Question

1) Using the Quadratic class you have already developed, make it Comparable. A Quadratic is bigger than another Quadratic if it opens faster.

2) Write a driver for Quadratic.java. In the driver program create a few objects and compare them . then create a list of those objects and sort them.

import java.util.*;
import java.lang.*;

class Quadratic{

   private double a,b,c; // Determines/declares the class variables to store the coefficients

       Quadratic(){ // Determine/declare the default constructor

           a=0.0;
           b=0.0;
           c=0.0;
       }

       Quadratic(double a, double b, double c){ // Parametrized constructor

           this.a=a;
           this.b=b;
           this.c=c;
       }

       public void setCoefs(double a, double b, double c){ // Mutator method

           this.a=a;
           this.b=b;
           this.c=c;
       }

       public double getA(){
           return a;
       }

       public double getB(){

           return b;
       }

       public double getC(){

           return c;
       }

       public double getDisc(){ // Determine discriminant

           return (b*b)-(4*a*c);
       }

       public void natureOfRoots(){ // Method that prints nature of roots

           if(getDisc()<0.0)

           System.out.println("complex roots.");
               else if(getDisc()==0.0)
           System.out.println("real and equal roots.");
               else
           System.out.println("real roots.");
       }

       public double getDeriv(double x){ // Method that gets the value of first order derivative at a point

           return (2*a*x)+b; // Differentiating ax^2+bx+c gives us 2ax+b
       }

       public String toString(){ // Method that converts the object of this class to string for printing

           String s;

           if(a==1.0)
               s="x^2";
           else
               s=a+"x^2";
           if(b<0.0)
               s=s+b+"x";
           else if(b==1.0)
               s=s+"+x";
           else
               s=s+"+"+b+"x";
           if(c<0.0)
               s=s+c;
           else
               s=s+"+"+c;
           return s;
       }

       public void printRoots(){ // Method that prints roots

           if(getDisc()<0.0)
   {
       System.out.println("The roots are imaginary!");
       return;
   }

       double qua1=(-b+Math.sqrt(getDisc()))/(2*a);
       double qua2=(-b-Math.sqrt(getDisc()))/(2*a);
       System.out.println("The roots are " + qua1 + " & " + qua2 + ".");
   }
}

   class TestQuadratic{ // Test the class

       public static void main(String args[]){

           Quadratic quad1=new Quadratic(1, -2, 1); // Creating object of the Quadratic class

           System.out.print("The Equation is: " + quad1 + " which has "); // Print the equation

           quad1.natureOfRoots();   // Print the nature of roots
           quad1.printRoots();      // Print the roots
           // quad.setCoefs(1,3,2);   // Chang the coefficients using mutator method
       
         Quadratic quad2 = new Quadratic(1, 3, 2); // Creating the second object of the Quadratic class

           System.out.print("\nThe Equation (Second Quadratic) after changing the coefficients is: " + quad2 + " which has "); // Print the equation

           quad2.natureOfRoots();   // Print the nature of the roots
         quad2.printRoots();      // Print the roots... again
   }
}

Answer 1

//////////////////////   Quadratic.java

public class Quadratic implements Comparable<Quadratic>{

private double a,b,c; // Determines/declares the class variables to store the coefficients

Quadratic(){ // Determine/declare the default constructor

a=0.0;
b=0.0;
c=0.0;
}

Quadratic(double a, double b, double c){ // Parametrized constructor

this.a=a;
this.b=b;
this.c=c;
}

public void setCoefs(double a, double b, double c){ // Mutator method

this.a=a;
this.b=b;
this.c=c;
}

public double getA(){
return a;
}

public double getB(){

return b;
}

public double getC(){

return c;
}

public double getDisc(){ // Determine discriminant

return (b*b)-(4*a*c);
}

public void natureOfRoots(){ // Method that prints nature of roots

if(getDisc()<0.0)

