Question

您好我正在尝试编写一个程序，该程序从逗号分隔的文本文件中获取第三行，然后将其传递给WeatherDataPoint类中的getData方法，在该类中，它将字符串拆分为逗号上的单独字符串。然后我希望将字符串变量日期设置为dataLine2 [7]的值。然后通过从驱动程序类调用getDate方法打印出日期字符串。

public class driver

{

public static void main(String[] args) 
{
    WeatherDataPoint weather = new WeatherDataPoint();
    String dataLine1 = "";
    String inputFile = "weatherdata.csv";
    Scanner readFile = null;
    try
    {
        readFile = new Scanner (new File(inputFile));
    }
    catch (FileNotFoundException ex)
    {
        System.out.println("Error file not found");
        System.exit(1);
    }

    while (readFile.hasNextLine())
    {

        dataLine1 = readFile.nextLine();

        weather.getData(dataLine1);



    }

    System.out.println(String.format("%s",weather.getDate()));
}

}

public class WeatherDataPoint {
private String date = "";
private String temperature;


public void getData(String dataLine1)
{
    String [] dataLine2 = dataLine1.split(",");
    date = dataLine2[7];
    //long epoc = Long.parseLong(fields[DATE_POS]);
    //Date d = new Date(epoc * 1000);

}


public String getDate()
{
    //return String.format("%s", (date));
    return date;
}

当我运行程序时，我收到错误

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 7

编辑这是文本文件中的一行

"1452386100","1","5","29.002591800284698","77.91272888363851","78.21244075516647","86.27","49.8",,"99","0",,"0",,"0","0","49.53002056234984","49.8","49.8",,,,,,,,,,,,,,,,,,,,,"100",,,,,,,,,,,,

我在描述程序时犯了一个错误，我实际上想要处理文件中的所有数据，但跳过前三行抱歉这个混乱。将dataLine [7]更改为dataLine [0]也可以。

Answer 1

尝试替换它：

 String [] dataLine2 = dataLine1.split(",");
date = dataLine2[7];

使用：

  String [] dataLine2 = dataLine1.split(",");
  date = dataLine2[dataLine2.length-1];

因为在数组dataLine2中你没有第7个索引中的元素。

Answer 2

您正尝试从数组dataLine2的第8个单元格中获取值。该异常表明该索引超出范围，这意味着数组dataLine2没有8个单元格。

这意味着您的字符串dataLine1似乎在文件的一行中没有8个部分。

尝试打印dataLine2变量的大小，以便您可以看到一行中有多少个String部分。然后通过遍历数组中的单元格来获取每个单元格。

修改

如果您需要跳过文件的前3行，则需要执行以下操作：

WeatherDataPoint weather = new WeatherDataPoint(); String dataLine1 = ""; String inputFile = "weatherdata.csv"; Scanner readFile = null; try { readFile = new Scanner (new File(inputFile)); } catch (FileNotFoundException ex) { System.out.println("Error file not found"); System.exit(1); } int linesPassed = 0; while (readFile.hasNextLine()) { String row = readFile.nextLine(); linesPassed++; if (linesPassed > 3) { dataLine1 = row; weather.getData(dataLine1); } } System.out.println(String.format("%s",weather.getDate()));

如果你需要处理整行，最好保存整个String []并按你的意愿处理它。以下是示例代码：

private ArrayList date = new ArrayList＆lt;＆gt;（）; 私人字符串温度;

public void getData(String dataLine1){ String[] rowParts =dataLine1.split(","); for(String part : rowParts) date.add(part); } public String getDate() { //do some processing here, I`ve added a dummy print code String allValues = ""; for(String val : date) allValues += val + " "; return allValues; }

对于文件中的示例数据，如下所示：

"1452386100","1","5","29.002591800284698","77.91272888363851","78.21244075516647","86.27","49.8",,"99","0",,"0",,"0","0","49.53002056234984","49.8","49.8",,,,,,,,,,,,,,,,,,,,,"100",,,,,,,,,,,, "1452386100","1","5","29.002591800284698","77.91272888363851","78.21244075516647","86.27","49.8",,"99","0",,"0",,"0","0","49.53002056234984","49.8","49.8",,,,,,,,,,,,,,,,,,,,,"100",,,,,,,,,,,, "1452386100","1","5","29.002591800284698","77.91272888363851","78.21244075516647","86.27","49.8",,"99","0",,"0",,"0","0","49.53002056234984","49.8","49.8",,,,,,,,,,,,,,,,,,,,,"100",,,,,,,,,,,, "0","1","2","3","4","5","6","7", "0","1","2","3","4","5","6","7",

输出如下：

"0" "1" "2" "3" "4" "5" "6" "7" "0" "1" "2" "3" "4" "5" "6" "7"

随意扩展和修改。

Answer 3

确保csv文件中的第8列有日期数据。

无法将字符串从一个类传递到另一个类

3 个答案: