Question

What I want to do is, read a file with multiple words in a single line and then add each word in 2d arraylist. This should be such that [[kevin,kevin,kevin][jobs,jobs,jobs]]

the code below works well but it does like this [[kevin,kevin,kevin,jobs,jobs,jobs]]

It should be done by using nested for, but can someone please help?

public void getReference() throws IOException
    {
        String line=null;

            connectRead("computer");
            //this is a method that reads a file in a format kevin kevin kevin kevin
            try
            {
                reference.add(new ArrayList<String>());
                while ((line=bufferedReader.readLine())!=null)
                {
                    st = new StringTokenizer(line); 

                    for ( int i = 0 ; i < st.countTokens() ; i++)
                    {       
                        reference.get(i).add(st.nextToken());
                        reference.get(i).add(st.nextToken());
                        reference.get(i).add(st.nextToken());
                        reference.get(i).add(st.nextToken());  
                    }

                }
                System.out.println(reference);

                bufferedReader.close();
            }
            catch ( IOException e )
            {
               System.out.println(e);
            }      

    }

text in file looks something like this

kevin usa hacker
wozniak usa hacker
jobs usa hacker

Answer 1

You are always getting references.get(i), where i=0, so whenever new line is read insertion of token starts from the ArrayList at zeroth index.

try this, but this structure looks a bit confusing to me. may be showing structure of your input file helps to make code better.

public void getReference() throws IOException
{
    String line=null;

        connectRead("computer");
        //this is a method that reads a file in a format kevin kevin kevin kevin
        try
        {
            reference.add(new ArrayList<String>());
            int indexOfReferences =0 ;
            while ((line=bufferedReader.readLine())!=null)
            {
                st = new StringTokenizer(line); 

                for ( int i = 0 ; i < st.countTokens() ; i++)
                {       
                    reference.get(indexOfReferences).add(st.nextToken());
                }
               indexOfReferences++;

            }
            System.out.println(reference);

            bufferedReader.close();
        }
        catch ( IOException e )
        {
           System.out.println(e);
        }      

}