所以這是我工作的代碼。它只是一個練習,這是一個困擾了我一段時間的問題。問題是,我試圖將第二個類中傳入的參數(UDPServer服務器)應用於該類的全局變量(myserv)我可以在運行方法中使用它。問題是,它說,服務器不爲NULL(這是確定它的工作原理),但myserv是NULL,它難道不改變...它可能是一些愚蠢的錯誤,但我似乎無法找到它。的Java不會改變一個變量
package Server;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
public class UDPServer{
JFrame frame;
JPanel panel;
JButton button1,button2;
JTextArea area;
JScrollPane pane;
StartThread thread1;
UDPServer u;
public static void main(String[] args) {
UDPServer u = new UDPServer();
}
public UDPServer(){
frame = new JFrame("Text Server");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setUndecorated(true);
frame.getRootPane()
.setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
panel = new JPanel();
panel.setLayout(null);
area = new JTextArea();
area.setEditable(false);
button1 = new JButton("Start");
button1.setBounds(210, 10, 75, 40);
button1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent ae){
thread1 = new StartThread(u);
}
});
panel.add(button1);
button2 = new JButton("Stop");
button2.setBounds(300, 10, 75, 40);
button2.addActionListener(new ActionListener(){
public void actionPerformed (ActionEvent ae){
thread1.thread.interrupted();
thread1.socket.close();
area.append("Server is stopped\n");
button1.setEnabled(true);
button2.setEnabled(false);
}
});
button2.setEnabled(false);
panel.add(button2);
pane = new JScrollPane(area);
pane.setBounds(10, 60, 365, 250);
panel.add(pane);
frame.add(panel);
frame.setSize(400, 400);
frame.setVisible(true);
}
}
這是第一類,那是第二個。
package Server;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.UnknownHostException;
public class StartThread implements Runnable{
DatagramSocket socket;
private final UDPServer myserv;
Thread thread;
StartThread(UDPServer server){
myserv = server;
thread = new Thread(this);
thread.start();
myserv.button1.setEnabled(false);
myserv.button2.setEnabled(true);
}
public void run(){
try{
byte[] buffer = new byte[1024];
int port = 8080;
try{
socket = new DatagramSocket(port);
while(true){
try{
myserv.area.append("Server is started\n");
//Receive request from client
DatagramPacket packet =
new DatagramPacket(buffer, buffer.length);
socket.receive(packet);
InetAddress client = packet.getAddress();
int client_port = packet.getPort();
myserv.area.append(" Received "
+new String(buffer)+" from "+client);
}
catch(UnknownHostException ue){}
}
}
catch(java.net.BindException b){}
}
catch (IOException e){
System.err.println(e);
}
}
}
這段代碼太相互依賴;你在創建'UDPServer'的時候創建了'StartThread',並且每個都依賴於另一個。使代碼更少耦合。 –