How to get data from a JTable?

Question

OK, I want to get all the data from the first column of a JTable. I though the best way would be pulling it in to a ArrayList, so I made one. I also made an instance of a TableModel:

static DefaultTableModel model = new javax.swing.table.DefaultTableModel(); 
f.data.setModel(model); //f.data is the JTable

public static final void CalculateTotal(){
    ArrayList<String> numdata = new ArrayList<String>();

  for(int count = 1; count <= model.getRowCount(); count++){
      numdata.add(model.getValueAt(count, 1).toString());

  }
  System.out.println(numdata); 
}

This gives me a NullPointerException (cue screams). What am i doing wrong?

Answer 1

I don't know those classes well, but I would guess you'll have to count from zero:

for (int count = 0; count < model.getRowCount(); count++){
  numdata.add(model.getValueAt(count, 0).toString());
}

In Java, it is usual to count from 0 (like in most C-like languages)...

Answer 2

It is best if you could post SSCCE that shows model initialization and its population with data. Also include details of the exception as there could be multiple sources for the problem.

Here is a demo based on @CedricReichenbach correction:

import java.util.ArrayList;
import java.util.List;

import javax.swing.table.DefaultTableModel;

public class TestModel {
    public static void main(String s[]) {
        DefaultTableModel model = new javax.swing.table.DefaultTableModel();    

        model.addColumn("Col1");
        model.addColumn("Col2");

        model.addRow(new Object[]{"1", "v2"});
        model.addRow(new Object[]{"2", "v2"});

        List<String> numdata = new ArrayList<String>();
        for (int count = 0; count < model.getRowCount(); count++){
              numdata.add(model.getValueAt(count, 0).toString());
        }

        System.out.println(numdata); 
    }
}

The result is:

[1, 2]