Module# 02: Generic Programming Lecture#03: Generic Class Basics

// Example 3.1: Program to handle an array of integers

class SpecificArrayInt {

// Declaring an array of integer numbers

int a;

// Constructor to load the array

SpecificArrayInt(int a[]) {

this.a = a;

}

// Method to print the array elements

void printInt() {

for(int x : a)

System.out.println(x);

}

// Method to reverse the array elements

void reverseInt() {

j = a.length;

for (int i=0; i<j; i++)

int temp;

temp = a[i];

a[i] = a[j];

a[j] = temp;

j--;

} // End of for-loop

} // end of method

} // end of class

class MainClassInt {

//This class use the class SpecificArrayInt to manipulate data in it

SpecificArrayInt a = {1, 2, 3, 4, 5};

a.printInt();

a.reverseInt();

a.printInt();

}

// Example 3.2: Program to handle an array of doubles

class SpecificArrayDouble {

// Declaring an array of double values

double b;

// Constructor to load the array

SpecificArrayDouble(double b[]) {

this.b = b;

}

// Method to print the array elements

void printDouble() {

for(double x : b)

System.out.println(x);

}

// Method to reverse the array elements

void reverseDouble() {

j = b.length;

for (int i=0; i<j; i++)

double temp;

temp = a[i];

a[i] = a[j];

a[j] = temp;

j--;

} // End of for-loop

} // end of method

} // end of class

class MainClassDouble {

//This class use the class SpecificArrayInt to manipulate data in it

SpecificArrayDouble b = {1.2, 2.3, 3.4, 4.5, 5.6};

b.printDouble();

b.reverseDouble();

b.printDouble();

}

// Example 3.3: Program to handle an array of Strings

class SpecificArrayString {

// Declaring an array of double values

String c;

// Constructor to load the array

SpecificArrayDouble(String c[]) {

this.c = c;

}

// Method to print the array elements

void printString() {

for(String x : c)

System.out.println(x);

}

// Method to reverse the array elements

void reverseString() {

j = c.length;

for (int i=0; i<j; i++)

double temp;

temp = c[i];

c[i] = c[j];

c[j] = temp;

j--;

} // End of for-loop

} // end of method

} // end of class

class MainClassString {

//This class use the class SpecificArrayInt to manipulate data in it

SpecificArrayDouble b = {“A”, “B”, “C”, “D”, “E”};

c.printString();

c.reverseString();

c.printString();

}

// Example 3.4: Defining a generic class

public class GeneriClass <T> {

// Two elemnts of generic type T is defined below

private T x;

// Constructor

public GenericClass(T t) {

x = t;

}

// Print the T-type value for an object

public void printData() {

System.out.println (x);

}

} // This completes the definition of a simple generic class GeneriClass<T>

// The driver class is defined below, which creates different types of arrays.

class GenericClassTest {

public static void main( String args[] ) {

// A data with the member as String

GenericClass<String> a = new GenericClass<String> ("Java");

a.printData();

// A data with the member as integer value

GenericClass<Integer> b = new GenericClass<Integer> (123);

b.printData();

// A data with the member as float value

GenericClass<Double> c = new GenericClass<Double> (3.142);

c.printData();

}

}

// Example 3.5: Defining a generic class to process arrays with any data types

class GenericArray<T> {

//Declaring an array, which should store any type T of data

T a[ ];

GenericArray(T x) { // Define a constructor

a = x;

}

T getData(int i) { // To return the element stored in the i-th place in the array

return a[i];

}

void static printData (T b) { // A generic method to print the elements in array b

for(int i = 0; i < b.length(); i ++)

System.out.print(b.getData(i) + “ “); // Print the i-th element in b

System.out.println(); // Print a new line

}

// Generic method to reversed the order of elements in array b

void static reverseArray (T b) {

int front = 0, rear = b.length-1;

T temp;

while( front < rear) {

temp = b[rear];

b[rear] = a[front];

a[front] = temp;

front++; rear--;

}

}

}