使用 Java 从文本文件中逐列提取数据
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extract data column-wise from text file using Java
提问by Aman Chawla
I'm working under Java and want to extract data according to column from a text file.
"myfile.txt" contents:
我在 Java 下工作，想根据文本文件中的列提取数据。
“myfile.txt”内容：
ID SALARY RANK
065 12000 1
023 15000 2
035 25000 3
076 40000 4
I want to extract the data individually according to any Column i.e ID, SALARY, RANK etc
Basically I want to perform operations on individual data according to columns.
我想根据任何列单独提取数据，即 ID、SALARY、RANK 等
基本上我想根据列对单个数据执行操作。
I've listed the data from "myfile.txt" by using while loop and reading line-by-line:
我已经通过使用 while 循环和逐行读取列出了“myfile.txt”中的数据：
while((line = b.readLine()) != null) {
stringBuff.append(line + "\n");
}
link: Reading selective column data from a text file into a list in Java
链接：在 Java 中将文本文件中的选择性列数据读取到列表中
Under bove link it is written to use the following: String[] columns = line.split(" ");
在 bove 链接下，它被编写为使用以下内容： String[] columns = line.split(" ");
But how to use it correctly, please any hint or help?
但是如何正确使用它，请提供任何提示或帮助？
回答by mrcaramori
You can use a regex to detect longer spaces, example:
您可以使用正则表达式来检测更长的空格，例如：
String text = "ID SALARY RANK\n" +
"065 12000 1\n" +
"023 15000 2\n" +
"035 25000 3\n" +
"076 40000 4\n";
Scanner scanner = new Scanner(text);
//reading the first line, always have header
//I suppose
String nextLine = scanner.nextLine();
//regex to break on any ammount of spaces
String regex = "(\s)+";
String[] header = nextLine.split(regex);
//this is printing all columns, you can
//access each column from row using the array
//indexes, example header[0], header[1], header[2]...
System.out.println(Arrays.toString(header));
//reading the rows
while (scanner.hasNext()) {
String[] row = scanner.nextLine().split(regex);
//this is printing all columns, you can
//access each column from row using the array
//indexes, example row[0], row[1], row[2]...
System.out.println(Arrays.toString(row));
System.out.println(row[0]);//first column (ID)
}
回答by Majid Laissi
while((line = b.readLine()) != null) {
String[] columns = line.split(" ");
System.out.println("my first column : "+ columns[0] );
System.out.println("my second column : "+ columns[1] );
System.out.println("my third column : "+ columns[2] );
}
Now instead of System.out.println, do whatever you want with your columns.
现在代替System.out.println，对您的列做任何您想做的事情。
But I think your columns are separated by tabsso you might want to use split("\t")instead.
但我认为你的列被分隔，tabs所以你可能想split("\t")改用。
