Chapter 31 Exercise 6, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

31.6 (Display and add addresses) Develop a client/server application to view and
add addresses, as shown in Figure 31.20.

■Use the StudentAddress class defined in Listing 31.5 to hold the name,
street, city, state, and zip in an object.
■The user can use the buttons First, Next, Previous, and Last to view an
address, and the Add button to add a new address.
■Limit the concurrent connections to two clients.

Name the client Exercise31_06Client and the server Exercise31_6Server.

import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class Exercise06s {
 private ArrayList<Address> addresses = new ArrayList<>();
 int current = 0;
 int activeClients = 0;
 
 public Exercise06s() {  
  ServerSocket serverSocket = null;
  try {
   serverSocket = new ServerSocket(8000);
   while (true) {
    if(activeClients >= 2) {
     try {
      Thread.sleep(10);
     } catch (InterruptedException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
     }
    } else {
     Socket socket = serverSocket.accept();  
     HandleClient task = new HandleClient(socket);
     activeClients++;
     new Thread(task).start();
    }
   }
  } catch (IOException ex) {
   System.err.println(ex);
  }
 
 }

 public static void main(String[] args) {
  new Exercise06s();
 }
 
 class HandleClient implements Runnable {
  private Socket socket;
  
  public HandleClient(Socket socket) {
   this.socket = socket;
  }
  
  @Override
  public void run() {
   Scanner inputFromClient;
   PrintWriter outputToClient;
   try {
    inputFromClient = new Scanner(socket.getInputStream());
    outputToClient = new PrintWriter(socket.getOutputStream());
    
    while (true) {
     int command = Integer.parseInt(inputFromClient.next());
     switch (command) {
     case 1:
      Address address = new Address(inputFromClient.next(), inputFromClient.next(), inputFromClient.next(), inputFromClient.next(), inputFromClient.next());
      addresses.add(address);
      current = 0;
      break;
     case 2:
      if(!addresses.isEmpty()) {
       outputToClient.write("1 ");
       outputToClient.flush();
       addresses.get(0).send(outputToClient);
       current = 0;       
      } else {
       outputToClient.write("0 ");
       outputToClient.flush();
      }
      break;
     case 3:
      if(!addresses.isEmpty()) {
       outputToClient.write("1 ");
       outputToClient.flush();
       if(current < addresses.size() - 1) {
        current++;
       }
       addresses.get(current).send(outputToClient);
      } else {
       outputToClient.write("0 ");
       outputToClient.flush();
      }
      break;
     case 4:
      if(!addresses.isEmpty()) {
       outputToClient.write("1 ");
       outputToClient.flush();
       if(current > 0) {
        current--;
       }
       addresses.get(current).send(outputToClient);
      } else {
       outputToClient.write("0 ");
       outputToClient.flush();
      }      
      break;
     case 5:
      if(!addresses.isEmpty()) {
       outputToClient.write("1 ");
       outputToClient.flush();
       addresses.get(addresses.size() - 1).send(outputToClient);
       current = addresses.size() - 1;       
      } else {
       outputToClient.write("0 ");
       outputToClient.flush();
      }
      break;
     default:
      break;
     }
    }
   } catch (IOException e) {
    e.printStackTrace();
   } catch (NoSuchElementException e) {
    activeClients--;
   }
  }
  
 }
 
 static class Address {
  String name;
  String street;
  String city;
  String state;
  String zip;
  
  public void send(PrintWriter outputToClient) {
   outputToClient.write(name + " ");
   outputToClient.write(street + " ");
   outputToClient.write(city + " ");
   outputToClient.write(state + " ");
   outputToClient.write(zip + " ");
   outputToClient.flush();
  }
  
  public Address(String name, String street, String city, String state, String zip) {
   this.name = name;
   this.street = street;
   this.city = city;
   this.state = state;
   this.zip = zip;
  }
  public String getName() {
   return name;
  }
  public void setName(String name) {
   this.name = name;
  }
  public String getStreet() {
   return street;
  }
  public void setStreet(String street) {
   this.street = street;
  }
  public String getCity() {
   return city;
  }
  public void setCity(String city) {
   this.city = city;
  }
  public String getState() {
   return state;
  }
  public void setState(String state) {
   this.state = state;
  }
  public String getZip() {
   return zip;
  }
  public void setZip(String zip) {
   this.zip = zip;
  }
  
