Question

I have a small issue when I run into while using arraylists in Java. Essentially I am hoping to store an array in an arraylist. I know that arraylists can hold objects, so it should be possible, but I am not sure how.

For the most part my arraylist (which is parsed from a file) is just holding one character as a string, but once in a while it has a series of characters, like this:

    myarray
0    a
1    a
2    d
3    g
4    d
5    f,s,t
6    r

Most of the time the only character I would care about in the string residing at position 5 is the f but occasionally I may need to look at the s or the t as well. My solution to this is to make an array like this:

      subarray
0     f 
1     s
2     t

and store subarray in position 5 instead.

    myarray
0    a
1    a
2    d
3    g
4    d
5    subarray[f,s,t]
6    r

I tried to do this with this code:

 //for the length of the arraylist
 for(int al = 0; al < myarray.size(); al++){
      //check the size of the string
      String value = myarray.get(al);
      int strsz = value.length();
      prse = value.split(dlmcma);
      //if it is bigger than 1 then use a subarray
      if(strsz > 1){
          subarray[0] = prse[0];
          subarray[1] = prse[1];
          subarray[2] = prse[2];
      }
      //set subarray to the location of the string that was too long
      //this is where it all goes horribly wrong
      alt4.set(al, subarray[]);
  }

This isn’t working the way I would like though. It won’t allow me to .set(int, array). It only allows .set(int, string). Does anyone have suggestions?

Answer 1

The easiest approach would be to have an ArrayList of ArrayList.

ArrayList<ArrayList<String>> alt4 = new ArrayList<ArrayList<String>>();

However, this probably isn’t the best solution. You may want to rethink your data model and look for a better solution.