JOptionPane

import javax.swing.JOptionPane;
import javax.swing.JTextArea;

public class pyra2
{

 public static void main(String[] args)
 {
  String s;
  int s2;
 
  s = JOptionPane.showInputDialog("How many lines ?");
 
  s2 = Integer.parseInt(s);

  pyramid(s2);
  System.exit(0);
 }
 public static void pyramid(int a)
 {
  int i,j,k;
  int i2,j2,k2;

  JTextArea area= new JTextArea();

  for (i=1;i <= a;i++){
  for (j=1;j<=20-i;j++) area.append(" ");
  for(k=1;k <=(2*i)-1;k++) area.append("*");if (k ==2*i)area.append("\n");

  for (i2=a;i2>=1;i2--){
  for (j2=1;j2<=20-i2;j2++)area.append (" ");
   for (k2=1;k2 <=(2*i2)-1;k2++) area.append("*");if (k2 == 2*i2) area.append("\n");}
  JOptionPane.showMessageDialog(null,area);
 }
}