InputEvent's modifiers are stored as an int value.
Each bit in the int is a flag corresponding to a particular modifier.
The corresponding values for 
these flags are given as public final static ints in the InputEvent class: 
You can retrieve the modifiers for an event with the 
    
getModifiers() method:
public int getModifiers()
Use the bitwise & operator to test whether a particular flag is set.
For example,
if (e.getModifiers() & InputEvent.BUTTON2_MASK != 0) {
  System.out.println("Button 2 was pressed");
}