Question

I’ve read many topic on stackoverflow,and google, about this argument but i can’t orient myself with writing custom ArrayList into files !
I’ve an ArrayList of type “CustomType”. “CustomType” have two String variable : “name” and “description”.

I want to save this ArrayList for reading it after closing and reopening my app.
Does anyone help me doing this? and does anyone explain me what happen when i save/read?

Answer 1

you could write it simply as a csv file, like this,

1,name,desc
2,name2,desc2
3,name3,desc3
...

or you could use gson library – http://code.google.com/p/google-gson/, to convert it into a json string and then write it to a file, that way when you read it you could directly get the object from json,

i would personally use the second method,

Edit: for writing to csv

try
{
  FileWriter writer = new FileWriter("<path>/MyFile.csv");
  while(lst.next())
  {
     for(int i = 0; i < columnSize; i++)
     {
        writer.append(i);
        writer.append(',');
        writer.append(lst.get(i).getName());
        writer.append(',');
        writer.append(lst.get(i).getDesc());
     }
     writer.append('\n');
  }
}
catch(Exception e)
{
  e.printStackTrace();
}

(assuming the object in side the ArrayList has methods getName() and getDesc() )

this might be helpful in reading it again,

Get and Parse CSV file in android