如何从另一个方法获取变量的值而不将其作为参数传递？

Question

我正在尝试创建一个聊天应用程序（是的，我知道，不是很有创意）并且我想将套接字变量的值传输到其他方法中。

但是我很困惑我该怎么办？

我已经尝试过将其作为参数传递，但由于某种原因不起作用，还尝试在方法之外声明变量，这也不起作用。

    public void DeclaringVariables() throws IOException{

        InetAddress group = InetAddress.getByName("239.255.255.255"); 
        int port = 1201; 
        Scanner sc = new Scanner(System.in); 
        System.out.print("Enter your name: "); 
        name = sc.nextLine(); 
        MulticastSocket socket = new MulticastSocket(port); 

        // Since we are deploying 
        socket.setTimeToLive(0); 
        //this on localhost only (For a subnet set it as 1) 

        socket.joinGroup(group); 
        Thread t = new Thread(new
        ReadThread(socket,group,port)); 

            // Spawn a thread for reading messages 
        t.start();

    }          

/**
 *
 */
public void SendButton() {

    try {

        while(true) {

                String message; 
                message = sc.nextLine(); 
                if(message.equalsIgnoreCase(GroupChat.TERMINATE)) 
                { 
                    finished = true; 
                    socket.leaveGroup(group); 
                    socket.close(); 
                    break; 
                } 
                message = name + ": " + message; 
                byte[] buffer = message.getBytes(); 
                DatagramPacket datagram = new
                DatagramPacket(buffer,buffer.length,group,port); 
                socket.send(datagram); 

    }
    } 

    catch (IOException ex) {
        Logger.getLogger(ChatGUI.class.getName()).log(Level.SEVERE, null, ex);
    }
    }

Answer 1

如果您在多个方法中需要socket，请考虑将其声明为类属性，而不是局部变量。这样，您可以在类构造函数中实例化它并通过类中的所有方法访问它。像这样：

public class MyClass {

    // declare it here
    private MulticastSocket socket;

    public MyClass() {
        // instantiate it here
        socket = new MulticastSocket(1201); 
    }

    public void myMethod() {
        // now you can use it everywhere!
        socket.someMethod();
    }

}