int number = 0; // or any application default value
try {
    number = Integer.parseInt(input);
} catch (NumberFormatException nfe) {
    // do whatever you need to do if you get an invalid number
    // you can put the try catch in a loop and keep asking for a 
    // value until you don't get a valid one
    
      // If you want to use the default value in case of an
    // invalid number you can do nothing in here
}