Further try-with-resources rewrite

Author: Bruce Eckel

network/ChatterClient.java

@@ -10,8 +10,6 @@
 import onjava.*;
 
 public class ChatterClient extends Thread {
-  // Can listen & send on the same socket:
-  private DatagramSocket s;
   private InetAddress hostAddress;
   private byte[] buf = new byte[1000];
   private DatagramPacket dp =
@@ -21,21 +19,19 @@ public class ChatterClient extends Thread {
   public ChatterClient(int identifier) {
     id = identifier;
     try {
-      // Auto-assign port number:
-      s = new DatagramSocket();
       hostAddress =
         InetAddress.getByName("localhost");
     } catch(UnknownHostException e) {
       System.err.println("Cannot find host");
       System.exit(1);
-    } catch(SocketException e) {
-      System.err.println("Can't open socket");
-      throw new RuntimeException(e);
     }
     System.out.println("ChatterClient starting");
   }
   public void sendAndEcho(String msg) {
-    try {
+    try (
+      // Auto-assign port number:
+      DatagramSocket s = new DatagramSocket();
+    ) {
       // Make and send a datagram:
       s.send(Dgram.toDatagram(
         msg, hostAddress, ChatterServer.INPORT));
@@ -48,6 +44,9 @@ public void sendAndEcho(String msg) {
         dp.getPort() + ": " +
         Dgram.toString(dp);
       System.out.println(rcvd);
+    } catch(SocketException e) {
+      System.err.println("Can't open socket");
+      throw new RuntimeException(e);
     } catch(IOException e) {
       throw new RuntimeException(e);
     }

network/ChatterServer.java

@@ -13,12 +13,12 @@ public class ChatterServer {
   private byte[] buf = new byte[1000];
   private DatagramPacket dp =
     new DatagramPacket(buf, buf.length);
-  // Can listen & send on the same socket:
-  private DatagramSocket socket;
 
   public ChatterServer() {
-    try {
-      socket = new DatagramSocket(INPORT);
+    // Can listen & send on the same socket:
+    try (
+      DatagramSocket socket = new DatagramSocket(INPORT)
+    ) {
       System.out.println("Server started");
       while(true) {
         // Block until a datagram appears:
@@ -37,9 +37,6 @@ public ChatterServer() {
             dp.getAddress(), dp.getPort());
         socket.send(echo);
       }
-    } catch(SocketException e) {
-      System.err.println("Can't open socket");
-      System.exit(1);
     } catch(IOException e) {
       System.out.println("Communication error");
       throw new RuntimeException(e);