How to convert BigDecimal to/from String in java examples

In this blog post, We are going to learn about BigInteger examples on

Create BigInteger object using constructor, Example new BigInteger(123)
How to Convert String from BigDecimal
How to convert BigDecimal to String

java.math.BigDecimal class in java

This is a data type that can be used in financial and ERP applications where the precision of a number is important. BigDecimal is used to store the rounding of the numbers after arithmetic operations. It is an immutable type.

BigDecimal is a class declared in the java.math package of java language.

How do you create a BigDecimal in java?

Objects can be created using the constructor with string or double parameters.

an example:

// constructor with String parameter
BigDecimal bigDecimal = new BigDecimal("147.87932");
System.out.println(bigDecimal);

// constructor with Double parameter
BigDecimal bigDecimal1 = new BigDecimal(147.87932);
System.out.println(bigDecimal1);

Output:

147.87932
147.8793200000000069849193096160888671875

First example, create an object using the constructor with a string value, returned the correct actual value.

The second, created using the constructor with a double value, 147.87932 is converted to the closest double value 147.8793200000000069849193096160888671875.

Hope you understand How the BigDecimal object is created in java.

How to convert BigDecimal to String with an example in java?

In Java, we can convert BigDecimal to String in multiple ways.
The first is with the toString method, and the second is the toEngineeringString method. Finally, simple toPlainString method

Using toString() method

toString() method is available in any java class that extends java.lang.object class. It returns number string’s as String output. Syntax:

BigDecimal.toString()

code:

MathContext m = new MathContext(3);
BigDecimal bg = new BigDecimal("3617E+4", m);
System.out.println(bg.toString());
BigDecimal bd3 = new BigDecimal("567.12345678901234561243");
System.out.println(bd3.toString());

output:

3.62E+7
567.12345678901234561243

Using toEngineeringString() method

This is also simple to convert with this approach.

The function toEngineeringString() returns the String value of a Bigdecimal object that does not have a exponent field. However, when compared to the function toString() method, this approach does not return the correct value in terms of scale value.

Syntax:

public String toEngineeringString()

Here is a complete example

MathContext m = new MathContext(3);
BigDecimal bg = new BigDecimal("3617E+4", m);
System.out.println(bg.toEngineeringString());
BigDecimal bd3 = new BigDecimal("567.12345678901234561243");
System.out.println(bd3.toEngineeringString());

output:

36.2E+6
567.12345678901234561243

Using toPlainString() method

Third, there’s toPlainString(), which returns a plain String of a bigdecimal object without the exponent field.

Syntax:

public String toPlainString()

MathContext m = new MathContext(3);
BigDecimal bg = new BigDecimal("3617E+4", m);
System.out.println(bg.toPlainString());
BigDecimal bd3 = new BigDecimal("567.12345678901234561243");
System.out.println(bd3.toPlainString());

output:

36200000
567.12345678901234561243

String valueOf() method

It is an easy method and The String.valueOf() function in Java returns a string representation of any class.

Syntax:

String.valueOf(AnyObject)

Input parameter:

Any object in class, like BigDecimal Returns:
string version of a provided object, in this case, BigDecimal Object

Example:

MathContext mc = new MathContext(3);
BigDecimal bd = new BigDecimal("1237E+4", mc);
System.out.println(String.valueOf(bd));
BigDecimal bd1 = new BigDecimal("123.12345678901234561243");
System.out.println(String.valueOf(bd1));

Output:

1.24E+7
123.12345678901234561243

How to Convert String to BigDecimal in Java?

It is very easy to do the conversion to BigDecimal from a given string, The simple approach is using the BigDecimal constructor

Syntax:

BigDecimal(String)

This constructor accepts string value, where the string is a number enclosed in double-quotes.

If the given number is not a number enclosed as a string, it gives NumberFormatException runtime error.

String stringObject="123.45";
BigDecimal bigDecimalObject=new BigDecimal(stringObject);
System.out.println(bigDecimalObject);

Output:

123.45

NumberFormatException error This issue comes when the string contains a non-numeric character

String stringObject="123.45";
BigDecimal bigDecimalObject=new BigDecimal(stringObject);
System.out.println(bigDecimalObject);

and output is

Exception in thread "main" java.lang.NumberFormatException

Conclusion

The fix is to BigDecimal will convert the string which contains numbers only. Try to avoid the String with non-numeric characters only.

Hope you understand the conversion of string and BigInteger in java.