Hey folks, this post is about a Math Package:NumberUtils.It has few handful of utility methods. All methods are static, so you don’t have to create an instance of it. It resides in org.apache.commons.lang3.math.NumberUtils package. You can download the jar from http://commons.apache.org/proper/commons-lang/.
Or using Maven
<groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.3.2</version>
and an import is necessary import org.apache.commons.lang3.math.NumberUtils;
Here is an example on how to go about using this Library.
1. Example
NU.java
package com.javacodegeek;
import java.math.BigDecimal;
import org.apache.commons.lang3.Conversion;
import org.apache.commons.lang3.math.NumberUtils;
public class NU {
public static void main(String[] args) {
// TODO Auto-generated method stub
ConvertBigDecimal("111");
checkWhetherNumberLegacy("111");
checkWhetherNumberRegex("111");
checkWhetherNumberRegex("10E-3");
NUStyle("111");
NUStyle("10E-3");
NUIntMax(new int[]{1,2,5,3,77,5});
NUIntMin(new int[]{1,2,5,3,77,5});
float minusone = NumberUtils.FLOAT_MINUS_ONE;
}
public static void ConvertBigDecimal(String input) throws NumberFormatException{
BigDecimal bd = NumberUtils.createBigDecimal(input);
System.out.println("ConvertBigDecimal:"+input+" "+bd);
}
public static void checkWhetherNumberLegacy(String input){
try {
Integer.parseInt(input);
System.out.println("checkWhetherNumberLegacy:"+input+" true");
}
catch (NumberFormatException e) {
System.out.println("checkWhetherNumberLegacy:"+input+" false");
}
}
public static void checkWhetherNumberRegex(String input){
System.out.println("checkWhetherNumberRegex:"+input
+" "+input.matches("[-+]?\\d+(\\.\\d+)?"));
}
public static void NUStyle(String input){
boolean res1 = NumberUtils.isNumber(input);
System.out.println("NUStyle:"+input+" "+res1);
}
public static void NUIntMax(int[] arr){
int max = NumberUtils.max(arr);
System.out.println("NUIntMax: "+max);
}
public static void NUIntMin(int[] arr){
int min = NumberUtils.min(arr);
System.out.println("NUIntMax: "+min);
}
}
Output
ConvertBigDecimal:111 111 checkWhetherNumberLegacy:111 true checkWhetherNumberRegex:111 true checkWhetherNumberRegex:10E-3 false NUStyle:111 true NUStyle:10E-3 true NUIntMax: 77 NUIntMax: 1
2. Conversion
Following method will convert a String to a BigDecimal format
public static void ConvertBigDecimal(String input) throws NumberFormatException{
BigDecimal bd = NumberUtils.createBigDecimal(input);
System.out.println("ConvertBigDecimal:"+input+" "+bd);
}
2.1. Other Conversion methods
createBigDecimal(String str)will return a BigDecimalcreateBigInteger(String str)will return an BigIntegercreateDouble(String str)will return a DoublecreateFloat(String str)will return a FloatcreateInteger(String str)will return a Integer on providing hex and octal notions alsocreateLong(String str)will return a LongcreateNumber(String str)will return a NumbertoByte(String str)will return a Byte, return 0 if conversion failstoByte(String str, byte defaultValue)will return Byte, if conversion fails will return default value.toDouble(String str)will return a Double, return 0 if conversion failstoDouble(String str, double defaultValue)will return a Double, if conversion fails will return default value.toFloat(String str)will return a float, return 0 if conversion failstoFloat(String str, float defaultValue)will return a float, if conversion fails will return default valuetoInt(String str)will return Int, return 0 if conversion failstoInt(String str, int defaultValue)will return an InttoLong(String str)will return a Long, return 0 if conversion failstoLong(String str, long defaultValue)will return a Long, if conversion fails will return default value.toShort(String str)returns a Short, return 0 if conversion failstoShort(String str, short defaultValue)returns Short, default value on failed attempt to convert.
3. Finding maximum values
public static void NUIntMax(int[] arr){
int max = NumberUtils.max(arr);
System.out.println("NUIntMax: "+max);
}
The following methods provide a convenient way to find out maximum values in a given array.
max(byte[] array)max(byte a, byte b, byte c)max(double[] array)max(double a, double b, double c)max(float[] array)max(float a, float b, float c)max(int[] array)max(int a, int b, int c)max(long[] array)max(long a, long b, long c)max(short[] array)max(short a, short b, short c)
4. Finding minimum values
public static void NUIntMin(int[] arr){
int min = NumberUtils.min(arr);
System.out.println("NUIntMax: "+min);
}
The following methods provide a convenient way to find out minimum values in a given array.
min(byte[] array)min(byte a, byte b, byte c)min(double[] array)min(double a, double b, double c)min(float[] array)min(float a, float b, float c)min(int[] array)min(int a, int b, int c)min(long[] array)min(long a, long b, long c)min(short[] array)min(short a, short b, short c)
5. Ways to find whether a string is a Number
public static void checkWhetherNumberLegacy(String input){
try {
Integer.parseInt(input);
System.out.println("checkWhetherNumberLegacy:"+input+" true");
}
catch (NumberFormatException e) {
System.out.println("checkWhetherNumberLegacy:"+input+" false");
}
}
Or you can do something like…
public static void checkWhetherNumberRegex(String input){
System.out.println("checkWhetherNumberRegex:"
+input+" "+input.matches("[-+]?\\d+(\\.\\d+)?"));
}
}
but what about formats like “10E-3” which is a valid number format. regex will fail in that case. The solution would be more POWERFUL regex… EH… no not really. NumberUtils does have a neat solution.
public static void NUStyle(String input){
boolean res1 = NumberUtils.isNumber(input);
System.out.println("NUStyle:"+input+" "+res1);
boolean res2 = NumberUtils.isDigits(input);
System.out.println("NUStyle:"+input+" "+res2);
}
Returns true or false. Not having to worry about handling exceptions.
6. Some Resusable static Constants to save memory
public static void NUStyle(String input){
float minusonef = NumberUtils.FLOAT_MINUS_ONE;
}
BYTE_MINUS_ONEBYTE_ONEBYTE_ZERODOUBLE_MINUS_ONEDOUBLE_ONEDOUBLE_ZEROFLOAT_MINUS_ONEFLOAT_ONEFLOAT_ZEROINTEGER_MINUS_ONEINTEGER_ONEINTEGER_ZEROLONG_MINUS_ONELONG_ONELONG_ZEROSHORT_MINUS_ONESHORT_ONESHORT_ZERO
Conclusion
NumberUtils is no rocket science package but has some daily utility static methods and static constants which can make your life a little bit easier, but only a little bit :).
Download
You can download the source code of this example here: NumberUtilsExample.zip
You can download the source code of this example here: NumberUtilsExample.zip
