CMPG 211 1-1 V 2021 Expand All Next Week 3Practical 2: Methods Main page content Methods - Week 3 Overview A method is a collection of statements grouped together to perform an operation. You have used some predefined methods in Java like System.exit, Math.pow, and Math.random. Resources Textbook: Laing, Chapter 6 Understand Java Read Par 6.1 on the purpose and example of methods Read Par 6.2 on Defining/writing a method (pp. 204 - 206) Read Par 6.3 on How to call a method (pp. 206 - 208) Practical 2: Methods Task 1Click to collapse Task 1 See the given Java source code below to enter the radius of a circle and calculate and display the area and circumference of the circle: import java.util.Scanner; public class CalcCircleMethods { public static void main(String [] args) { Scanner input = new Scanner(System.in); System.out.println("Enter the radius of a circle"); double radius = input.nextDouble(); double circumference = 2 * Math.PI * radius; double area = Math.PI * Math.pow(radius, 2); System.out.println("The radius is " + radius); System.out.printf("%s%1.1f\n", "The circumference is ", circumference); System.out.printf("%s%1.2f\n", "The area is ", area); } } Create a new Java project called CircleProject. (1.1) Create a class called staticMethods. Use the same code to calculate and display the area and circumference of a circle BUT the class must calculate and return the area and circumference of a circle using two static methods called calcArea() and calcCircumference(). The methods must receive the radius as parameter. The methods must be called from the main method. Hint: Call/invoke the methods from the main method as follows: area = calcArea(radius); circumference = calcCircumference(radius); (1.2) Object-oriented code: Create a class called testCircle and an object class called Circle. The object class Circle must contain two methods calcArea() and calcCircumference(), NOT the test class. The testCircle class must contain ONLY the main method. The main method must ask the user to enter the radius and call the methods from the object class to calculate and return the area and circumference of the circle. The main method must display the are and circumference of the circle. Hint: A Circle object must be instantiated in the test class to be able to use the methods of the object class. Use the following statement to instantiate a Circle object: Circle myCircle = new Circle(); The name of the object that you have created/instantiated is myCircle. Call the methods as follows: area = myCircle.calcArea(radius); Try to complete the tasks on your own, before watching the videos below. Task 1.1 Video Task 1.2 Video Understand Java Read Par 6.4 on void method examples (pp. 209 - 210) Answer Questions 6.1 - 6.10 (p. 211) Read Par 6.5 on Passing arguments (p. 212) Answer Questions 6.11 - 6.14 (p. 214) Read Par 6.6 on Modularizing code (p. 215) Study the two examples Read Par 6.7 Case study (p. 217) Read Par 6.8 on Overloading Methods (p. 219) Overloading methods - methods with the same name with different parameters and return types/signatures. Signature is the header of a method Example on p. 220 (Three methods with the name max) Answer Questions 6.15 - 6.17 (pp. 221 - 222) Task 2Click to collapse Task 2 Write a Java program to test for palindrome integers and strings. A number/string is a palindrome if its reversal is the same as itself. In the object class Palindrome, write the following methods: public int reverse(int number) - returns the reversal of an integer, i.e., reverse(456) will return 654 public boolean isPalindrome(int number) - return true if the number received as parameter is a palindrome. Use the reverse method to implement isPalindrome. Write a testPalindrome class that prompts the user to enter an integer and reports whether the integer is a palindrome. Example of output for input 1221: The number 1221 is a palindrome

CMPG 211 1-1 V 2021 Expand All Next Week 3Practical 2: Methods Main page content Methods - Week 3 Overview A method is a collection of statements grouped together to perform an operation. You have used some predefined methods in Java like System.exit, Math.pow, and Math.random. Resources Textbook: Laing, Chapter 6 Understand Java Read Par 6.1 on the purpose and example of methods Read Par 6.2 on Defining/writing a method (pp. 204 - 206) Read Par 6.3 on How to call a method (pp. 206 - 208) Practical 2: Methods Task 1Click to collapse Task 1 See the given Java source code below to enter the radius of a circle and calculate and display the area and circumference of the circle: import java.util.Scanner; public class CalcCircleMethods { public static void main(String [] args) { Scanner input = new Scanner(System.in); System.out.println("Enter the radius of a circle"); double radius = input.nextDouble(); double circumference = 2 * Math.PI * radius; double area = Math.PI * Math.pow(radius, 2); System.out.println("The radius is " + radius); System.out.printf("%s%1.1f\n", "The circumference is ", circumference); System.out.printf("%s%1.2f\n", "The area is ", area); } } Create a new Java project called CircleProject. (1.1) Create a class called staticMethods. Use the same code to calculate and display the area and circumference of a circle BUT the class must calculate and return the area and circumference of a circle using two static methods called calcArea() and calcCircumference(). The methods must receive the radius as parameter. The methods must be called from the main method. Hint: Call/invoke the methods from the main method as follows: area = calcArea(radius); circumference = calcCircumference(radius); (1.2) Object-oriented code: Create a class called testCircle and an object class called Circle. The object class Circle must contain two methods calcArea() and calcCircumference(), NOT the test class. The testCircle class must contain ONLY the main method. The main method must ask the user to enter the radius and call the methods from the object class to calculate and return the area and circumference of the circle. The main method must display the are and circumference of the circle. Hint: A Circle object must be instantiated in the test class to be able to use the methods of the object class. Use the following statement to instantiate a Circle object: Circle myCircle = new Circle(); The name of the object that you have created/instantiated is myCircle. Call the methods as follows: area = myCircle.calcArea(radius); Try to complete the tasks on your own, before watching the videos below. Task 1.1 Video Task 1.2 Video Understand Java Read Par 6.4 on void method examples (pp. 209 - 210) Answer Questions 6.1 - 6.10 (p. 211) Read Par 6.5 on Passing arguments (p. 212) Answer Questions 6.11 - 6.14 (p. 214) Read Par 6.6 on Modularizing code (p. 215) Study the two examples Read Par 6.7 Case study (p. 217) Read Par 6.8 on Overloading Methods (p. 219) Overloading methods - methods with the same name with different parameters and return types/signatures. Signature is the header of a method Example on p. 220 (Three methods with the name max) Answer Questions 6.15 - 6.17 (pp. 221 - 222) Task 2Click to collapse Task 2 Write a Java program to test for palindrome integers and strings. A number/string is a palindrome if its reversal is the same as itself. In the object class Palindrome, write the following methods: public int reverse(int number) - returns the reversal of an integer, i.e., reverse(456) will return 654 public boolean isPalindrome(int number) - return true if the number received as parameter is a palindrome. Use the reverse method to implement isPalindrome. Write a testPalindrome class that prompts the user to enter an integer and reports whether the integer is a palindrome. Example of output for input 1221: The number 1221 is a palindrome

