我是编程新手,我需要帮助解决这个小障碍。我正在制作一个简单的聊天程序,带有服务器和聊天客户端。因此,我的客户端启动并创建了一个网络连接,其中包括一个PrintWriter
发送到我的服务器的网络连接。然后,在另一个类(我的ActionListener
)中,当我调用 writer 变量时,它以 void 结束NullPointerException
。
因此,我尝试在每次 ActionListener 运行时调用 setupnetworking,但它们最终会连接到许多连接,并且我的消息不止一次打印出来。我可以在我的方法中保留 setupnetworking ,并为我的班级main()
保留变量值吗?如果我感到困惑,我很抱歉,所以请查看我的代码并告诉我您的想法。PrintWriter
ActionListener
这是整个程序...
import java.util.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
import java.io.*;
import java.net.*;
public class SimpleChatClient {
BufferedReader reader;
PrintWriter writer;
Socket sock;
JTextArea chatbox = new JTextArea(10,20);
JTextField entertext = new JTextField(20);
JButton sendchat = new JButton("send");
public void go(){
setUpNetworking();
Thread readerThread1 = new Thread(new IncomingReader());
readerThread1.start();
//big probelm. to many setUpNetworkings!!!!!!!!
}
public class SendButtonListener implements ActionListener{
public void actionPerformed (ActionEvent ev){
try {
writer.println(entertext.getText());
writer.flush();
System.out.println("chat flush");
}
catch (Exception ex) {
ex.printStackTrace();
System.out.println("action fail");
}
entertext.setText("");
entertext.requestFocus();
}
}
public void setUpNetworking() {
try {
sock = new Socket("192.168.0.11", 65534);
InputStreamReader streamReader =
new InputStreamReader(sock.getInputStream());
reader = new BufferedReader(streamReader);
writer = new PrintWriter(sock.getOutputStream(), true);
System.out.println("network established. Beginning mainstream feed.");
}
catch (IOException ex) {
ex.printStackTrace();
System.out.println("setup fail");
}
}
public class IncomingReader implements Runnable {
public void run() {
String message;
try {
while ((message = reader.readLine()) != null) {
System.out.println("read " + message);
chatbox.append(message + "\n");
chatbox.append("\n");
}
}catch (Exception ex) {
ex.printStackTrace();
System.out.println("run fail");
}
}
}
}
Ps 我也有一个 GUI 程序。这只是建立连接。