Question

I have an arraylist and each element of the arrayList contains a small arrayList of data.

I need to create a table from this data. What would you recommend being the best route to take with solving this?

Thanks in advance for any help

Answer 1

To display a GUI table of a List of lists, I would create a class that implements the ‘TableModel’ interface, and has a constructor that takes in your ‘List>’

public class ListTableModel <T> implements TableModel {

    private List<List<T>> source;

    public ListTableModel(List<List<T>> source) {

        this.source = source;

    }


    //Override 'getRowCount' 
    //The row count would be calculated as the size of the outer list.
    @Override
    public int getRowCount() {
        return source.size();
    }

    //Override 'getColumnCount'
    //The column count would be calculated as the max size of the inner lists
    @Override
    public int getColumnCount() {
        int max = 0;
        for(List<T> row : source) {
            max = Math.max(max, row.size());
        }
        return max;
    }

    //Override 'getColumnName'
    //Lets go ahead and just give a unique name to each column based on the index.
    //This could be populated from an input taken by the constructor, but we
    //won't worry about that now.
    @Override
    public String getColumnName(int columnIndex) {
        return "Column " + columnIndex;
    }

    //Override 'getColumnClass'
    //The class would technically be the generic type 'T', so to get this we 
    //will simply just get the calss of the first element.
    @Override
    public Class<?> getColumnClass(int columnIndex) {
        return source.get(0).get(0).getClass();
    }


    //Override 'isCellEditable'
    //I'm going to assume we don't want cell to be editable.
    @Override
    public boolean isCellEditable(int rowIndex, int columnIndex) {
        return false;
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        List<T> row = source.get(rowIndex);
        if(columnIndex >= row.size())
            return null;
        else 
            return row.get(columnIndex);
    }

    @Override
    public void setValueAt(Object aValue, int rowIndex, int columnIndex) {
        //required but we will assume that you cannot change the source list
        //if we needed to, it wouldn't be too difficult to implement.
    }

    @Override
    public void addTableModelListener(TableModelListener l) {
        //required but not used (will only be used if the source could change)
    }

    @Override
    public void removeTableModelListener(TableModelListener l) {
        //required but not used (will only be used if the source could change)
    }

}

you would use this model with your list like so:

List<List<String>> myList = new ArrayList();

//Populate 'myList'...

JTable table = new JTable();

//Add table to view...

table.setModel(new ListTableModel(myList));

EDIT I can show you how to implement TableModel if you would like.