将数据从对象的数组列表和对象内的数组列表写入文本文件

Question

say i have a an arraylist that contains objects of type employee that have instance variables such as id,first name, last name, tel and also with each object there is another arraylist that contains numerical data and I want to write all that data out to a txt file , what would be the best way of doing this

My current thinking is that I could iterate through with a for loop the first arraylist to write the instance variables, then have a inner for loop to make get calls to the arraylist in the objects. I have got the first for loop working and writing, just trying to work out how to get the second inner loop to get the other data. It is important that the data is written in the correct order which is id, firstname, lastname, tel and then followed by the numerical data in the order it is stored, then on to the next employee to write in the same order.

Im not sure how how to achieve this exactly and am still experimenting with the code but would appreciate to suggestions on how best to go about this.

UPDATE

Seems like I have it working - i did the following:

PrintStream out = new PrintStream (new FileOutputStream("output.txt")); 
    for (int a=0;a<emp.size();a++)
    {
    empNumber = emp.get(a).empNumber;
    out.println(empNumber); 
    fName = emp.get(w).fName;
    out.println(fName); 
    lName = emp.get(w).lName;
    out.println(lName); 
    telNum = emp.get(w).telNum;
        for (int l=0;l<emp.get(w).dataNums.size();l++)
        {
            out.println(emp.get(w).dataNums.get(l));
        }

    out.close();    
    }

There are probably much more sophisticated ways but Im happy enough as a beginner I worked it out myself.

thanks for the replies though

Answer 1

The best way in my opinion is to implement a toString() method for each one of your objects. Then just use toString() on your arrayList with employee. And lastly use for example fileWriter to write this String to a txt.