A Java code for computing the roots of a quadratic equation
Below is an example of a Java code that solves a quadratic equation. The code contains instances where the equation reduces to a linear equation, has no solution, or has infinite solutions.
// JAVA CODE
import java.util.*; // Import the Scanner class and printf
import java.lang.Math; // To use sqrt() and abs() methods
class quadratic {
public static void main(String[] args) {
Scanner userIn = new Scanner(System.in); // Create a Scanner object
System.out.println("Solving quadratic equation: ax^2 + bx +c = 0");
// Ask user input the value of a, b, and c
System.out.println("Enter a: ");
double a = userIn.nextDouble();
System.out.println("Enter b: ");
double b = userIn.nextDouble();
System.out.println("Enter c: ");
double c = userIn.nextDouble();
// solving the equation
if (a == 0.0) {
if (b == 0.0) {
if (c != 0) {
System.out.println("The equation has no solutions");
} else {
System.out.println("The equation has infinite solutions");
}
} else {
double x1 = -c/b;
System.out.printf("The equation is linear and has one root, which is %.2f\n",x1);
}
} else {
double delta = b*b - 4*a*c;
if (delta == 0.0) {
double x1 = -b/(2*a);
System.out.printf("The equation has one unique real root, which is %.2f\n",x1);
} else if (delta > 0.0) {
double x1 = (-b - Math.sqrt(delta))/(2*a);
double x2 = (-b + Math.sqrt(delta))/(2*a);
System.out.printf("The equation has two real roots, which is %.2f and %.2f\n",x1,x2);
} else if (delta < 0.0) {
double realx = -b/(2*a);
double imx = (Math.sqrt(Math.abs(delta))) / (2*a);
System.out.println("The equation has two conjugate complex roots");
System.out.printf("x1 = %.2f - i(%.2f)\n", realx, Math.abs(imx));
System.out.printf("x2 = %.2f + i(%.2f)\n", realx, Math.abs(imx) );
}
}
}
}