Here is an applet program that will increment and decrement the integer value. There are two buttons in an applet for increment and decrement respectively. On clicking these button, value will get incremented and decremented.

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class Final extends Applet {
    public int testone = 0;
    public void init()    {
        Button one = new Button("Increase");
        Button two = new Button("Decrease");
        one.addActionListener(new ActionListener(){
             public void actionPerformed(ActionEvent e) {
        increasetestone();
        repaint();
          }
        });
         two.addActionListener(new ActionListener(){
             public void actionPerformed(ActionEvent e) {
        decreasetestone();
        repaint();
          }
        });
        add(one);
        add(two);
    }
    public void paint(Graphics g)
    {
        g.drawString("Total: " + gettestone(),20,50);
    }

    public synchronized int gettestone()
    {
        return testone;         
    }
    public synchronized void increasetestone() {
        testone++;
    }
    public synchronized void decreasetestone() {
        testone--;
    }
}