java - 在 Java vector 中插入 null

Question

我正在尝试使用标记器将 .txt 文件的内容插入到 vector 中；但没有插入特定文件。后来我需要将 vector 的内容稍后传递给 jtable。问题是 .txt 的第一行有空值，所以它没有被插入它跳过第一行并继续前进..有没有办法将 null 存储在 vector 中并将其替换为“”？

private void loadSecondPreview() {
  String aLine;
  recordData = new Vector();
  columnNames = new Vector();

  try {
    FileInputStream fin = new FileInputStream(dataFile);
    BufferedReader br = new BufferedReader(new InputStreamReader(fin));
    // extract column names
    if (delimiter == ",") {
      StringTokenizer st1 =
        new StringTokenizer(br.readLine(), ",");
      while (st1.hasMoreTokens()) {
        columnNames.addElement(st1.nextToken());
    }
    // extract data
    while ((aLine = br.readLine()) != null) {
      StringTokenizer st2 =
        new StringTokenizer(aLine, ",");
      while (st2.hasMoreTokens()) {
        recordData.addElement(st2.nextToken());
      }
    }
  } else if (delimiter == "\t") {
    StringTokenizer st1 =
      new StringTokenizer(br.readLine(), "\t");
    while (st1.hasMoreTokens()) {
      if (st1.equals(null)) {
        columnNames.addElement(" ");
      } else {
        columnNames.addElement(st1.nextToken());
      }
    }
    // extract data
    while ((aLine = br.readLine()) != null) {
      StringTokenizer st2 =
        new StringTokenizer(aLine, "\t");
      while (st2.hasMoreTokens()) {
        if (st2.equals(null)) {
          recordData.addElement(" ");
        } else {
          recordData.addElement(st2.nextToken());
        }
      }
    }
  }
  br.close();

  System.out.println("Column vector size:" + columnNames.size());
  System.out.println("Record vector size:" + recordData.size());

  for (int x = 0; x < columnNames.size(); x++) {
    System.out.println("Column vector:" + x + " " + columnNames.elementAt(x));
  }

  for (int x = 0; x < recordData.size(); x++) {
    System.out.println("Record vector:" + x + " " + recordData.elementAt(x));
  }

开/关:
**列 vector 大小:0
记录 vector 大小:5
记录 vector :0 8
记录 vector :1 8.100
记录 vector :2 8.200
记录 vector :3 9
记录 vector :4 9.8

测试文件记录:第一行有两个空值列

8 8.100
8.200
9 9.8

Answer 1

尝试这个

BufferedReader in = new BufferedReader(new FileReader(loc + fname));
    ArrayList<String []> input = new ArrayList<String []>();
    String [] temp;
    String line;
    String stemp = null, sprev;
    ArrayList<String> comp = new ArrayList<String>();
    while((line = in.readLine())!= null)
    {
        StringTokenizer st = new StringTokenizer(line, ",", true);
        temp = new String [15];
        int i = 0;
        while(st.hasMoreTokens())
        {
            sprev = stemp;
            stemp = st.nextToken(); 
            if((stemp.equals(sprev)) && stemp.equals(","))                
            {
                //it is a null field
                temp[i++] = null;                    
            }
            else if(!(stemp.equals(",")))
            {
                temp[i++] = stemp;
            }
        }
        input.add(temp);

为我工作