Thread: Square root not working

This is my program that does the distance formula for you. I don't understand why it can't find the method for doing square root unless that changed? My code is here and the error is below it.

import java.lang.Math;
 
public class Distance_Formula {
 
	public static void main(String [] args) {
 
		userInput input = new userInput();
		double x1 = 0.0;
		double x2 = 0.0;
		double y1 = 0.0;
		double y2 = 0.0;
		double distancePreSquareRoot = 0.0;
		double distancePostSquareRoot = 0.0;
		String x1prompt = "Enter the X1 value: ";
		String x2prompt = "Enter the X2 value: ";
		String y1prompt = "Enter the Y1 value: ";
		String y2prompt = "Enter the Y2 value: ";
 
		input.getUserInput(x1prompt);
		x1 = Double.parseDouble(input.input);
		input.getUserInput(x2prompt);
		x2 = Double.parseDouble(input.input);
		input.getUserInput(y1prompt);
		y1 = Double.parseDouble(input.input);
		input.getUserInput(y2prompt);
		y2 = Double.parseDouble(input.input);
 
		distancePreSquareRoot = (((x2 - x1) * (x2 - x1)) + ((y2 - y1) * (y2 - y1)));
 
		distancePostSquareRoot = sqrt(distancePreSquareRoot);
 
		System.out.println("The distance between (" + x1 + "," + y1 + " and (" + x2 + "," + y2 + ") is: " + distancePostSquareRoot);
 
 
	}
 
}

Error:

Distance_Formula.java:30: cannot find symbol
symbol  : method sqrt(double)
location: class Distance_Formula
                distancePostSquareRoot = sqrt(distancePreSquareRoot);
                                         ^
1 error
Press any key to continue . . .

In Java there's no such thing as a "global" variable/method. Thus, for methods outside of your current class (including the inheritance hierarchy) you must quantify where that variable/method came from.

distancePostSquareRoot = Math.sqrt(distancePreSquareRoot); // sqrt is found inside the Math class as a static method

An alternative available starting in SE 5 is something known as "static imports". This lets you do things such as importing static methods/variables and using them without needing to quantify where they come from. Note that you should be careful when using static imports.

import static java.lang.Math.sqrt;
 
public class SomeClass
{
    public static void main(String[] args)
    {
        double a = sqrt(5);
    }
}