Java語言支持UDP和TCP兩種網絡通信協議，本文將介紹一些Java中的UDP和TCP案例：

以下是一個基于UDP協議的案例，用于發送和接收數據包：

DatagramSocket socket = new DatagramSocket();
String message = "Hello UDP";
byte[] buf = message.getBytes();
InetAddress addr = InetAddress.getByName("127.0.0.1");
DatagramPacket packet = new DatagramPacket(buf, buf.length, addr, 8888);
socket.send(packet);
byte[] receiveBuf = new byte[1024];
packet = new DatagramPacket(receiveBuf , receiveBuf.length);
socket.receive(packet);
String receiveMessage = new String(packet.getData(),0,packet.getLength());
System.out.println("Received message：" + receiveMessage);
socket.close();

以下是基于TCP協議的案例，用于建立服務端和客戶端之間的連接：

// 服務端
ServerSocket serverSocket = new ServerSocket(8888);
Socket socket = serverSocket.accept();
DataInputStream dis = new DataInputStream(socket.getInputStream());
String message = dis.readUTF();
System.out.println("Received message：" + message);
DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
dos.writeUTF("Hello TCP");
dos.flush();
dis.close();
dos.close();
socket.close();
serverSocket.close();
// 客戶端
Socket socket = new Socket("127.0.0.1", 8888);
DataInputStream dis = new DataInputStream(socket.getInputStream());
DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
dos.writeUTF("TCP server, I'm the client");
dos.flush();
String message = dis.readUTF();
System.out.println("Received message：" + message);
dis.close();
dos.close();
socket.close();

以上是一些基于UDP和TCP協議的案例，Java語言具有強大的網絡通信功能，可以方便地實現各種網絡應用程序。