On this document we will be showing a java example on how to use the acos(value a) method of Math Class. The acos(value a) returns the arc cosine of the method argument value. The following rule must be noted

  • If the argument is NaN or its absolute value is greater than 1, then the result is NaN.

The arc cosine of value is basically just the inverse cosine of a value. To further illustrate this below is the equation.

acos(a) = cos-1a

Most of the methods of the Math class is static and the acos() method is no exception. Thus don’t forget that in order to call this method, you don’t have to create a new object. Use the method in the format Math.acos(a).

Method Syntax

public static double acos(double a)

Method Returns

The acos() method returns the arc cosine of the argument.


Requires Java 1.0 and up

Java Math acos() Example

Below is a java code demonstrates the use of acos() method of Math class. The example presented might be simple however it shows the behavior of the acos() method.


import java.util.Scanner;

 * This example source code demonstrates the use of  
 * acos() method of Math class

public class MathAcosExample {

	public static void main(String[] args) {
		// Ask for user input
		System.out.print("Enter a value:");
		// use scanner to read the console input
		Scanner scan = new Scanner(;
		// Assign the user to String variable
		String s = scan.nextLine();
		// close the scanner object
		// get the arc cosine value of the user input
		double acosValue = Math.acos(Double.parseDouble(s));		
		System.out.println("arc cosine of " + s + " is " + acosValue);



The above java example source code demonstrates the use of acos() method of Math class. We simply ask for user input and we use the Scanner class to parse it. Since we have used the nextLine() method to get the console value, and the return data type is String thus we have used the Double.parseDouble() to transform it into double. We have to convert it first to double because the acos() method accepts double method argument.

Sample Output

Below is the sample output when you run the above example.

java lang Math acos() example output