System.out.println("complex roots.");
else if(getDisc()==0.0)
System.out.println("real and equal roots.");
else
System.out.println("real roots.");
}

public double getDeriv(double x){ // Method that gets the value of first order derivative at a point

return (2*a*x)+b; // Differentiating ax^2+bx+c gives us 2ax+b
}

public String toString(){ // Method that converts the object of this class to string for printing

String s;

if(a==1.0)
s="x^2";
else
s=a+"x^2";
if(b<0.0)
s=s+b+"x";
else if(b==1.0)
s=s+"+x";
else
s=s+"+"+b+"x";
if(c<0.0)
s=s+c;
else
s=s+"+"+c;
return s;
}

public void printRoots(){ // Method that prints roots

if(getDisc()<0.0)
{
System.out.println("The roots are imaginary!");
return;
}

double qua1=(-b+Math.sqrt(getDisc()))/(2*a);
double qua2=(-b-Math.sqrt(getDisc()))/(2*a);
System.out.println("The roots are " + qua1 + " & " + qua2 + ".");
}

@Override
public int compareTo(Quadratic o) {
  
int ret=0;
  
double a1=a,b1=b,c1=c;
double a2=o.getA(),b2=o.getB(),c2=o.getC();
  
// first check a1>a2 if equal
// then b1>b2 if equal
// then c>c2 if equal retun 0
  
if(a1<a2){
ret=1;
}
else{
if(a1>a2){
ret=-1;
}else{
if(b1<b2){
ret=1;
}
else{
if(b1>b2){
ret=-1;
}
else{
if(c1<c2){ret=1;}
if(c1>c2){ret=-1;}
}
}
}
}
  
return(ret);

}
}

/////////////////////////// TestQuadratic.java

public class TestQuadratic {

  
public static void main(String args[]){

Quadratic quad1=new Quadratic(1, -2, 1); // Creating object of the Quadratic class

System.out.print("The Equation is: " + quad1 + " which has "); // Print the equation

quad1.natureOfRoots(); // Print the nature of roots
quad1.printRoots(); // Print the roots
// quad.setCoefs(1,3,2); // Chang the coefficients using mutator method

Quadratic quad2 = new Quadratic(1, 3, 2); // Creating the second object of the Quadratic class

System.out.print("\nThe Equation (Second Quadratic) after changing the coefficients is: " + quad2 + " which has "); // Print the equation

quad2.natureOfRoots(); // Print the nature of the roots
quad2.printRoots(); // Print the roots... again


// Creating the test object of the Quadratic class

Quadratic testquad1 = new Quadratic(1.2, 3.8, 2);
Quadratic testquad2 = new Quadratic(2.4, 7.6, 4);
Quadratic testquad3 = new Quadratic(6, 4, 11);
Quadratic testquad4 = new Quadratic(3, 3.1, 5);
Quadratic testquad5 = new Quadratic(6, 11, -2);
Quadratic testquad6 = new Quadratic(1, 4, 2);
Quadratic testquad7 = new Quadratic(3, 13, 5);
Quadratic testquad8 = new Quadratic(2, 8, 4);

// print each Quadratic

System.out.print("\nTestQuad1 : "+testquad1);
System.out.print("\nTestQuad2 : "+testquad2);
System.out.print("\nTestQuad3 : "+testquad3);
System.out.print("\nTestQuad4 : "+testquad4);
System.out.print("\nTestQuad5 : "+testquad5);
System.out.print("\nTestQuad6 : "+testquad6);
System.out.print("\nTestQuad7 : "+testquad7);
System.out.print("\nTestQuad8 : "+testquad8);

System.out.println();
System.out.println();

