线程“main”java.lang.NumberFormatException中的异常：对于输入字符串：“100”[重复]

Question

当我收到一个从单独的客户端程序转换为字符串的整数（事务 ID）时，我的 Java UDP 服务器程序的 sn-p 出现错误：

客户：

// Sending transaction ID to server
sendData = String.valueOf(transID).getBytes();
sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, sportno);
clientSocket.send(sendPacket);

服务器：

// Receive client's transaction ID
receiveData = new byte[1024]; // 1024 byte limit when receiving
receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket); // Server receives packet "100" from client
String clientMsg = new String(receivePacket.getData()); // String to hold received packet
int transID = Integer.valueOf(clientMsg); // Convert clientMsg to integer
System.out.println("Client has sent: " + transID); // Printing integer before iteration

虽然客户端发送数据包很好，但在字符串到整数的转换过程中我收到了这个错误：

Exception in thread "main" java.lang.NumberFormatException: For input string: "100"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.valueOf(Integer.java:766)
at server.main(server.java:46)

我还使用了 Integer.parseInt(clientMsg) 并获得了类似的结果。但是，只要我不尝试将其转换为整数，程序就可以将数据包打印为字符串值。

此外，虽然它在终端中显示了这一点，但当我将此错误消息复制并粘贴到这篇文章中时，“100”后面跟着大量“”，我假设其余的都是空的来自 receiveData 变量的字节。

这些空值会是我的程序失败的原因吗？如果不是，程序失败的其他原因是什么？另外，有没有办法将事务ID整数发送到服务器而不先将其转换为字符串以防止出现此错误？

Answer 1

String clientMsg = new String(receivePacket.getData()); // String to hold received packet

问题就在这里。通过忽略传入数据报的实际长度，您正在附加垃圾。应该是：

String clientMsg = new String(receivePacket.getData(), receivePacket.getOffset(), receivePacket.getLength()); // String to hold received packet

Answer 2

试试希望这行得通

String receivedMsg = new String(receivePacket.getData(), receivePacket.getOffset(), receivePacket.getLength());