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BigDecimal Utils

Comparing BigDecimal is always hard to read and too error prone. I wrote this library to make comparison of BigDecimal more comfortable and more readable.

Maven:

    <dependency>
  	<groupId>ir.cafebabe.math.utils</groupId>
  	<artifactId>bigdecimal-utils</artifactId>
  	<version>1.3</version>
    </dependency>

Gradle:

compile 'ir.cafebabe.math.utils:bigdecimal-utils:1.3'

Gradle Kotlin DSL:

compile(group = "ir.cafebabe.math.utils", name = "bigdecimal-utils", version = "1.3")

Scala SBT:

libraryDependencies += "ir.cafebabe.math.utils" % "bigdecimal-utils" % "1.3"

Is BigDecimal Comparison happens

Sure! The only reliable way to work with monetary amount is to use BigDecimal. So if you have Money somewhere in your code, you probably found yourself comparing two BigDecimals.

What's wrong with BigDecimal comparison

Well, As you should know, if you use equal method of BigDecimal to compare two objects, they only considered equal if they are equal in value and scale thus 2.0 is not equal to 2.00 when compared by equal method (refer to JavaDocs).

To compare BigDecimal without considering their scale we should use compareTo method. This is the most common and correct way to compare two BigDecimals. However it is so error prone and lacks readability. To feel what it looks like, take a look at this line of code :

return balance.compareTo(amount) < 0) && amount.compareTo(anotherAmount) >= 0));

The above code tris to check the condition in wich "balance < amount && amount >= anotherAmount". You definitely spotted the issue here. The compareTo is not clear nor readable. But how to solve this?

How I Solve the Problem

BigDecimalUtils is a simple library that enable us to campare BigDecimal objects in more readable and less error prone way. see the same comparison rewritten by this library

import static ir.cafebabe.math.utils.BigDecimalUtils.*;

// ...

return is(balance).lt(amount) && is(amount).gte(minAmount));

Other methods in this library:

  is(bigdecimal).eq(four); // equal
  is(bigdecimal).gt(two); // greater than
  is(bigdecimal).gte(one); // greater than equal
  is(bigdecimal).lt(two); // less than
  is(bigdecimal).lte(two); // less than equal

  is(bigdecimal).notEq(four); // not equal
  is(bigdecimal).notGt(two); // not greater than
  is(bigdecimal).notGte(one); // not greater than equal
  is(bigdecimal).notLt(two); // not less than
  is(bigdecimal).notLte(two); // not less than equal

  is(bigdecimal).isZero(); 	
  is(bigdecimal).notZero(); 
  is(bigdecimal).isPositive(); // greater than zero
  is(bigdecimal).isNegative(); // less than zero
  is(bigdecimal).isNonPositive(); // less than or equal zero
  is(bigdecimal).isNonNegative(); // greater than or equal zero

  is(bigdecimal).isNullOrZero(); // is null or zero
  is(bigdecimal).notNullOrZero(); // not null or zero

You can also compare a BigDecimal to other numerical values. For instance instead of writing

  is(bigdecimal).notEq(BigDecimal.valueOf(4));

you can simply and interchangeably write:

  is(bigdecimal).notEq(4);
  is(bigdecimal).notEq(4L);
  is(bigdecimal).notEq(4D);

Why BigDecimal Utils?

I didn't find any library to handle BigDecimal comparison. If you found one please let me know.