Java Can'；t将字符串从一个类传递到另一个类

您好，我正在尝试编写一个程序，从逗号分隔的文本文件中获取第三行，然后将其传递到WeatherDataPoint类中的getData方法，在该方法中，它将字符串拆分为逗号上的单独字符串。然后我希望字符串变量date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 

{

}

当我运行程序时，我得到了错误

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

编辑此处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，我实际上想处理文件中的所有数据，但跳过了前三行，很抱歉混淆了。将数据线[7]更改为数据线[0]同样有效。

尝试替换此选项：

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

与：

---

因为在数组

dataLine2

中，第7个索引中没有元素。

您试图从数组

dataLine2

的第8个单元格中获取值。异常状态表示此索引超出范围，这意味着数组

dataLine2

没有8个单元格

这意味着字符串

dataLine1

在文件的一行中似乎没有8个部分

尝试打印

dataLine2

变量的大小，以便查看一行包含多少字符串部分。然后通过遍历数组中的单元格来获取每个单元格

编辑：

如果需要跳过文件的前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()));

"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",

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

如果需要处理整行，最好保存整个字符串[]，并根据需要进行处理。下面是一个示例代码：

private ArrayList date=new ArrayList（）； 私有串温度

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：

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()));

"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",

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

输出如下：

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()));

"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",

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

---

您可以根据需要随意展开和修改。

确保在csv文件的第8列有日期数据。

错误消息不是不言自明的吗？该行上的记录少于8条，因此是例外。使用调试器。或者将值打印到控制台。您问题中的代码获取文件中的所有行，而不是如您所述的第三行。如果这段代码有效，它将只打印文件最后一行的数据。如果你的档案只有三行，我想你会没事的，但我怀疑这是你想要的…从技术上说，是第八单元。数组是零IndexedHanks，在我进一步讨论字符串的8个部分时输入error。编辑。谢谢你的回复，我添加了一个数据文件中的一行是什么样子的示例。这很奇怪，我测试了你的代码，输出结果应该是“49.8”。检查此文件是否在项目文件夹中。您可能有另一个同名但数据不同的文件。为了在指向文件路径时读取该文件，需要将其放置在项目文件夹中。