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evenlybytheloopindex.Forexample,because 6/2 yieldsaremainderof0
(2 divides evenly into 6), integer 6 is not a prime number.
2. Reflection is useful in a device driver context, where an application needs
the application invokes its methods. If a newer version is detected, the ap-
plication can invoke the older methods or invoke newer versions of those
methods.Createtwoversionsofa Driver class.Thefirstversiondeclares
a String getCapabilities() method that returns " basic cap-
abilities ", and the second version declares this method along with a
String getCapabilitiesEx() method that returns " extended
capabilities ".Createa DriverDemo classthatusesreflectiontode-
termine if the current Driver.class classfile supports getCapabil-
itiesEx() ,andinvokethatmethodifitdoes.Ifthemethoddoesnotex-
ist, use reflection to determine if it supports getCapabilities() , and
invoke that method if that is the case. Otherwise, output an error message.
3. Javaarrayshavefixedlengths.Createagrowablearrayclass, GArray<E> ,
mentpassedto E .Thisclassdeclaresa GArray(int initCapacity)
fiedby initCapacity .Also,thisclassdeclares E get(int index)
and void set(int index, E value) methods that respectively
return the object at the index position within the internal array, and store
the specified value in the array at the index position. The get() meth-
odmustthrow ArrayIndexOutOfBoundsException whentheargu-
mentpassedto index isoutofrange(negativeorgreaterthan/equaltothe
array's length). The set() method must throw the same exception when
the argument passed to index is negative. However, when the argument
is positive, it must create a new internal array whose size is twice that of
the old array, copy elements from the old array to the new array via Sys-
tem.arraycopy() ,andstorethenewvalueatthe index position.This
class also declares an int size() method that returns the array's size.
Testthisclasswiththe GArrayDemo applicationdescribedin Listing4-34 .
Listing 4-34. Demonstrating a growable array
import ca.tutortutor.collections.GArray;
class GArrayDemo
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