What variable type for database

Question

Hi to all..
I would like to ask advice on what is the best type of variable to store and manage data. I am basically trying to build a small database of customer, names, address, tel number etc. The data is read and then saved into a simple excel or csv file. All is run locally, no need to connect to the web etc..
I had started with a two dimensional array, but then I realise that I cannot Re-dim the array, as records are added or deleted. So I found something called Arraylist, but I have problem in working in two dimensions (maybe that's why it is called a list?).
can anyone suggest what is the best structure for this, bearing in mind that the records are then shown in a jtable, as a list (with multiple columns).
thanks for your help

Answer 1

hey!!!
suggestion of jverd (above) is a very good suggestion and you should hava a look at it. keeping the records in a seperate object would be the best. technically you can then make an array of those objects and then write them into file via ObejctOutputStream.
but i think that what you want is to have the data in a 2-dimensional array so you can then create JTable.
well then you will, most probably, need to look into table models and create your own table model (extension of abstract table model) and then do operations on it.
sample:
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;
import java.awt.event.*;
public class neco extends JFrame implements ActionListener{
        private JScrollPane scroll = new JScrollPane();
        private JButton btn = new JButton("add row");
        private JTable tbl;
        public neco(){
                Object[] cols = {"first name","last name","phone number"};
                Object[][] data = {
                        {"first name","last name","phone number"},
                        {"second first name", "second last name","second phone number"}
                Container cn = this.getContentPane();
                cn.setLayout(new FlowLayout());
                cn.add(scroll);
                scroll.setViewport(this.getPort(tbl = new JTable(new MyTableModel(data,cols))));
                cn.add(btn);
                btn.addActionListener(this);
                cn.validate();
        private JViewport getPort(JComponent comp){
                JViewport port = new JViewport();
                port.setView(comp);
                return port;
        public void actionPerformed(ActionEvent ae){
                if(ae.getSource() == btn){
                        MyTableModel mtm = (MyTableModel)tbl.getModel();
                        mtm.addRow(new Object[]{"new first name","new last name","new phone number"});
                        scroll.validate();
        public static void main(String[] vik){
                neco n = new neco();
                n.setSize(800,600);
                n.setVisible(true);
                n.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        class MyTableModel extends AbstractTableModel{
                Object[][] data;
                Object[] cols;
                public MyTableModel(Object[][] data, Object[] cols){
                        this.data = data;
                        this.cols = cols;
                @Override
                public String getColumnName(int col){
                        return cols[col].toString();
                public void addRow(Object[] row){
                        Object[][] newData = new Object[this.getRowCount() + 1][this.getColumnCount()];
                        //now copy the old object[][] array into this new one
                        for(int count=0;count<this.getRowCount();count++){
                                newData[count] = data[count];
                        //and now add the new row
                        newData[newData.length - 1] = row;
                        //make data our newData
                        data = newData;
                        fireTableRowsInserted(0,data.length - 1);
                public Object getValueAt(int row, int col){
                        return data[row][col];
                public int getColumnCount(){
                        return cols.length;
                public int getRowCount(){
                        return data.length;
}in your (MyTableModel) you can add methods for getting rows, or column, or whatever you want and then you will have all the data that you need.
hope this will help
v.v.