import java.awt.*;

import javax.swing.*;

import java.awt.event.*;

class ButtonsHW implements ActionListener

{

int count;

JFrame fr;

String s1[] = {"1","2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","Show","Reset"};

JButton b[] = new JButton[s1.length];

JPanel p1,p2;

ButtonsHW()

{

fr = new JFrame("Button");

fr.setSize(900,800);

fr.setLayout(new GridLayout());

p1 = new JPanel();

p1.setLayout(new GridLayout(4,4));

p2 = new JPanel(new GridLayout(2,1));

for(int i=0;i<s1.length;i++)

{

b[i] = new JButton(s1[i]);

}

for(int i=0;i<s1.length-2;i++)

{

b[i].setVisible(false);

}

p1.setSize(800,800);

p2.setSize(100,800);

for(int i=0;i<s1.length;i++)

{

p1.add(b[i]);

if(i>=16)

{

p2.add(b[i]);

b[i].addActionListener(this);

}

}

fr.add(p1);

fr.add(p2);

fr.setVisible(true);

}

public void actionPerformed(ActionEvent e)

{

if(e.getSource()==b[17])

{

count = 0;

for(int i=0;i<s1.length-2;i++)

{

b[i].setVisible(false);

}

}

if(e.getSource()==b[16])

{

while(true)

{

if(count==16)

{

JOptionPane.showMessageDialog(fr,"All buttons are visible","msg",JOptionPane.INFORMATION_MESSAGE);

break;

}

int x = (int)(Math.random()*16);

if(b[x].isVisible())

continue;

b[x].setVisible(true);

count++;

break;

}

}

}

public static void main(String ...S)

{

new ButtonsHW();

}

}