Bill's changes and formatting

network/MultiSimpleClient.java

@@ -2,75 +2,50 @@
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
-// Testing MultiSimpleServer with multiple clients
+// Testing MultiSimpleServer with multiple clients.
 // {ValidateByHand}
 import java.net.*;
 import java.io.*;
 import onjava.*;
 
-class SimpleClientThread extends Thread {
-  private Socket socket;
-  private BufferedReader in;
-  private PrintWriter out;
+class SimpleClientThread implements Runnable {
+  private InetAddress address;
   private static int counter = 0;
   private int id = counter++;
   private static int threadcount = 0;
   public static int threadCount() {
     return threadcount;
   }
-  public SimpleClientThread(InetAddress addr) {
+  public SimpleClientThread(InetAddress address) {
     System.out.println("Making client " + id);
+    this.address = address;
     threadcount++;
-    try {
-      socket =
-        new Socket(addr, MultiSimpleServer.PORT);
-    } catch(IOException e) {
-      // If the creation of the socket fails,
-      // nothing needs cleanup.
-    }
-    try {
-      in =
-        new BufferedReader(
-          new InputStreamReader(
-            socket.getInputStream()));
-      // Enable auto-flush:
-      out =
-        new PrintWriter(
-          new BufferedWriter(
-            new OutputStreamWriter(
-              socket.getOutputStream())), true);
-      start();
-    } catch(IOException e) {
-      // The socket should be closed on any
-      // failures other than the socket
-      // constructor:
-      try {
-        socket.close();
-      } catch(IOException e2) {
-        throw new RuntimeException(e2);
-      }
-    }
-    // Otherwise the socket will be closed by
-    // the run() method of the thread.
   }
   @Override
   public void run() {
-    try {
-      for(int i = 0; i < 25; i++) {
+    try (
+      Socket socket =
+        new Socket(address, MultiSimpleServer.PORT);
+      BufferedReader in =
+        new BufferedReader(
+          new InputStreamReader(
+            socket.getInputStream()));
+      PrintWriter out =
+        new PrintWriter(
+          new BufferedWriter(
+            new OutputStreamWriter(
+              // Enable auto-flush:
+              socket.getOutputStream())), true)
+    ) {
+      for (int i = 0; i < 25; i++) {
         out.println("Client " + id + ": " + i);
         String str = in.readLine();
         System.out.println(str);
       }
       out.println("END");
-    } catch(IOException e) {
-      throw new RuntimeException(e);
+    } catch (IOException ex) {
+        throw new RuntimeException(ex);
     } finally {
-      // Always close it:
-      try {
-        socket.close();
-      } catch(IOException e) {
-        throw new RuntimeException(e);
-      }
       threadcount--; // Ending this thread
     }
   }
@@ -82,10 +57,10 @@ public class MultiSimpleClient {
   main(String[] args) throws IOException,
   InterruptedException {
     new TimedAbort(5); // Terminate after 5 seconds
-    InetAddress addr = InetAddress.getByName(null);
+    InetAddress address = InetAddress.getByName(null);
     while(true) {
       if(SimpleClientThread.threadCount() < MAX_THREADS)
-        new SimpleClientThread(addr);
+        new SimpleClientThread(address);
       Thread.sleep(100);
     }
   }

network/MultiSimpleServer.java

@@ -2,52 +2,42 @@
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
-// Uses threads to handle any number of clients
+// Uses threads to handle any number of clients.
 // {ValidateByHand}
 import java.io.*;
 import java.net.*;
 import onjava.*;
 
-class ServeOneSimple extends Thread {
-  private Socket socket;
-  private BufferedReader in;
-  private PrintWriter out;
-  public ServeOneSimple(Socket s)
-      throws IOException {
-    socket = s;
-    in =
-      new BufferedReader(
-        new InputStreamReader(
-          socket.getInputStream()));
-    // Enable auto-flush:
-    out =
-      new PrintWriter(
-        new BufferedWriter(
-          new OutputStreamWriter(
-            socket.getOutputStream())), true);
-    // If any of the above calls throw an exception,
-    // the caller is responsible for closing the
-    // socket. Otherwise the thread closes it.
-    start(); // Calls run()
+class ServeOneSimple implements Runnable {
+  private ServerSocket ss;
+  public
+  ServeOneSimple(ServerSocket ss) throws IOException {
+    this.ss = ss;
   }
   @Override
   public void run() {
-    try {
+    try (
+      Socket socket = ss.accept();
+      BufferedReader in =
+        new BufferedReader(
+          new InputStreamReader(
+            socket.getInputStream()));
+      PrintWriter out =
+        new PrintWriter(
+          new BufferedWriter(
+            new OutputStreamWriter(
+              // Enable auto-flush:
+              socket.getOutputStream())), true)
+    ) {
       while (true) {
         String str = in.readLine();
         if(str.equals("END")) break;
         System.out.println("Echoing: " + str);
         out.println(str);
       }
-      System.out.println("closing...");
+      System.out.println("closing socket...");
     } catch (IOException e) {
       throw new RuntimeException(e);
-    } finally {
-      try {
-        socket.close();
-      } catch(IOException e) {
-        throw new RuntimeException(e);
-      }
     }
   }
 }
@@ -57,22 +47,12 @@ public class MultiSimpleServer {
   public static void
   main(String[] args) throws IOException {
     new TimedAbort(5); // Terminate after 5 seconds
-    ServerSocket s = new ServerSocket(PORT);
     System.out.println("Server Started");
-    try {
+    try (ServerSocket ss = new ServerSocket(PORT)){
+      // Block until a connection occurs:
       while(true) {
-        // Blocks until a connection occurs:
-        Socket socket = s.accept();
-        try {
-          new ServeOneSimple(socket);
-        } catch(IOException e) {
-          // If it fails, close the socket,
-          // otherwise the thread will close it:
-          socket.close();
-        }
+          new ServeOneSimple(ss);
       }
-    } finally {
-      s.close();
     }
   }
 }

