Pirámide en serie en java

Hi as per request of my friend’s third term … Erick by a program for one of his friends from 1st semester to the class of Professor Angelica of FCBIyT I leave this program hoping one day I ordered it helps someone, cordial greetings and leave your comment.
You should print:
1
212
32123
4321234
543212345
65432123456
etc …

[java]
import static javax.swing.JOptionPane.*;
public class Triangulo{
public static void main(String Ar[]){
String cad="";
int lineas02=Integer.parseInt(showInputDialog("Dame el numero de lineas"));
int lineas=1;
while(lineas<=lineas02){
for(int i=lineas;i>1;i–)
cad+=" "+i;
for(int j=1; j<=lineas;j++)
cad+=" "+j;
lineas++;
cad+="\n";
}
showMessageDialog(null,"el valor es \n"+cad);
}//end main
}
[/java]