Painful menstrual periods are periods in which a woman has crampy lower abdominal pain, sharp or aching pain that comes and goes, or possibly back pain. Some pain during your period is normal, but a large amount of pain is not. The medical term for painful menstrual periods is dysmenorrhea.
When an exception occurs, we say that the exception is thrown. For example, we say that Integer.parseInt(str) throws an exception of type NumberFormatException when the value of str is illegal. When an exception is thrown, it is possible to catch the exception and prevent it from crashing the program. This is done with a try..catch statement.
Here Integer is a name of a class in java.lang package and parseInt() is a method of Integer class which converts String to integer. If we want to enter a integer in a method or class using keyboard, then we have to use a method parseInt(). In this program we are going to calculate a area of a rectangle by using two classes named Rectangle and EnterValuesFromKeyboard. In the first class we have used two methods, show(int x, int y) and calculate().