network/SimpleClient.java

@@ -3,7 +3,7 @@
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
 // Sends lines to the server and
-// reads lines the server sends
+// reads lines the server sends.
 // {ValidateByHand}
 import java.net.*;
 import java.io.*;
@@ -16,32 +16,27 @@ public class SimpleClient {
     InetAddress addr =
       InetAddress.getLoopbackAddress();
     System.out.println("addr = " + addr);
-    Socket socket =
-      new Socket(addr, SimpleServer.PORT);
-    // Guard everything in a try-finally to make
-    // sure that the socket is closed:
-    try {
-      System.out.println("socket = " + socket);
+    // TWR will sure that the socket is closed:
+    try (
+      Socket socket = new Socket(addr, SimpleServer.PORT);
       BufferedReader in =
         new BufferedReader(
           new InputStreamReader(
             socket.getInputStream()));
-      // Output is automatically flushed
-      // by PrintWriter:
       PrintWriter out =
         new PrintWriter(
           new BufferedWriter(
             new OutputStreamWriter(
-              socket.getOutputStream())),true);
+              // Enable auto-flush:
+              socket.getOutputStream())), true);
+    ) {
+      System.out.println("socket: " + socket);
       for(int i = 0; i < 10; i ++) {
         out.println("hello " + i);
         String str = in.readLine();
         System.out.println(str);
       }
       out.println("END");
-    } finally {
-      System.out.println("closing...");
-      socket.close();
     }
   }
 }

network/SimpleServer.java

@@ -2,7 +2,7 @@
 // (c)2016 MindView LLC: see Copyright.txt
 // We make no guarantees that this code is fit for any purpose.
 // Visit http://mindviewinc.com/Books/OnJava/ for more book information.
-// Echoes what the client sends
+// Echoes what the client sends.
 // {ValidateByHand}
 import java.io.*;
 import java.net.*;
@@ -12,38 +12,28 @@ public class SimpleServer {
   public static final int PORT = 8080;
   public static void
   main(String[] args) throws IOException {
-    ServerSocket s = new ServerSocket(PORT);
-    System.out.println("Started: " + s);
-    try {
+    try (
+      ServerSocket s = new ServerSocket(PORT);
       // Blocks until a connection occurs:
       Socket socket = s.accept();
-      try {
-        System.out.println(
-          "Connection accepted: "+ socket);
-        BufferedReader in =
-          new BufferedReader(
-            new InputStreamReader(
-              socket.getInputStream()));
-        // Output is automatically flushed
-        // by PrintWriter:
-        PrintWriter out =
-          new PrintWriter(
-            new BufferedWriter(
-              new OutputStreamWriter(
-                socket.getOutputStream())), true);
-        while (true) {
-          String str = in.readLine();
-          if(str.equals("END")) break;
-          System.out.println("Echoing: " + str);
-          out.println(str);
-        }
-      // Always close the two sockets...
-      } finally {
-        System.out.println("closing...");
-        socket.close();
+      BufferedReader in =
+      new BufferedReader(
+        new InputStreamReader(
+          socket.getInputStream()));
+      PrintWriter out =
+        new PrintWriter(
+          new BufferedWriter(
+            new OutputStreamWriter(
+              // Enable auto-flush:
+              socket.getOutputStream())), true)
+    ) {
+      System.out.println("Connection: " + socket);
+      while (true) {
+        String str = in.readLine();
+        if(str.equals("END")) break;
+        System.out.println("Echoing: " + str);
+        out.println(str);
       }
-    } finally {
-      s.close();
     }
   }
 }