// Question:
// how is the ArrayIndexOutOfBoundsException thrown by f() ?public class ExceptionThrown {public static void f()    {int[] a = new int[10];a[10] = 10;System.out.println("hello");}public static void g() {f();}public static void h() {int i = 10;if (i < 100) {g();}}public static void k() {try {g();} catch (NullPointerException e) {System.out.println("k()");}}public static void main (String[] args) {try {k();} catch (ArrayIndexOutOfBoundsException e) {System.out.println("Exception Caught");            System.out.println(e);            e.printStackTrace();}}
}

public class A {public void f() throws AException {}
}public class A1 extends A {public void f() {}    // works okpublic void f() throws AException {}    // works okpublic void f() throws AException, BException {}    // Error: Exception BException is not compatible with throws clause in A.f()
}

public class InputStreamTest {public static void main(String[] args) {System.out.println("Ready to read in: ");byte[] buffer = new byte[1024];try {int len = System.in.read(buffer);    // how many bytes read inString s = new String(buffer, 0 ,len);    // start at 0, with length lenSystem.out.println("read in " + len + " bytes.");System.out.println(s);System.out.println("length of s: " + s.length());} catch (IOException e) {e.printStackTrace();}}
}

public static void main(String[] args) {System.out.println("prompt");byte[] buffer = new byte[10];for(int i = 0; i < buffer.length; i++) {buffer[i] = (byte) i;}try {FileOutputStream out = new FileOutputStream("a.dat");out.write(buffer);// a file called a.dat will be created of size 10 bytes} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}} 

    public static void main(String[] args) {System.out.println("prompt");// data stream: input/output the primitive types value
        DataOutputStream out;try {out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("a.dat")));// nested stream -- bytes from FileOutputStream to BufferedOutputStream, to DataOutputStream
//            int i = 0xcafebabe;    // hexint i = 123456;    // what is written in the file is binary
            out.writeInt(i);out.close();DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream("a.dat")));int j = in.readInt();in.close();System.out.println(j);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}

    public static void main(String[] args) {System.out.println("prompt");try {PrintWriter out = new PrintWriter (new BufferedWriter(new OutputStreamWriter(new FileOutputStream("a.txt"))));// FileOutputStream: bytes// OutputStreamWriter: the bridge between stream and writerint i = 123456;out.println(i);out.close();// BufferedReaderBufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream("src/ReaderWriter.java")));String line;while ((line = in.readLine()) != null) {// read in line by line
                System.out.println(line);}} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}

public static void main(String[] args) {try {// construct connectionSocket socket = new Socket(InetAddress.getByName("localhost"), 12345);PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())));out.println("Hello");    // write Helloout.flush();    // kinda like refresh// Read inBufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));String line;line = in.readLine();System.out.println(line);out.close();socket.close();} catch (IOException e) {e.printStackTrace();}}

public static void main(String[] args) {Student s1 = new Student("John", 18, 5);System.out.println("s1" + s1);try {ObjectOutputStream out;out = new ObjectOutputStream (new FileOutputStream("obj.dat"));out.writeObject(s1);out.close();} catch (IOException e) {e.printStackTrace();}ObjectInputStream in;try {in = new ObjectInputStream(new FileInputStream("obj.dat"));Student s2 = (Student)in.readObject();System.out.println("s2" + s2);in.close();} catch (IOException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();}}

package castle;public class Room {public String description;public Room northExit;public Room southExit;public Room eastExit;public Room westExit;public Room(String description) {this.description = description;}public void setExits(Room north, Room east, Room south, Room west) {if(north != null)northExit = north;if(east != null)eastExit = east;if(south != null)southExit = south;if(west != null)westExit = west;}@Overridepublic String toString(){return description;}
}

package castle;import java.util.Scanner;public class Game {private Room currentRoom;public Game() {createRooms();}private void createRooms(){Room outside, lobby, pub, study, bedroom;//    制造房间outside = new Room("城堡外");lobby = new Room("大堂");pub = new Room("小酒吧");study = new Room("书房");bedroom = new Room("卧室");//    初始化房间的出口outside.setExits(null, lobby, study, pub);lobby.setExits(null, null, null, outside);pub.setExits(null, outside, null, null);study.setExits(outside, bedroom, null, null);bedroom.setExits(null, null, null, study);currentRoom = outside;  //    从城堡门外开始
    }private void printWelcome() {System.out.println();System.out.println("欢迎来到城堡！");System.out.println("这是一个超级无聊的游戏。");System.out.println("如果需要帮助，请输入 'help' 。");System.out.println();System.out.println("现在你在" + currentRoom);System.out.print("出口有：");if(currentRoom.northExit != null)System.out.print("north ");if(currentRoom.eastExit != null)System.out.print("east ");if(currentRoom.southExit != null)System.out.print("south ");if(currentRoom.westExit != null)System.out.print("west ");System.out.println();}// 以下为用户命令private void printHelp() {System.out.print("迷路了吗？你可以做的命令有：go bye help");System.out.println("如：\tgo east");}private void goRoom(String direction) {Room nextRoom = null;if(direction.equals("north")) {nextRoom = currentRoom.northExit;}if(direction.equals("east")) {nextRoom = currentRoom.eastExit;}if(direction.equals("south")) {nextRoom = currentRoom.southExit;}if(direction.equals("west")) {nextRoom = currentRoom.westExit;}if (nextRoom == null) {System.out.println("那里没有门！");}else {currentRoom = nextRoom;System.out.println("你在" + currentRoom);System.out.print("出口有: ");if(currentRoom.northExit != null)System.out.print("north ");if(currentRoom.eastExit != null)System.out.print("east ");if(currentRoom.southExit != null)System.out.print("south ");if(currentRoom.westExit != null)System.out.print("west ");System.out.println();}}public static void main(String[] args) {Scanner in = new Scanner(System.in);Game game = new Game();game.printWelcome();while ( true ) {String line = in.nextLine();String[] words = line.split(" ");if ( words[0].equals("help") ) {game.printHelp();} else if (words[0].equals("go") ) {game.goRoom(words[1]);} else if ( words[0].equals("bye") ) {break;}}System.out.println("感谢您的光临。再见！");in.close();}}

