How to convert a value of type BigDecimal to a double type

Preface

In Java,BigDecimalCan be converted todoubleType, but it should be noted that such conversion may result in accuracy loss becauseBigDecimalThe accuracy ratiodoubleMuch taller.

Here isBigDecimalConvert todoubleMethod:

Use the doubleValue method

BigDecimalProvideddoubleValueMethod to convert todoubletype.

import ;

public class Main {
    public static void main(String[] args) {
        BigDecimal bigDecimal = new BigDecimal("12345.6789");

        // Convert BigDecimal to double        double doubleValue = ();

        ("BigDecimal value: " + bigDecimal);
        ("Double value: " + doubleValue);
    }
}

In this example,()Will beBigDecimalConvert todoubleand store the result indoubleValuein variable.

Things to note

• Precision loss:becausedoubleThe accuracy limitations of   may cause numerical distortion in some cases. Therefore, be extra careful when conducting financial calculations and other scenarios that require high accuracy.
• Range Limitation：BigDecimalRange ratiodoubleMuch bigger. ifBigDecimalThe value exceedsdoubleThe range of   will cause the result toInfinityor-Infinity。

Example

Here is a complete example showing how toBigDecimalConvert todoubleAnd pay attention to accuracy issues:

import ;

public class Main {
    public static void main(String[] args) {
        BigDecimal bigDecimal1 = new BigDecimal("12345.6789");
        BigDecimal bigDecimal2 = new BigDecimal("1.2345678901234567890123456789E+20");

        // Convert BigDecimal to double        double doubleValue1 = ();
        double doubleValue2 = ();

        ("BigDecimal value 1: " + bigDecimal1);
        ("Double value 1: " + doubleValue1);
        ("BigDecimal value 2: " + bigDecimal2);
        ("Double value 2: " + doubleValue2);
    }
}

Output example:

BigDecimal value 1: 12345.6789
Double value 1: 12345.6789
BigDecimal value 2: 1.2345678901234567890123456789E+20
Double value 2: 1.2345678901234568E20

You can see that for larger values,doubleThe conversion will lose some accuracy. This is especially important when performing high-precision calculations.

Attachment: Note that double cannot force conversion to BigDecimal

public class Test {
	public static void main(String args[]) {
		double b_OLD = 4.1625;
		<a target="_blank" href="/search?word=&fr=qb_search_exp&ie=utf8" rel="nofollow"></a>.BigDecimal bd1 = new <a target="_blank" href="/search?word=&fr=qb_search_exp&ie=utf8" rel="nofollow"></a>.BigDecimal( b_OLD );
		("BEFORE ROUNDING: " + bd1);
	}
}

The BigDecimal class can be initialized with the double type.

Follow up

Then why
        double  b = 4.44;
               big = ( )b;
Can't convert this way? Is there any difference?

answer

Because double is a basic data type, it cannot be cast. Casting is for Object. Double b = 4.44; This is not possible, because BigDecimal does not inherit from Double, so there is no way to cast type conversion.

Summarize

This is the article about how Java converts BigDecimal value into double type. For more related Java to convert BigDecimal value into double type, please search for my previous article or continue browsing the related articles below. I hope everyone will support me in the future!