Write ONE application program (ONE MAIN METHOD) by using the following requirements:
File input and output (10 points)
Exception handling (10 points)
You can create your own exception classes or
You can use existing exception classes from Java API
Inheritance
At least one superclass or abstract superclass: this class needs to have data members, accessor, mutator, and toString methods (10 points)
At least one subclass: this class also needs to have data members, accessor, mutator, and toString methods (10 points)
At least one interface: this interface needs to have at least two abstract methods (10 points)
At least one method overloading (10 points)
At least one method overriding (10 points)
At least one static member and one static method (10 points)
Polymorphism: you need to have at least one superclass reference to reference objects of a subclass (10 points)
At least one aggregation in a class (10 points)
Within your project, PLEASE include comments at the place where you use the above items. I will deduct the points if I cannot find the above items within your project.
Answer:
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
//inheritance.
//below is my super class.
class Numbers {
//class Numbers data members
protected Integer myint;
protected Double mydouble;
// Numbers class mutators
public void setInteger(Integer i) {
this.myint = i;
i.toString(); // use of toString Method
}
public void setDouble(Double j) {
this.mydouble = j;
j.toString(); //use of toString method
}
// Numbers class accessors
public Integer getInteger() {
return myint;
}
public Double getDouble() {
return mydouble;
}
}
//MyInteger class which is sub-class of Numbers
class MyInteger extends Numbers {
//data members
protected Integer a;
//mutator method
public void setMyint(Integer b) {
this.a = b;
a.toString(); // toString Method
}
//Accessor method
public Integer getMyint() {
return a;
}
}
//Double class which is sub-class of Numbers
class MyDouble extends Numbers {
//data members
protected Double c;
//mutator method
public void setMydouble(Double d) {
this.c = d;
c.toString(); // toString Method
}
//Accessor method
public Double getMydouble() {
return c;
}
}
//use of interfaces
interface Insect {
//abstract methods of insect interface
public void insectMovement(); // abstract method of inteface has no body
public void insectInhabitat();
}
//a class to implement our interface
class Grasshopper implements Insect {
//method overriding
static String s = "Jumps"; // static member
static String i = "Thickets"; //static member
@Override
public void insectMovement() {
System.out.println(s); //standard output
}
//method overriding
@Override
public void insectInhabitat() {
System.out.println(i); //standard output
}
}
//use of aggregation in a class
class Operate {
double square(double m) {
return m * m;
}
}
class Circle {
Operate op;//class aggregation
double db;
double area(double radius) {
//Exception handling using try catch block.
try {
op = new Operate();
db = op.square(radius);
} catch (Exception e) {
e.printStackTrace();
}
return Math.PI * db;
}
}
//use of polymorphism and method overloading.
//animalSound method is used in different ways thus polymorphism.
//have used static methods here
class Animal {
public static String animalSound() { //static method in super class
return "This is animal sound:";
}
}
class Donkey extends Animal {
public static String animalSound(String s) { //static method in sub-class Donkey
return s;
}
}
class Dog extends Animal {
public static String animalSound(String f) { // static method in Dog class
return f;
}
}
//use File I/O
class FileIO {
public String writeToFile(String s) {
//file output, writing to a file
return s;
}
//file input, reading a file
public String readFile(String contents) {
return contents;
}
}
public class MyProgram {
public static void main(String args[]) throws IOException {
//create object of class MyInteger and try to access members of super class Numbers
System.out.println("Sample output for inheritance class:");
MyInteger num1 = new MyInteger();
Scanner int1 = new Scanner(System.in);
System.out.println("Enter a Number:");
Integer num = int1.nextInt();
num1.setInteger(num);
System.out.println("You entered:" + num1.getInteger());
//test aggregation output
System.out.println("Printing area of circle in aggregation:");
Circle c = new Circle();
Scanner radius = new Scanner(System.in);
System.out.println("Enter Circle radius:");
Double d = radius.nextDouble();
System.out.println("Area is:" + c.area(d));
//test polymorphism
System.out.println("Printing animal sounds using polymorphism:");
Donkey dh = new Donkey();
Dog dg = new Dog();
Animal a = new Animal();
System.out.println("What sound is produced by a Dog? Enter sound Below:");
Scanner sound = new Scanner(System.in);
String sd = sound.nextLine();
System.out.println(a.animalSound());
System.out.println("A Dog:" + dg.animalSound(sd));
System.out.println("What sound is produced by a Donkey? Enter sound Below:");
Scanner sound2 = new Scanner(System.in);
String sd2 = sound2.nextLine();
System.out.println(a.animalSound());
System.out.println("A Donkey:" + dh.animalSound(sd2));
// test File input/output
System.out.println("This is File I/O:");
FileIO file = new FileIO();
Scanner file1 = new Scanner(System.in);
System.out.println("Enter name of file to write: e.g myfile.txt");
String filename = file1.nextLine();
FileOutputStream fout;
try {
fout = new FileOutputStream(file.writeToFile(filename));
Scanner filecontent = new Scanner(System.in);
System.out.println("Enter what you want to write in the file:");
String s = filecontent.nextLine();
byte b[] = s.getBytes();//converting string into byte array
fout.write(b);
fout.close();
System.out.println("success...");
} catch (Exception e) {
System.out.println(e);
}
//read file created
FileInputStream fin = null;
try {
fin = new FileInputStream(filename);
} catch (FileNotFoundException ex) {
Logger.getLogger(MyProgram.class.getName()).log(Level.SEVERE, null, ex);
}
int i = 0;
System.out.println("File content is:");
while ((i = fin.read()) != -1) {
System.out.print((char) i);
}
System.out.println();
fin.close();
}
}
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