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NumberUtil

NumberUtil

Origin

The digital tool is a tool-based encapsulation for mathematical operations.

Usage

Basic Arithmetic Operations

  • NumberUtil.add for addition of numeric types
  • NumberUtil.sub for subtraction of numeric types
  • NumberUtil.mul for multiplication of numeric types
  • NumberUtil.div for division of numeric types, with overloaded methods to specify the number of decimal places to retain and the rounding mode in case of inexact division.

All four operations convert double to BigDecimal before calculation, solving the problem of inaccurate calculations with float and double types. These methods are often used in commercial calculations.

Retaining Decimal Places

There are two main methods for retaining decimal places:

  • NumberUtil.round mainly encapsulates the methods in BigDecimal to retain decimal places, returning a BigDecimal. This method is more flexible and can choose rounding modes such as rounding up or down.
double te1=123456.123456;
double te2=123456.128456;
Console.log(round(te1,4));//result:123456.1235
Console.log(round(te2,4));//result:123456.1285
  • NumberUtil.roundStr mainly encapsulates the String.format method, and the rounding mode adopts rounding up.
double te1=123456.123456;
double te2=123456.128456;
Console.log(roundStr(te1,2));//result:123456.12
Console.log(roundStr(te2,2));//result:123456.13

DecimalFormat

A simple encapsulation of DecimalFormat.format, which formats double or long numbers according to a fixed format.

long c=299792458;//speed of light
String format = NumberUtil.decimalFormat(",###", c);//299,792,458

The format mainly uses the placeholder symbols # and 0 to specify the number length. 0 indicates that the digit is filled with 0 if the position is insufficient, # indicates that the digit is pulled to this position if possible.

  • 0 -> take one integer digit
  • 0.00 -> take one integer digit and two decimal places
  • 00.000 -> take two integer digits and three decimal places
  • # -> take all integer parts
  • #.##% -> count as a percentage with two decimal places
  • #.#####E0 -> display as scientific notation with five decimal places
  • ,### -> separate every three digits with a comma, e.g., 299,792,458
  • The speed of light is ,### meters per second -> embed the format in the text

For more information about the format, please refer to: Java DecimalFormat的主要功能及使用方法 (Main Functions and Usage of Java DecimalFormat)

Whether a Number

  • NumberUtil.isNumber to check if it is a number
  • NumberUtil.isInteger to check if it is an integer
  • NumberUtil.isDouble to check if it is a floating point number
  • NumberUtil.isPrimes to check if it is a prime number

Random Numbers

  • NumberUtil.generateRandomNumber to generate non-repeating random numbers based on the given minimum and maximum numbers and the number of random numbers to generate a specified non-repeating array.
  • NumberUtil.generateBySet to generate non-repeating random numbers based on the given minimum and maximum numbers and the number of random numbers to generate a specified non-repeating array.

Integer List

The NumberUtil.range method generates an ordered integer list based on the range and step size. NumberUtil.appendRange adds integers within the given range to an existing set.

Others

  • NumberUtil.factorial for factorial calculations
  • NumberUtil.sqrt for square root calculations
  • NumberUtil.divisor for calculating the greatest common divisor (GCD)
  • NumberUtil.multiple for calculating the least common multiple (LCM)
  • NumberUtil.getBinaryStr for obtaining the binary string corresponding to a number
  • NumberUtil.binaryToInt binary to int
  • NumberUtil.binaryToLong binary to long
  • NumberUtil.compare compare two values
  • NumberUtil.toStr convert number to string, automatically remove trailing zeros after decimal point
RuntimeUtilArrayUtil