java - StringTokenizer 的问题

Question

我收到以下错误消息，但我似乎无法找出问题所在。非常感谢任何帮助。错误消息如下:-

BaseStaInstance.java:68:找不到符号

符号:构造函数 StringTokenizer(java.lang.Object,java.lang.String)

位置:类 java.util.StringTokenizer st = new StringTokenizer(buf,",");

                                  ^

在这里，BaseStaInstance 是我的主要公共(public)类。

实现这个StringTokenizer的类如下:-

类 ServerConnect 扩展了线程 {

Socket skt;
int iProcessId, iInProcessId;
int iOwnTimeStamp, iInTimeStamp;
ServerConnect scnt = null;

ObjectOutputStream myOutput;
ObjectInputStream myInput;

ServerConnect(){}
ServerConnect(Socket connection, int iProcessNo) {
    this.skt = connection;
    this.iProcessId = iProcessNo;
}

public void run() {
    try {

        //initialize the object "scnt" using the parameterized constructor
        ServerConnect scnt = new ServerConnect(skt, iProcessId);
        myInput = new ObjectInputStream(skt.getInputStream());

        while(true) {
            try{
                iOwnTimeStamp = Global.iTimeStamp;

                Object buf = myInput.readObject();

                //if we got input, print it out and write a message back to the remote client...
                if(buf != null){
                    scnt.replyChoice(buf);
                }
            }catch(ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    } catch(IOException e) {
        e.printStackTrace();
    }
}

void replyChoice(Object buf){       
    try{
        String sDeferReply = "";
        myOutput = new ObjectOutputStream(skt.getOutputStream());

        //the place where the basestation reads the request from the other basestation
        System.out.println("Server read:[ "+buf+" ]");

        //extract out the process id and the timestamp from the incoming request
        buf = buf.toString();

        ***StringTokenizer st = new StringTokenizer(buf,",");***

        //skip the word request
        st.nextToken();
        iInProcessId = Integer.parseInt(st.nextToken());
        iInTimeStamp = Integer.parseInt(st.nextToken());

        //check request is made
        //there is a possibility of entering the else loop only on the very first iteration
        //the control flows into the if loop even if one request has been made
        if(iOwnTimeStamp != 0){
            //if the incoming request has a larger timestamp (logical clock value, process id) than the current process, we defer the reply
            if(iOwnTimeStamp < iInTimeStamp || iProcessId < iInProcessId){
                sDeferReply="iInTimeStamp"+","+"iInProcessId";
                Global.v.addElement(new String(sDeferReply));
            }
            //incoming request has a smaller timestamp than the basestation request itself
            else{
                myOutput.writeObject("Reply");
                myOutput.flush();
            }
        }
        //if the current process is in the critical section then we defer replies
        else if(Global.iCriticalSection==1){
            sDeferReply="iInTimeStamp"+","+"iInProcessId";
            Global.v.addElement(new String(sDeferReply));
        }
        //start of execution of the thread, there is a possibility that the basestation hasn't issued a request
        else{
            myOutput.writeObject("Reply");
            myOutput.flush();   
        }
    }catch(IOException e){
        e.printStackTrace();
    }
}

}

实现 StringTokenizer 函数的部分有 *** 包围。

预先感谢任何能够帮助我的人。

Answer 1

尝试

StringTokenizer st = new StringTokenizer((String) buf,",");

您收到该错误的原因是 buf ，同时引用 String此时，仍然是 Object 类型.

---

作为附加提示，您确实应该努力尝试理解编译器给出的错误消息。请看以下内容:

cannot find symbol constructor StringTokenizer(java.lang.Object,java.lang.String)
location: class java.util.StringTokenizer st = new StringTokenizer(buf,",");

编译器错误消息并不总是有意义，但是这已经是最好的了。它告诉你:

• 它找到了正确的类型，java.util.StringTokenizer ，所以它不是 import或名称模糊问题等。
• 它告诉您无法找到具有给定签名的特定方法。事实上，对 API 的快速检查证实了 StringTokenizer没有采用 (java.lang.Object, java.lang.String) 的构造函数.
• 它告诉您程序中的确切代码行尝试调用这个不存在的方法。 确实，你的第一个参数的类型是 java.lang.Object ，第二个参数的类型是 java.lang.String !!!

这就是我能够快速查明源代码中的问题并提出快速修复建议的方式。

能够处理编译器给出的错误消息是您必须培养的一项基本技能，因此我希望这对您来说是一次教育经历。