// testing

if(testquad1.compareTo(testquad2)>0){System.out.println("TestQuad1 > TestQuad2");}
if(testquad1.compareTo(testquad2)<0){System.out.println("TestQuad1 < TestQuad2");}
if(testquad1.compareTo(testquad2)==0){System.out.println("TestQuad1 == TestQuad2");}


if(testquad2.compareTo(testquad3)>0){System.out.println("TestQuad2 > TestQuad3");}
if(testquad2.compareTo(testquad3)<0){System.out.println("TestQuad2 < TestQuad3");}
if(testquad2.compareTo(testquad3)==0){System.out.println("TestQuad2 == TestQuad3");}


if(testquad4.compareTo(testquad5)>0){System.out.println("TestQuad4 > TestQuad5");}
if(testquad4.compareTo(testquad5)<0){System.out.println("TestQuad4 < TestQuad5");}
if(testquad4.compareTo(testquad5)==0){System.out.println("TestQuad4 == TestQuad5");}


if(testquad6.compareTo(testquad8)>0){System.out.println("TestQuad6 > TestQuad8");}
if(testquad6.compareTo(testquad8)<0){System.out.println("TestQuad6 < TestQuad8");}
if(testquad6.compareTo(testquad8)==0){System.out.println("TestQuad6 == TestQuad8");}


if(testquad5.compareTo(testquad7)>0){System.out.println("TestQuad5 > TestQuad7");}
if(testquad5.compareTo(testquad7)<0){System.out.println("TestQuad5 < TestQuad7");}
if(testquad5.compareTo(testquad7)==0){System.out.println("TestQuad5 == TestQuad7");}


if(testquad3.compareTo(testquad4)>0){System.out.println("TestQuad3 > TestQuad4");}
if(testquad3.compareTo(testquad4)<0){System.out.println("TestQuad3 < TestQuad4");}
if(testquad3.compareTo(testquad4)==0){System.out.println("TestQuad3 == TestQuad4");}


if(testquad1.compareTo(testquad8)>0){System.out.println("TestQuad1 > TestQuad8");}
if(testquad1.compareTo(testquad8)<0){System.out.println("TestQuad1 < TestQuad8");}
if(testquad1.compareTo(testquad8)==0){System.out.println("TestQuad1 == TestQuad8");}


if(testquad8.compareTo(testquad3)>0){System.out.println("TestQuad8 > TestQuad3");}
if(testquad8.compareTo(testquad3)<0){System.out.println("TestQuad8 < TestQuad3");}
if(testquad8.compareTo(testquad3)==0){System.out.println("TestQuad8 == TestQuad3");}


if(testquad5.compareTo(testquad4)>0){System.out.println("TestQuad5 > TestQuad4");}
if(testquad5.compareTo(testquad4)<0){System.out.println("TestQuad5 < TestQuad4");}
if(testquad5.compareTo(testquad4)==0){System.out.println("TestQuad5 == TestQuad4");}


if(testquad6.compareTo(testquad2)>0){System.out.println("TestQuad6 > TestQuad2");}
if(testquad6.compareTo(testquad2)<0){System.out.println("TestQuad6 < TestQuad2");}
if(testquad6.compareTo(testquad2)==0){System.out.println("TestQuad6 == TestQuad2");}


if(testquad3.compareTo(testquad7)>0){System.out.println("TestQuad3 > TestQuad7");}
if(testquad3.compareTo(testquad7)<0){System.out.println("TestQuad3 < TestQuad7");}
if(testquad3.compareTo(testquad7)==0){System.out.println("TestQuad3 == TestQuad7");}

// Quadratic array

Quadratic [] qLst=new Quadratic[8];

qLst[0]=testquad1;
qLst[1]=testquad2;
qLst[2]=testquad3;
qLst[3]=testquad4;
qLst[4]=testquad5;
qLst[5]=testquad6;
qLst[6]=testquad7;
qLst[7]=testquad8;

Quadratic tmp;


// sorting Quadratic

for(int i=0;i<7;i++){
for(int j=0;j<7-i;j++){
if(qLst[j].compareTo(qLst[j+1])>0){
tmp=qLst[j];
qLst[j]=qLst[j+1];
qLst[j+1]=tmp;
}
}
}


System.out.println("\n\nSorted Quadratic ---- \n");

// print each Quadratic after sorting

for(int i=0;i<8;i++){
System.out.print("\n"+(i+1)+") : "+qLst[i]);
}

System.out.println();
}
  
}