System.out.println("你在" + currentRoom);
System.out.print("出口有: ");
if(currentRoom.northExit != null)System.out.print("north ");
if(currentRoom.eastExit != null)System.out.print("east ");
if(currentRoom.southExit != null)System.out.print("south ");
if(currentRoom.westExit != null)System.out.print("west ");
System.out.println();

public String getExitSDesc() {StringBuffer sb = new StringBuffer();if(northExit != null)sb.append("north ");if(eastExit != null)sb.append("east ");if(southExit != null)sb.append("south ");if(westExit != null)sb.append("west ");return sb.toString();}

public Room moveToNextRoom(String direction) {Room nextRoom = null;if(direction.equals("north")) {nextRoom = northExit;}if(direction.equals("east")) {nextRoom = eastExit;}if(direction.equals("south")) {nextRoom = southExit;}if(direction.equals("west")) {nextRoom = westExit;}return nextRoom;
}

public void setExit(String dir, Room room) {exits.put(dir, room);
}

outside.setExit("east", lobby);
outside.setExit("south", study);
outside.setExit("west", pub);
lobby.setExit("west", outside);
pub.setExit("east", outside);
study.setExit("north", outside);
study.setExit("east", bedroom);
bedroom.setExit("west", study);// extended exits
lobby.setExit("up", pub);
pub.setExit("down", lobby);

while ( true ) {String line = in.nextLine();String[] words = line.split(" ");if ( words[0].equals("help") ) {game.printHelp();} else if (words[0].equals("go") ) {game.goRoom(words[1]);} else if (words[0].equals("bye") ) {break;}readInCmd();
}

    public void play() {Scanner in = new Scanner(System.in);while ( true ) {String line = in.nextLine();String[] words = line.split(" ");CmdHandler handler = handlers.get(words[0]);if (handler != null) {handler.cmdHandling();if (handler instanceof ByeHandler) {break;} else if (handler instanceof GoHandler) {if (words.length == 2) {((GoHandler)handler).cmdHandling(words[1]);} else {System.out.println("Invalid Command (Usage: go dir)\n");}}} else {System.out.println("Invalid Command\n");}}in.close();}

public class CmdHandler {public void cmdHandling() {}
}public class GoHandler extends CmdHandler{private Game game;public GoHandler(Game game) {this.game = game;}public void cmdHandling(String dir) {game.goRoom(dir);}
}public class HelpHandler extends CmdHandler{public void cmdHandling() {System.out.println("迷路了吗？你可以做的命令有：go bye help");System.out.println("如：\tgo east");}
}public class ByeHandler extends CmdHandler{public void cmdHandling() {System.out.println("感谢您的光临。再见！");}
}

// add button
JButton btnStep = new JButton("下一步");
frame.add(btnStep, BorderLayout.NORTH);    // which component, and where
btnStep.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {step();frame.repaint();}
});    

    public static void main(String[] args) {JFrame frame = new JFrame();JTable table = new JTable(new CurriculumData());// JTable cannot display all of its contentJScrollPane panel = new JScrollPane(table);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.add(panel);frame.setSize(400, 400);frame.setVisible(true);}    

import javax.swing.event.TableModelListener;
import javax.swing.table.TableModel;public class CurriculumData implements TableModel {private String[] title = {"周一","周二","周三","周四","周五","周六","周日"};private String[][] curriculum = new String[8][7];@Overridepublic int getRowCount() {return 8;}@Overridepublic int getColumnCount() {return 7;}@Overridepublic String getColumnName(int columnIndex) {// the name of each columnreturn title[columnIndex];}@Overridepublic Class<?> getColumnClass(int columnIndex) {// the data type of each columnreturn String.class;}@Overridepublic boolean isCellEditable(int rowIndex, int columnIndex) {return true;}@Overridepublic Object getValueAt(int rowIndex, int columnIndex) {// get the data value at a particular cellreturn curriculum[rowIndex][columnIndex];}@Overridepublic void setValueAt(Object aValue, int rowIndex, int columnIndex) {// set the data value at a particular cellcurriculum[rowIndex][columnIndex] = (String) aValue;}@Overridepublic void addTableModelListener(TableModelListener l) {// TODO Auto-generated method stub}@Overridepublic void removeTableModelListener(TableModelListener l) {// TODO Auto-generated method stub}
}