小编Ron*_*gan的帖子

我想使用分隔符","提取文件中的第一列,并将其保存到新文件中.输出生成此异常:

Exception in thread "main" java.lang.NullPointerException
    at Extract.main(Extract.java:26)

这是我使用的代码,但我不确定它是否正确:

public class Extract {
    public Extract(){
    }
     public static void main(String[] args) {
        BufferedReader in = null;
        try {
            BufferedWriter out = new BufferedWriter(new FileWriter("/home/omar/Téléchargements/nursery.tmp"));
            in = new BufferedReader(new FileReader("pima.txt"));
            String read = null;
            while ((read = in.readLine()) != null) {
                read = in.readLine();
                String[] splited = read.split(",");
                if (splited.length > 0)
                {
                    out.append(splited[0].toString());
                    out.newLine();
                }
            }
        } catch (IOException e) {
            System.out.println("There was a problem: " + e);
            e.printStackTrace();
        } …

我想String使用分隔符","在文件中提取第一个.为什么此代码生成大于一行的行数？

public static void main(String[] args) {
    BufferedReader in = null;
    try {
        in = new BufferedReader(new FileReader("irisAfter.txt"));
        String read = null;
        while ((read = in.readLine()) != null) {
            read = in.readLine();
            String[] splited = read.split(",");
            for (int i =0; i<splited.length;i++) {
                System.out.println(splited[0]);
            } 
        }
    } catch (IOException e) {
            System.out.println("There was a problem: " + e);
            e.printStackTrace();
    } finally {
        try {
            in.close();
        } catch (Exception e) { e.printStackTrace(); }
    }
}