return the amount of money in the named account */
		public int getBalance(String name, String password)
		throws RemoteException, BankingException;

		/**
		* Return a Vector of Strings that list the transaction history
		* of the named account
		**/
		public Vector getTransactionHistory(String name, String password)
		throws RemoteException, BankingException;
		}

		/**
		* This simple class represents a monetary amount. This implementation
		* is really nothing more than a wrapper around an integer. It is a useful
		* to demonstrate that RMI can accept arbitrary non-String objects as
		* arguments and return them as values, as long as they are Serializable.
		* A more complete implementation of this FunnyMoney class might bear
		* a serial number, a digital signature, and other security features to
		* ensure that it is unique and non-forgable.
		**/
		public static class FunnyMoney implements java.io.Serializable {
		public int amount;
		public FunnyMoney(int amount) { this.amount = amount; }
		}

		/**
		* This is a type of exception used to represent exceptional conditions
		* related to banking, such as "Insufficient Funds" and "Invalid Password"
		**/
		public static class BankingException extends Exception {
		public BankingException(String msg) { super(msg); }
		}

		/**
		* This class is a simple stand-alone client program that interacts
		* with a RemoteBank server. It invokes different RemoteBank methods
		* depending on its command-line arguments, and demonstrates just how
		* simple it is to interact with a server using RMI.
		**/
		public static class Client {
		public static void main(String[] args) {
		try {
		// Set the standard RMI security manager so that we can safely load
		// untrusted RemoteBank stub code over the network.
		System.setSecurityManager(new RMISecurityManager());

		// Figure out what RemoteBank to connect to by reading a system
		// property (specified on the command line with a -D option to java)
		// or, if it is not defined, use a default URL. Note that by default
		// this client tries to connect to a server on the local machine
		String url = System.getProperty("bank", "rmi:///FirstRemote");

		// Now look up that RemoteBank server using the Naming object, which
		// contacts the rmiregistry server. Given the url, this call returns
		// a RemoteBank object whose methods may be invoked remotely
		RemoteBank bank = (RemoteBank) Naming.lookup(url);

		// Convert the user's command to lower case
		String cmd = args[0].toLowerCase();

		// Now, go test the command against a bunch of possible options
		if (cmd.equals("open")) { // Open an account
		bank.openAccount(args[1], args[2]);
		System.out.println("Account opened.");
		}
		else if (cmd.equals("close")) { // Close an account
		FunnyMoney money = bank.closeAccount(args[1], args[2]);
		// Note that FunnyMoney currency is denominated in wooden nickels
		System.out.println(money.amount+" wooden nickels returned to you.");
		System.out.println("Thanks for banking with us.");
		}
		else if (cmd.equals("deposit")) { // Deposit money
		FunnyMoney money = new FunnyMoney(Integer.parseInt(args[3]));
		bank.deposit(args[1], args[2], money);
		System.out.println("Deposited " + money.amount + " wooden nickels.");
		}
		else if (cmd.equals("withdraw")) { // Withdraw money
		FunnyMoney money = bank.withdraw(args[1], args[2],
		Integer.parseInt(args[3]));
		System.out.println("Withdrew " + money.amount + " wooden nickels.");
		}
		else if (cmd.equals("balance")) { // Check account balance
		int amt = bank.getBalance(args[1], args[2]);
		System.out.println("You have "+amt+" wooden nickels in the bank.");
		}
		else if (cmd.equals("history")) { // Get transaction history
		Vector transactions = bank.getTransactionHistory(args[1], args[2]);
		for(int i = 0; i < transactions.size(); i++)
		System.out.println(transactions.elementAt(i));
		}
		else System.out.println("Unknown command");
		}
		// Catch and display RMI exceptions
		catch (RemoteException e) { System.err.println(e); }
		// Catch and display Banking related exceptions
		catch (BankingException e) { System.err.println(e.getMessage()); }
		// Other exceptions are probably user syntax errors, so show usage.
		catch (Exception e) {
		System.err.println(e);
		System.err.println("Usage: java [-Dbank=<url>] Bank$Client " +
		"<cmd> <name> <password> [<amount>]");
		System.err.println("where cmd is: open, close, deposit, " +
		"withdraw, balance, history");
		}
		}
		}
		}

BorderLayoutExample.html

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		<APPLET CODE="BorderLayoutExample.class" WIDTH=350 HEIGHT=200></APPLET>

BorderLayoutExample.java

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		// This example is from _Java Examples in a Nutshell_. (http://www.oreilly.com)
		// Copyright (c) 1997 by David Flanagan
		// This example is provided WITHOUT ANY WARRANTY either expressed or implied.
		// You may study, use, modify, and distribute it for non-commercial purposes.
		// For any commercial use, see http://www.davidflanagan.com/javaexamples

		import java.applet.*;
		import java.awt.*;

		public class BorderLayoutExample extends Applet {
		String[] borders = {"North", "East", "South", "West", "Center"};
		public void init() {
		// Create and specify a BorderLayout layout manager that leaves
		// 10 pixels of horizontal and vertical space between components
		this.setLayout(new BorderLayout(10, 10));
		for(int i = 0; i < 5; i++) {
		// Swap the order of these arguments in Java 1.1
		this.add(borders[i], new Button(borders[i]));
		}
		}
		}