how to convert integer to bigdecimal in java

Question

I want to create a method that caculates multiplication an integer and a bigdecimal. I search on google and forums nothing I found.

import java.math.BigDecim         


        

Answer 1

To multiply an integer (or byte/short/float/double) with a BigInteger (or BigDecimal), you must convert the native number to BigInteger/BigDecimal first.

// int parameter can be int or Integer
public static BigInteger multiply ( int a, BigInteger b ) {
   return BigInteger.valueOf( a ).multiply( b );
}

// BigInteger <> BigDecimal
public static BigDecimal multiply ( int a, BigDecimal b ) {
   return BigDecimal.valueOf( a ).multiply( b );
}

// same for add, subtract, divide, mod etc.

Note: valueOf is not the same as new, and for different reasons on BigDecimal and BigInteger. In both cases, I recommend valueOf over new.

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I see that you added your code, nice. It doesn't work because Integer is mixed with BigDecimal, and also * does not work with BigDecimal. If you compare it with my code, the fix should be obvious:

public BigDecimal methCal ( int quantite, BigDecimal prixUnit ) {
    return BigDecimal.valueOf( quantite ).multiply( prixUnit );
}