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Main page content

Methods - Week 3

Overview

A method is a collection of statements grouped together to perform an operation. You have used some predefined methods in Java like System.exit, Math.pow, and Math.random.

Resources

Textbook: Laing, Chapter 6

Understand Java

Read Par 6.1 on the purpose and example of methods
Read Par 6.2 on Defining/writing a method (pp. 204 - 206)

Read Par 6.3 on How to call a method (pp. 206 - 208)

Practical 2: Methods

Task 1Click to collapse

Task 1

See the given Java source code below to enter the radius of a circle and calculate and display the area and circumference of the circle:

import java.util.Scanner;
public class CalcCircleMethods
{
public static void main(String [] args)
{
Scanner input = new Scanner(System.in);

System.out.println("Enter the radius of a circle");
double radius = input.nextDouble();

double circumference = 2 * Math.PI * radius;
double area = Math.PI * Math.pow(radius, 2);

System.out.println("The radius is " + radius);

System.out.printf("%s%1.1f\n", "The circumference is ", circumference);
System.out.printf("%s%1.2f\n", "The area is ", area);
}
}

Create a new Java project called CircleProject.

(1.1) Create a class called staticMethods. Use the same code to calculate and display the area and circumference of a circle BUT the class must calculate and return the area and circumference of a circle using two static methods called calcArea() and calcCircumference(). The methods must receive the radius as parameter.

The methods must be called from the main method.

Hint: Call/invoke the methods from the main method as follows:

area = calcArea(radius);

circumference = calcCircumference(radius);

(1.2) Object-oriented code:

Create a class called testCircle and an object class called Circle.

The object class Circle must contain two methods calcArea() and calcCircumference(), NOT the test class.

The testCircle class must contain ONLY the main method. The main method must ask the user to enter the radius and call the methods from the object class to calculate and return the area and circumference of the circle. The main method must display the are and circumference of the circle.

Hint:

A Circle object must be instantiated in the test class to be able to use the methods of the object class. Use the following statement to instantiate a Circle object:

Circle myCircle = new Circle();

The name of the object that you have created/instantiated is myCircle.

Call the methods as follows:

area = myCircle.calcArea(radius);

Try to complete the tasks on your own, before watching the videos below.

Task 1.1 Video

Task 1.2 Video

Understand Java

Read Par 6.4 on void method examples (pp. 209 - 210)
- Answer Questions 6.1 - 6.10 (p. 211)
Read Par 6.5 on Passing arguments (p. 212)
- Answer Questions 6.11 - 6.14 (p. 214)
Read Par 6.6 on Modularizing code (p. 215)
- Study the two examples
Read Par 6.7 Case study (p. 217)
Read Par 6.8 on Overloading Methods (p. 219)
- Overloading methods - methods with the same name with different parameters and return types/signatures.
- Signature is the header of a method
- Example on p. 220 (Three methods with the name max)
- Answer Questions 6.15 - 6.17 (pp. 221 - 222)

Task 2Click to collapse

Task 2

Write a Java program to test for palindrome integers and strings.

A number/string is a palindrome if its reversal is the same as itself.

In the object class Palindrome, write the following methods:

public int reverse(int number) - returns the reversal of an integer, i.e., reverse(456) will return 654
public boolean isPalindrome(int number) - return true if the number received as parameter is a palindrome. Use the reverse method to implement isPalindrome.

Write a testPalindrome class that prompts the user to enter an integer and reports whether the integer is a palindrome.

Example of output for input 1221:

The number 1221 is a palindrome

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