Question

This project involves writing a program with functionality of your choosing. You must include the programming elements as described below and must adhere to the general requirements below.

Programming elements: The code must contain the following elements:

(You may complete one program containing all of these elements or you may submit more than one program where all program together contain the following elements.)

Classes (at least 3)

Instance Fields and Methods

Constructors

Overloaded Method/Constructor (at least one)

Arrays / ArrayLists (at least one)

Parameter passing (at least one object passed as an argument)

Use of the toString method (for one of your objects)

Use of the equals method (for one of your objects)

Use of two Character Class methods (isDigit, isLetter, isLetterorDigit, is LowerCase, isUpperCase, is SpaceChar, toLowerCase, toUpperCase, …)

Use of two String methods (indexOf, lastIndexOf, getChars, toCharArray, Concat, replace, trim, …)

Inheritance (at least one use)

Exception Handling (at least one try-catch block)

Use of GUI Components (at least two: buttons, labels, text fields, checkboxes, radio buttons, combo boxes, sliders)

Note: You may complete one program containing all of these elements or you may submit more than one program where all program together contain the following elements.

General requirements:

No compile or runtime errors

Code is commented and documented (functionality of entire program is adequately described as well as methods are adequately described)

Answer 1

//program  1

import java.util.ArrayList;

class Shape2D {
    //instance fields
    int len, width;

    //constructor
    Shape2D() {
        len = width = 0;
    }

    //constructor overloading
    public Shape2D(int len, int width) {
        this.len = len;
        this.width = width;
    }

    //instance methods
    public int getLen() {
        return len;
    }

    public void setLen(int len) {
        this.len = len;
    }

    public int getWidth() {
        return width;
    }

    public void setWidth(int width) {
        this.width = width;
    }

    void printArea() {
        System.out.println("Area = " + this.len * this.width);
    }

}

//class Shape3D inherits from class Shape2D
class Shape3D extends Shape2D {
    //instance fields
    int height;

    {
        //this blocks gets called before the constructor
        System.out.println("\nInitialising instance variables with default values...");
        this.len = 0;
        this.width = 0;
        this.height = 0;
        System.out.println("len = " + len + " wid = " + width + " height = " + height);
    }

    //constructor
    public Shape3D() {
    }

    //constructor overloading
    public Shape3D(int len, int width, int height) {
        System.out.println("Constructor called.");
        this.len = len;
        this.width = width;
        this.height = height;
        System.out.println("len = " + len + " wid = " + width + " height = " + height);
    }

    //constructor overloading
    public Shape3D(int a) {
        System.out.println("Constructor called.");
        this.len = a;
        this.width = a;
        this.height = a;
        System.out.println("len = " + len + " wid = " + width + " height = " + height);
    }

    //instance methods
    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }

    void printVol() {
        System.out.println("Volume = " + this.len * this.width * this.height);
    }

}


class MyJavaTutorial {

    //this method can throw ArithmeticException so function call must be surrounded with try catch block
    private static int divideAbyB(int a, int b) throws ArithmeticException {
        return a / b;
    }

    private static void checkIfStringsAreEqual(String s1, String s2) {
        //using the equals method
        if (s1.equals(s2)) {
            System.out.println("Both the strings are matching.");
        } else {
            System.out.println("The strings are not matching.");
        }
    }

    //this method uses Character class methods
    private static boolean isStringLowerCase(String str) {

        //converts the String to char array
        char[] charArray = str.toCharArray();

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

            //checks if the character is a letter
            if (Character.isLetter(charArray[i])) {

                //if any character is not in lower case, return false
                if (!Character.isLowerCase(charArray[i]))
                    return false;
            }
        }

        return true;

    }

    //takes an object of Shape3D class as parameter
    private static void printCuboidOrCube(Shape3D shape3D) {
        if (shape3D.getWidth() == shape3D.getLen() && shape3D.getLen() == shape3D.getHeight()) {
            System.out.println("\nIt\'s a cube.");
        } else {
            System.out.println("\nIt\'s a cuboid.");
        }
    }

    public static void main(String[] args) {

        Shape3D cuboid = new Shape3D(4, 5, 6);
        Shape3D cube = new Shape3D(4);

        //creating an arraylist of  Shape3D objects
        ArrayList<Shape3D> shape3DArrayList = new ArrayList<>();
        shape3DArrayList.add(cuboid);
        shape3DArrayList.add(cube);

        for (Shape3D shape3D : shape3DArrayList) {
            printCuboidOrCube(shape3D);
            shape3D.printArea();
            shape3D.printVol();
        }
        System.out.println();

        String s1 = "Pet";
        String s2 = " is sleeping";
        String s3 = "Pet";
        checkIfStringsAreEqual(s1, s2);
        checkIfStringsAreEqual(s1, s3);
        System.out.println();

        //using String class methods...
        System.out.println(s1.indexOf('e') + "\n");    //prints the index of 'e' in string s1
        String s4 = "My pet dog Tommy";
        s4 = s4.concat(s2);     //using concatenation method
        System.out.println(s4 + "\n");
        s3 = s3.toLowerCase();  //converting the string to lower case
        System.out.println(s3);

        if (isStringLowerCase(s2)) {
            System.out.println("\nString \'" + s2 + "\' is in lower case.");
        } else {
            System.out.println("\nString \'" + s2 + "\' is not in lower case.");
        }


        System.out.println();
        //Exception Handling
        int a = 8;
        int b = 0;
        try {
            int c = divideAbyB(a, b);
            System.out.println(c);
        } catch (Exception e) {
            System.out.println(e.toString());
        }

    }

}

//output screenshot for this program : 

//program 2 using gui components

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

class MyGui{
    public static void main(String args[]){

        JFrame frame = new JFrame("My frame");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        //labels
        Label l1 = new Label("First :");
        Label l2 = new Label("Second :");

        //TextFields
        TextField t1 = new TextField(10);
        TextField t2 = new TextField(10);

        //Button
        Button button = new Button("OK");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                //swapping the contents of the two textfields on click of the button
                String text1 = t1.getText().trim();
                String text2 = t2.getText().trim();
                t1.setText(text2);
                t2.setText(text1);
            }
        });

        //adding the components to the frame
        frame.add(l1);
        frame.add(t1);
        frame.add(l2);
        frame.add(t2);
        frame.add(button);

        frame.setLayout(new FlowLayout());
        frame.setSize(350, 350);
        frame.setVisible(true);
    }
}

//output of program 2