How do i make an error message come up if i type a letter not a number

Question

Hi i have a problem with a program that when i type a letter where a number should be in JOptionPane the program crashes as it should. I would like it to return an error message i know how to return an error message if an incorrect number is returned if (sTimeHours >24 || eTimeHours > 24)
My question is what do you type in for an incorrect letter.

Answer 1

User entry Is what i think tou mean here is some of the code
while(true){
String one = JOptionPane.showInputDialog(null,"Please enter your start hours and minutes in 24 hr time\n with a - between the hours & minutes" );
     String two = JOptionPane.showInputDialog(null,"Please enter your finnish hours and minutes in 24 hr time\n with a - between the hours & minutes");
String[] startTime = one.split( "-" ), endTime = two.split( "-" );
int sTimeHours = Integer.parseInt( startTime[0] ), sTimeMins = Integer.parseInt( startTime[1] );
int eTimeHours = Integer.parseInt( endTime[0] ), eTimeMins = Integer.parseInt( endTime[1] );
if ( sTimeHours > 24 || eTimeHours > 24 || sTimeMins > 60 || eTimeMins > 60 ) {
if (sTimeHours > 24 || eTimeHours > 24) {
JOptionPane.showMessageDialog(null," HOURS must be less than 24 Hr ", "ERROR!" , JOptionPane.ERROR_MESSAGE);
if (sTimeMins > 60 || eTimeMins > 60) {
JOptionPane.showMessageDialog(null," MINUTES must be less than 60 Sec ", "ERROR!" , JOptionPane.ERROR_MESSAGE);
If some one enters a letter instead of a number how do i give them an error message instead of the program crashing. Also on a further note i have a return to the start statement on this code which works for the minutes but the hours just add up and the program ends any ideas.
Once again if the code dose not present correctly i am sorry i am trying to work out how the code button works