  
 }

}

import javax.swing.*;
import javax.swing.border.EmptyBorder;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class Exercise06c extends JApplet {
 private static final long serialVersionUID = 1L;
 private JTextField jtfName = new JTextField();
 private JTextField jtfStreet = new JTextField();
 private JTextField jtfCity = new JTextField();
 private JTextField jtfState = new JTextField();
 private JTextField jtfZip = new JTextField();
 private JLabel jlblName = new JLabel("Name");
 private JLabel jlblStreet = new JLabel("Street");
 private JLabel jlblCity = new JLabel("City");
 private JLabel jlblState = new JLabel("State");
 private JLabel jlblZip = new JLabel("Zip");
 private JButton jbtnAdd = new JButton("Add");
 private JButton jbtnFirst = new JButton("First");
 private JButton jbtnNext = new JButton("Next");
 private JButton jbtnPrevious = new JButton("Previous");
 private JButton jbtnLast = new JButton("Last");
 private Scanner fromServer;
 private PrintWriter toServer;
 
 public void readAddress() {
  String isAvaliable = fromServer.next();
  if(isAvaliable.equals("1")) {
   jtfName.setText(fromServer.next());
   jtfStreet.setText(fromServer.next());
   jtfCity.setText(fromServer.next());
   jtfState.setText(fromServer.next());
   jtfZip.setText(fromServer.next());   
  } else {
   jtfName.setText("");
   jtfStreet.setText("");
   jtfCity.setText("");
   jtfState.setText("");
   jtfZip.setText("");   
  }

 }
 
 public Exercise06c() {
  jbtnAdd.addActionListener(new ActionListener() {   
   @Override
   public void actionPerformed(ActionEvent e) {
    toServer.write("1 ");
    toServer.flush();
    Exercise06s.Address address = new Exercise06s.Address(jtfName.getText(), jtfStreet.getText(), jtfCity.getText(), jtfState.getText(), jtfZip.getText());
    address.send(toServer);
    toServer.write("5 ");
    toServer.flush();
    readAddress();
   }
  });
  jbtnFirst.addActionListener(new ActionListener() {   
   @Override
   public void actionPerformed(ActionEvent e) {
    toServer.write("2 ");
    toServer.flush();
    readAddress();
   }
  });
  jbtnNext.addActionListener(new ActionListener() {   
   @Override
   public void actionPerformed(ActionEvent e) {
    toServer.write("3 ");
    toServer.flush();
    readAddress();
   }
  });
  jbtnPrevious.addActionListener(new ActionListener() {   
   @Override
   public void actionPerformed(ActionEvent e) {
    toServer.write("4 ");
    toServer.flush();
    readAddress();
   }
  });
  jbtnLast.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent e) {
    toServer.write("5 ");
    toServer.flush();
    readAddress();
   }
  });
  
  jlblName.setHorizontalAlignment(SwingConstants.RIGHT);
  jlblStreet.setHorizontalAlignment(SwingConstants.RIGHT);
  jlblCity.setHorizontalAlignment(SwingConstants.RIGHT);
  jlblState.setHorizontalAlignment(SwingConstants.RIGHT);
  jlblZip.setHorizontalAlignment(SwingConstants.RIGHT);
  
  JPanel jPanel1 = new JPanel(new GridLayout(3, 1, 5, 5));
  jPanel1.add(jlblName);
  jPanel1.add(jlblStreet);
  jPanel1.add(jlblCity);
  
  JPanel jPanel2 = new JPanel(new GridLayout(1, 4, 5, 5));
  jPanel2.add(jlblState);
  jPanel2.add(jtfState);
  jPanel2.add(jlblZip);
  jPanel2.add(jtfZip);
  
  JPanel jPanel3 = new JPanel(new GridLayout(1, 2, 5, 5));
  jPanel3.add(jtfCity);
  jPanel3.add(jPanel2);
  
  JPanel jPanel4 = new JPanel(new GridLayout(3, 1, 5, 5));
  jPanel4.add(jtfName);
  jPanel4.add(jtfStreet);
  jPanel4.add(jPanel3);
  
  JPanel jPanel5 = new JPanel(new BorderLayout(5,  5));
  jPanel5.add(jPanel1, BorderLayout.WEST);
  jPanel5.add(jPanel4, BorderLayout.CENTER);
  
  JPanel jPanel6 = new JPanel(new FlowLayout(FlowLayout.CENTER));
  jPanel6.add(jbtnAdd);
  jPanel6.add(jbtnFirst);
  jPanel6.add(jbtnNext);
  jPanel6.add(jbtnPrevious);
  jPanel6.add(jbtnLast);
  
  JPanel jPanel7 = new JPanel(new BorderLayout(10, 10));
  jPanel7.setBorder(new EmptyBorder(10, 10, 10, 10));
  jPanel7.add(jPanel5, BorderLayout.CENTER);
  jPanel7.add(jPanel6, BorderLayout.SOUTH);
  add(jPanel7);
  
  Socket socket;
  try {
   socket = new Socket("localhost", 8000);
   fromServer = new Scanner(socket.getInputStream());
   toServer = new PrintWriter(socket.getOutputStream());
   toServer.write("2 ");
   toServer.flush();
   readAddress();
  } catch (IOException ex) {
   ex.printStackTrace();
  }
 }
 
 

 public static void main(String[] args) {
  JFrame frame = new JFrame("Exercise06c");
  Exercise06c applet = new Exercise06c();
  frame.add(applet);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setSize(600, 180);
  frame.setMinimumSize(new Dimension(frame.getWidth(), frame.getHeight()));
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
 }

}