So I was trying to add elements into my list. But for some reason the words inside the list are very very small.... is there anyway to increase the font? I tried setFont, doesn't work. :(

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.event.DocumentListener;




public class sub extends JFrame implements ActionListener{
	private JList list; 
	private JButton addButton = new JButton("Add"); 
	private JButton delButton = new JButton("Delete");
	private JTextField item = new JTextField(10);
	private String [] s = new String[20];
	
public sub(){
	
      list = new JList(s);
      list.setLayout(new BorderLayout());
      list.setFont(new Font("Courier New", Font.ITALIC, 12));
      
      JScrollPane listScrollPane = new JScrollPane(list);
      
      list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
      list.setSelectedIndex(0);
      list.setVisibleRowCount(5);
      
      addButton.setEnabled(true);
      addButton.addActionListener(this);
      delButton.setEnabled(false);
      delButton.addActionListener(this);
      
      item.addActionListener(this);
      
      
      JPanel panel = new JPanel();
      panel.setLayout(new BoxLayout(panel, BoxLayout.LINE_AXIS));
      panel.add(delButton);
      panel.add(Box.createHorizontalStrut(5));
      panel.add(new JSeparator(SwingConstants.VERTICAL));
      panel.add(Box.createHorizontalStrut(5));
      panel.add(item);
      panel.add(addButton);
      panel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));   
     
      add(listScrollPane, BorderLayout.CENTER);
      add(panel, BorderLayout.PAGE_END);
      
}



public static void main (String[] args){
	sub sub = new sub();
	sub.setVisible(true);
	sub.setDefaultCloseOperation(EXIT_ON_CLOSE);
	sub.setTitle("Bank Account");
	sub.setSize( 250,250 );
	sub.setLocation(600, 400);
}



public void actionPerformed(ActionEvent e) {
	if(e.getSource() == addButton){
		System.out.println("ADD");
		int index = list.getSelectedIndex();
        if (index == -1) { //no selection, so insert at beginning
            index = 0;
        } else {           //add after the selected item
            index++;
        }
        
        s[index] = item.getText();

        item.requestFocusInWindow();
        item.setText("");
        item.setFont(new Font("Courier New", Font.ITALIC, 12));
        list.setSelectedIndex(index);
        list.ensureIndexIsVisible(index);
	}
	
	else if(e.getSource() == delButton){
		System.out.println("DEL");
	}
	
}



}

Setting font size isnt ur problem... Its your layout problem.

where can i change it to let the text in the list visible?

Passing the empty string array to the constructor of your JList is causing the weird font sizing issue.

If you want to add and remove items from your list, use a DefaulListModel instead of an array.

The reason why i used array is because i wanted to use FileIO to save and load the array elements into a txtfile so i can retrieve the info the next time i run the prog.

You can use any means you wish to load and save the elements with a DefaultListModel. You aren't limited to an array for that.

DefaultListModel implements Serializable, so you can read/write one with a single Object I/O call, or use XMLEncoder/Decoder to write & read the whole contents as XML string data, also in a single call.