need help with validation..

[nadykool]

i wont to includ a validation for these...but i dont no how !!?

if (x==1)
{
inp =JOptionpane.showInputDialoge("Enter Number of miles')
int y= Integer.parseInt(inp);
double miles=c.KmToMiles(y);
JOptionpane.showmessageDialog(null,"Miles="+miles);

}


if (x==2)
{
inp =JOptionpane.showInputDialoge("Enter Number of km ")
int y= Integer.parseInt(inp);
double km=c.MilesToKm(y);
JOptionpane.showmessageDialog(null,"km="+km);

}

how can i do it ..!!!!!!???