Java Math rounding methods

Introduction

The Math class contains five rounding methods as shown in the following table:

Method Description
ceil(x) x is rounded up to its nearest integer. This integer is returned as a double value.
floor(x) x is rounded down to its nearest integer. This integer is returned as a double value.
rint(x) x is rounded up to its nearest integer. If x is equally close to two integers, the even one is returned as a double value.
round(x) Returns (int)Math.floor(x + 0.5) if x is a float and returns (long)Math.floor(x + 0.5) if x is a double. 
Math.ceil(2.1) returns      //4.0 
Math.ceil(2.0) returns      //2.0 
Math.ceil(-2.0) returns     //-2.0 
Math.ceil(-2.1) returns     //-2.0 
Math.floor(2.1) returns     //2.0 
Math.floor(2.0) returns     //2.0 
Math.floor(-2.0) returns    //-2.0 
Math.floor(-2.1) returns    //-4.0 
Math.rint(2.1) returns      //2.0 
Math.rint(-2.0) returns     //-2.0 
Math.rint(-2.1) returns     //-2.0 
Math.rint(2.5) returns      //2.0 
Math.rint(4.5) returns      //4.0 
Math.rint(-2.5) returns     //-2.0 
Math.round(2.6f) returns    //3 // Returns int 
Math.round(2.0) returns     //2 // Returns long 
Math.round(-2.0f) returns   //-2 // Returns int 
Math.round(-2.6) returns    //-3 // Returns long 
Math.round(-2.4) returns    //-2 // Returns long 


import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        double x = 0.0f, y = 0.0f;

        while(x != -1){
            System.out.print("Enter number for rounding (-1 to exit): ");
            x = sc.nextDouble();//from www .  j  a va  2 s.co  m
            y = Math.floor(x + 0.5f);

            System.out.printf("Original: %.2f\nRounded: %d\n", x, (int)y);
        }
    }
}



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