Math class is part of java.lang package and provides basic mathematical operations as shown in the example below:

Java Code:
double aNumber = -123.234;

System.out.println("The absolute value of " + aNumber + " is " + Math.abs(aNumber));
System.out.println("The ceiling of " + aNumber + " is " + Math.ceil(aNumber));
System.out.println("The floor of " + aNumber + " is " + Math.floor(aNumber));
Output:

Java Code:
The absolute value of -123.234 is 123.234
The ceiling of -123.234 is -123.0
The floor of -123.234 is -124.0