java StringTokenizer NoSuchElementExecption错误

Question

我得到了一个NoTouchElementException，现在调试它时，我注意到Car和Carmap被正确创建，并且值被正确存储，所以我不确定ST没有看到下一个令牌？或者当is发现不再有代币时它是否停止

感谢所有人的投入

    Carmap = new HashMap<String,Car>();
    //Change file path accordingly
    File f = new File("C:\\XXX\\XXX\\XXX\\CarFaxDB.txt");
    //Check to see if file exists, else create file
    if (f.exists()){
        String data[] = readFile(f);
        for (int i =0; i<data.length; i++){

            if (data[i] != null){
                if (i>0){
                    String line = data[i];
                    StringTokenizer st = new StringTokenizer(line,",");
                    String VIN = st.nextToken();
                    String carMake = st.nextToken();
                    String carModel = st.nextToken();
                    int carYear = Integer.parseInt(st.nextToken());
                    data[i]= line;
                    Car car = new Car(VIN, carMake, carModel, carYear);
                    Carmap.put(car.getVIN(), car);
                }
            }
        }

    }

Answer 1

出现错误是因为您试图期望一个nextToken()，但标记器没有更多的标记

在执行^{之前，您应该检查是否有更多令牌。您可以使用hasMoreTokens()方法来完成

此外，你应该检查你是否得到了一个非空的line，并开始打印它，看看它是否有你期望的所有标记

以下是更正后的代码片段：

Carmap = new HashMap<String,Car>();

//Change file path accordingly
File f = new File("C:\\Users\\XXX\\Documents\\CarFaxDB.txt");

//Check to see if file exists, else create file
if (f.exists()){
    String data[] = readFile(f);
    for (int i = 0; i < data.length; i++){

        if (data[i] != null){
            if (i > 0){
                String line = data[i];

                if(!StringUtils.isEmpty(line)) {
                    System.out.println(line);
                    StringTokenizer st = new StringTokenizer(line,",");

                    /* Check For More Tokens */
                    String VIN = st.hasMoreTokens() ? st.nextToken() : null;
                    /* Check For More Tokens */
                    String carMake = st.hasMoreTokens() ? st.nextToken() : null;
                    /* Check For More Tokens */
                    String carModel = st.hasMoreTokens() ? st.nextToken() : null;
                    /* Check For More Tokens */
                    int carYear = st.hasMoreTokens() ? Integer.parseInt(st.nextToken()) : 0;
                    data[i] = line;

                    Car car = new Car(VIN, carMake, carModel, carYear);
                    Carmap.put(car.getVIN(), car);
                }
            }
        }
    }
}

Answer 2

在调用StringTokenizer.nextToken()之前，必须检查StringTokenizer是否有更多的令牌。你是这样做的：

Carmap = new HashMap<String,Car>();
//Change file path accordingly
File f = new File("C:\\Users\\XXX\\Documents\\CarFaxDB.txt");
//Check to see if file exists, else create file
if (f.exists()){
    String data[] = readFile(f);
    for (int i =0; i<data.length; i++){

        if (data[i] != null){
            if (i>0){
                  String VIN, carMake, carModel = null;
                  int carYear = 0;
                  String line = data[i];
                  StringTokenizer st = new StringTokenizer(line,",");
                  if(st.hasMoreTokens()) {
                    VIN = st.nextToken();
                  if(st.hasMoreTokens())
                    carMake = st.nextToken();
                  if(st.hasMoreTokens())
                    carModel = st.nextToken();
                  if(st.hasMoreTokens())
                    carYear = Integer.parseInt(st.nextToken());
                  data[i]= line;
                  if(VIN != null && carMake != null && carModel != null && carYear > 0)
                  Car car = new Car(VIN, carMake, carModel, carYear);
                  Carmap.put(car.getVIN(), car);
                }
            }
        }
    }

}

请看这个question的答案，它解释了更多