From e638d8d662f5bb49854897dc8bf19f4fb42a6705 Mon Sep 17 00:00:00 2001
From: Christopher Bohn <bohn@unl.edu>
Date: Tue, 5 Nov 2019 11:53:15 -0600
Subject: [PATCH] Application recovers if user enters invalid port number.
---
.../edu/unl/cse/csce361/socket_chat/Chat.java | 30 ++++++++++++++-----
1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java b/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java
index 31db30f..e655ac2 100644
--- a/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java
+++ b/src/main/java/edu/unl/cse/csce361/socket_chat/Chat.java
@@ -4,6 +4,7 @@ import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
+import java.util.InputMismatchException;
import java.util.Scanner;
public class Chat {
@@ -64,8 +65,8 @@ public class Chat {
private Socket connectAsServer() throws IOException {
byte[] address = InetAddress.getLocalHost().getAddress();
System.out.println("Host address: " + address[0] + "." + address[1] + "." + address[2] + "." + address[3]);
- System.out.print("Select port number: ");
- int port = getPort();
+ String prompt = "Select port number";
+ short port = getPort(prompt);
ServerSocket serverSocket = new ServerSocket(port);
return serverSocket.accept();
}
@@ -78,15 +79,28 @@ public class Chat {
for (int i = 0; i < 4; i++) {
address[i] = Byte.parseByte(tokens[i]);
}
- System.out.print("Enter port host is opening at " +
- address[0] + "." + address[1] + "." + address[2] + "." + address[3] + ": ");
- int port = getPort();
+ String prompt = "Enter port host is opening at " +
+ address[0] + "." + address[1] + "." + address[2] + "." + address[3];
+ short port = getPort(prompt);
return new Socket(InetAddress.getByAddress(address), port);
}
- private int getPort() {
- int port = scanner.nextInt();
- scanner.nextLine();
+ private short getPort(String prompt) {
+ boolean haveGoodNumber = false;
+ short port = 0;
+ while (!haveGoodNumber) {
+ System.out.print(prompt + ": ");
+ haveGoodNumber = true;
+ try {
+ port = scanner.nextShort();
+ if (port < 0) throw new InputMismatchException("Expected non-negative value, got " + port);
+ } catch (InputMismatchException ignored) {
+ System.out.println("The port number must be a positive integer strictly less than 65536.");
+ haveGoodNumber = false;
+ } finally {
+ scanner.nextLine();
+ }
+ }
return port;
}
--
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