未正确初始化的对象数组

Question

使用此代码,我尝试将包含数据的文件加载到对象数组中.我没有正确地对象中的字段,因为当我运行此代码时,我得到一个NullPointerException.数组在那里,甚至是正确的大小,但字段没有初始化.我该怎么解决这个问题？

这是代码:

public class aJob {
  public int job;
  {
    job = 0;
  }
  public int dead;
  {
    dead = 0;
  }
  public int profit;
  {
    profit = 0;
  }
}

public class Main {
  public static void main(String[]args) throws IOException {
    File local = readLines();
    Scanner getlength = new Scanner(local);
    int lines = 0; 

    while (getlength.hasNextLine()) {
      String junk = getlength.nextLine();
      lines++;
    }
    getlength.close();

    Scanner jobfile = new Scanner(local);  // check if empty                            

    aJob list[] = new aJob[lines];
    aJob schedule[] = new aJob[lines];
    int index = 0;
    list[index].job = jobfile.nextInt();
  }

  public static File readLines() throws IOException 
  {
    try {
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    } catch (Exception e) {
      // ignore exceptions and continue
    }

    JFileChooser chooser = new JFileChooser();
    try {
      int code = chooser.showOpenDialog(null);
      if (code == JFileChooser.APPROVE_OPTION) {
        return chooser.getSelectedFile(); 
      }
    } catch (Exception f) {
      f.printStackTrace();
      System.out.println("File Error exiting now.");
      System.exit(1);
    }
    System.out.println("No file selected exiting now.");
    System.exit(0);
    return null;
  }
}

Answer 1

声明一个数组是不够的.您必须使用对象实例填充它.

aJob list[] = new aJob[lines];
aJob schedule[] = new aJob[lines];

for (int i = 0; i < lines; i++){ list[i] = new aJob(); schedule[i] = new aJob(); }