Question

Circle
Radius: double
Circle()
Circle(newRadius: double)
getArea(): double
setRadius(newRadius: double): void
getRadius(): double

After creating the Circle class, you should test this class from the main() method by passing objects of this
class to a method “ public static void printAreas(Circle c, int times)”
You should display the area of the circle object 5 times with different radii.

2

java.util.Random
+Random()
+Random(seed: long)
+nextInt(): int
+nextInt(n: int): int
+nextLong(): long
+nextDouble(): double
+nextFloat(): float
+nextBoolean(): boolean

Constructs a Random object with the current time as its seed.
Constructs a Random object with a specified seed.
Returns a random int value.
Returns a random int value between 0 and n (exclusive).
Returns a random long value.
Returns a random double value between 0.0 and 1.0 (exclusive).
Returns a random float value between 0.0F and 1.0F (exclusive).
Returns a random boolean value.

Using this class, do the following:
1. Generate and display 20 random numbers of type integer in the range 0 to 50.
2. Generate and display 20 random numbers of type integer with seed 3 in the range 0 to 1000.
3. Generate and display 20 random numbers of type double in the range 10 to 50.

3

java.util.Date
+Date()
+Date(elapseTime: long)
+toString(): String
+getTime(): long
+setTime(elapseTime: long): void

Constructs a Date object for the current time.
Constructs a Date object for a given time in
milliseconds elapsed since January 1, 1970, GMT.
Returns a string representing the date and time.
Returns the number of milliseconds since January 1,
1970, GMT.
Sets a new elapse time in the object.

The + sign indicates
public modifer

Using this class, display the current time.

Answer 1

Find the java code below. Comments are provided throughout the code.

Circle class

public class Circle {
        
        private double radius;
        
        public Circle() {
        }

        public Circle(double newRadius) {
                this.radius = newRadius;
        }
        
        public double getArea() {
                return Math.PI * radius * radius;
        }

        public double getRadius() {
                return radius;
        }

        public void setRadius(double newRadius) {
                this.radius = newRadius;
        }
}

Main Method - all 3 questions here

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;

public class Main {
        
        public static void main(String[] args) {
                
                /*
                 * Question 1
                 */
                
                // print are 5 times
                Circle c = new Circle();
                printAreas(c, 5);
                
                /*
                 * Question 2
                 */
                
                // 1. Generate and display 20 random numbers of type integer in the range 0 to 50.
                
                Random r1 = new Random();
                
                for(int i = 0; i < 20; i++) {
                        System.out.print(r1.nextInt(50) + " ");
                }
                System.out.println();
                
                // 2. Generate and display 20 random numbers of type integer with seed 3 in the range 0 to 1000.
                
                Random r2 = new Random(3);
                
                for(int i = 0; i < 20; i++) {
                        System.out.print(r2.nextInt(1000) + " ");
                }
                System.out.println();
                
                // 3. Generate and display 20 random numbers of type double in the range 10 to 50.
        
                for(int i = 0; i < 20; i++) {
                        System.out.print(10 + r1.nextDouble() * 40 + " ");
                }
                System.out.println();
        
                /*
                 * Question 3
                 */
                
                // 1. Display the current time.
                
                Date date = new Date();
                
                // this method display the date also
                System.out.println(date.toString());
                
                // to display only time, use simpleDateFormat
                SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss a");
                
                System.out.println(dateFormat.format(date));
                
                
        }
        
        public static void printAreas(Circle c, int times) {
                
                Random r = new Random();
                
                for (int i = 0; i < times; i++) {
                        
                        // set a random radius
                        c.setRadius(r.nextDouble() * 10);
                        
                        // print area
                        System.out.println(c.getArea());
                }
        }

}

Kindly upvote.