NoSuchElementException: строки не найдено?

Question

Я работаю над созданием PalindromeServer в java, однако я продолжаю получать ошибку, найденную в строке, которая, кажется, исходит из моего PrintWriter, но я не могу понять, почему. Может ли кто-нибудь объяснить, что вызывает ошибку, не найденную в строке?

мой код

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


public class PalindromeServer { 

public static void main(String[] args){ 
    try{ 
    int port = 5150; 
    ServerSocket ssocket = new ServerSocket(port); 


    Socket client = ssocket.accept(); 

    OutputStream outStream = client.getOutputStream(); 
    Scanner scan = new Scanner(client.getInputStream()); 
    PrintWriter writer = new PrintWriter(outStream, true); 

    while(scan.hasNextLine()){ 
     String in = scan.nextLine(); 
     String out = ""; 
     if(in.equals("SHUT DOWN")){ 
      ssocket.close(); 
     } 
     in.replaceAll("\\s+",""); 
     int length = in.length(); 

      for (int i = length - 1 ; i >= 0 ; i--){ 
      out = out + in.charAt(i); 
      } 
      in.toLowerCase(); 
      out.toLowerCase(); 

      if(in.equals(out)){ 
       writer.print("YES"); 
       client.close(); 
      } 
      else{ 
       writer.print("NO"); 
       client.close(); 
      } 
    } 

}catch (IOException e) {} 

} 
} 

Junit Тесты

import org.junit.runners.MethodSorters; 

import static org.junit.Assert.*; 

import java.io.IOException; 
import java.io.PrintWriter; 
import java.net.Socket; 
import java.util.Scanner; 

import org.junit.Before; 
import org.junit.BeforeClass; 
import org.junit.FixMethodOrder; 
import org.junit.Test; 

@FixMethodOrder(MethodSorters.NAME_ASCENDING) 
public class PalindromeServerTest { 
@BeforeClass 
public static void startServer() { 
    // run server 
    Thread thread = new Thread(new Runnable() { 
     @Override 
     public void run() { 
      PalindromeServer.main(null); 
     } 
    }); 
    thread.start(); 
} 
@Before 
public void waitTwoSecondsBetweenTests() { 
    try { 
     Thread.sleep(2000); 
    } 
    catch (InterruptedException e) { 
     e.printStackTrace(); 
    } 
} 

@Test(timeout=3000) 
public void testServerWithNonPalindrome() { 
    try { 
     // run client 
     Socket  socket = new Socket("localhost", 5150); 
     Scanner  scanner = new Scanner (socket.getInputStream()); 
     PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); 

     writer.println("Not in Here"); 

     String result = scanner.nextLine(); 
     assertEquals("Incorrect result", "NO", result); 

     socket.close(); 
    } 
    catch (IOException e) { 
     e.printStackTrace(); 
     fail("Error opening client socket"); 
    } 
} 

@Test(timeout=3000) 
public void testServerWith1LetterPalindrome() { 
    try { 
     // run client 
     Socket  socket = new Socket("localhost", 5150); 
     Scanner  scanner = new Scanner (socket.getInputStream()); 
     PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); 

     writer.println("Z"); 

     String result = scanner.nextLine(); 
     assertEquals("Incorrect result", "YES", result); 

     socket.close(); 
    } 
    catch (IOException e) { 
     e.printStackTrace(); 
     fail("Error opening client socket"); 
    } 
} 

@Test(timeout=3000) 
public void testServerWithPalindrome() throws IOException { 
    try { 
     // run client 
     Socket  socket = new Socket("localhost", 5150); 
     Scanner  scanner = new Scanner (socket.getInputStream()); 
     PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); 

     writer.println("Kayak"); 

     String result = scanner.nextLine(); 
     assertEquals("Incorrect result", "YES", result); 

     socket.close(); 
    } 
    catch (IOException e) { 
     e.printStackTrace(); 
     fail("Error opening client socket"); 
    } 
} 

@Test(timeout=3000) 
public void testServerWithPerfectPalindrome() throws IOException { 
    try { 
     // run client 
     Socket  socket = new Socket("localhost", 5150); 
     Scanner  scanner = new Scanner (socket.getInputStream()); 
     PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); 

     writer.println("Able was I ere I saw Elba"); 

     String result = scanner.nextLine(); 
     assertEquals("Incorrect result", "YES", result); 

     socket.close(); 
    } 
    catch (IOException e) { 
     e.printStackTrace(); 
     fail("Error opening client socket"); 
    } 
} 

@Test(timeout=3000) 
public void testServerWithCapitalizedPalindrome() throws IOException { 
    try { 
     // run client 
     Socket  socket = new Socket("localhost", 5150); 
     Scanner  scanner = new Scanner (socket.getInputStream()); 
     PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); 

     writer.println("I prefer PI"); 

     String result = scanner.nextLine(); 
     assertEquals("Incorrect result", "YES", result); 

     socket.close(); 
    } 
    catch (IOException e) { 
     e.printStackTrace(); 
     fail("Error opening client socket"); 
    } 
} 

@Test(timeout=3000) 
public void testServerWithNonSense() throws IOException { 
    try { 
     // run client 
     Socket  socket = new Socket("localhost", 5150); 
     Scanner  scanner = new Scanner (socket.getInputStream()); 
     PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); 

     writer.println("I want my mojo back!"); 

     String result = scanner.nextLine(); 
     assertEquals("Incorrect result", "NO", result); 

     socket.close(); 
    } 
    catch (IOException e) { 
     e.printStackTrace(); 
     fail("Error opening client socket"); 
    } 
} 

@Test(expected = IOException.class) 
public void test_RunsLast_ServerShutsDown() throws IOException { 
    try { 
     // running client #1...shuts down server 
     Socket  socket = new Socket("localhost", 5150); 
     PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); 

     writer.println("SHUT DOWN"); 

     socket.close(); 
    } 
    catch (IOException e) { 
     e.printStackTrace(); 
     fail("Error opening client socket"); 
    } 
    waitTwoSecondsBetweenTests(); 

    // running client #2...should throw exception (server should have stopped) 
    new Socket("localhost", 5150); 
    fail("Socket should not connect after server was shut down"); 
} 

Error

java.util.NoSuchElementException: No line found 
at java.util.Scanner.nextLine(Unknown Source) 
at PalindromeServerTest.testServerWith1LetterPalindrome(PalindromeServerTest.java:69) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
at java.lang.reflect.Method.invoke(Unknown Source) 
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47) 
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) 
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44) 
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) 
at org.junit.internal.runners.statements.FailOnTimeout$StatementThread.run(FailOnTimeout.java:74) 

Answer 1

scan имеет "ни одна строка не найдена" (NoSuchElementException) потому, что вы закрываете свой client. Подождите, чтобы закрыть своего клиента после завершения цикла.

while(scan.hasNextLine()) { 
    ... 

    if(in.equals(out)){ 
     writer.print("YES"); 
    } 
    else{ 
     writer.print("NO"); 
    } 

    ... 
} 

client.close();