The contents of a Do While loop is always executed at least once. Therefore the boolean variable isNotAnInteger need not be set to true.
/**
* keep prompting for an integer until the user supplies one
* using an input dialog box ,try/catch and a boolean variable
* all with a while loop
*/
public int inputInteger(){
String prompt, str;
int num= 0;
boolean isNotAnInteger;
prompt = "Enter an integer: ";
do {
str = JOptionPane.showInputDialog(prompt,null);
try{
num = Integer.parseInt(str);
isNotAnInteger = false;
}
catch(NumberFormatException e){
isNotAnInteger = true;
prompt = "You MUST enter an integer: ";
}
}while (isNotAnInteger);
return num;
}