CS141 HW Quiz 1, Java

How to create a class in java

Ex: Create a shape class

class Shape {
…
}

How to create a class that you don’t want to be able to be made into an object in Java

Ex: Create a shape class

abstract class Shape {
…
}

How to create a pure virtual member function in a class in Java
ex: a area class of type double

abstract double area();

Create a Circle class that inherits from shape.
Create the data members radius and PI, radius is a double, pi is a double constant with a value of 3.14
Write a constructor to initialize radius
Create a member function area of type double that returns the area of a circle

class Circle extends Shape{

double radius;
static final double PI = 3.14;

Circle(double radius){
super();
this.radius = radius;
}
double area(){
return(this.radius*this.radius*Cthis.PI);
}

Create the main function/class in java

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

Create an array of shape objects of set size 2

Shape[] shapeArray = new Shape[2];

Create an array of shape objects, fill the shape with two circles

Shape []shape Array = new Shape[]{new Circle(2), new Circle(5)};

How to convert double to string

Double.toString(postDoubleHere);H

How to print a line (remember, you can only print strings)

System.out.println(“what u need to print here”);

Print shapes area in a shape array

for(int i = 0; i<2; i++){
System.out.println(Double.toString(shapeArray[i].area());
}H

How to assign something null in Java

head = null;

How to convert string to int in java

int x = Integer.parseInt(string);

How to convert int to string in java

string y = Integer.toString(x);