Addition for BigDecimal

I want to do some simple sums with some currency values expressed in BigDe开发者_开发问答cimal type.

BigDecimal test = new BigDecimal(0);
System.out.println(test);
test.add(new BigDecimal(30));
System.out.println(test);
test.add(new BigDecimal(45));
System.out.println(test);

Obviously I do not understand well the BigDecimal arithmetics, see output behind.

Test
0
0
0

Can anyone help me out?

---

The BigDecimal is immutable so you need to do this:

BigDecimal result = test.add(new BigDecimal(30));
System.out.println(result);

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It looks like from the Java docs here that add returns a new BigDecimal:

BigDecimal test = new BigDecimal(0);
System.out.println(test);
test = test.add(new BigDecimal(30));
System.out.println(test);
test = test.add(new BigDecimal(45));
System.out.println(test);

---

BigDecimal test = new BigDecimal(0);
System.out.println(test);
test = test.add(new BigDecimal(30));
System.out.println(test);
test = test.add(new BigDecimal(45));
System.out.println(test);

---

BigInteger is immutable, you need to do this,

  BigInteger sum = test.add(new BigInteger(30));  
  System.out.println(sum);

---

It's actually rather easy. Just do this:

BigDecimal test = new BigDecimal(0);
System.out.println(test);
test = test.add(new BigDecimal(30));
System.out.println(test);
test = test.add(new BigDecimal(45));
System.out.println(test);

See also: BigDecimal#add(java.math.BigDecimal)

---

//you can do in this way...as BigDecimal is immutable so cant set values except in constructor

BigDecimal test = BigDecimal.ZERO;
BigDecimal result = test.add(new BigDecimal(30));
System.out.println(result);

result would be 30

---

BigDecimal no = new BigDecimal(10); //you can add like this also
no = no.add(new BigDecimal(10));
System.out.println(no);

---

20

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You can also do it like this:

BigDecimal A = new BigDecimal("10000000000");
BigDecimal B = new BigDecimal("20000000000");
BigDecimal C = new BigDecimal("30000000000");
BigDecimal resultSum = (A).add(B).add(C);
System.out.println("A+B+C= " + resultSum);

Prints:

A+B+C= 60000000000

---

BigInteger is immutable, just like Strings. That means we cannot change it's content once the object is created, but we can re-assign it.

 BigInteger sum = test.add(new BigInteger(30));  
 System.out.println(sum);

.add() will return a new Object

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Using Java8 lambdas

List<BigDecimal> items = Arrays.asList(a, b, c, .....);

items.stream().filter(Objects::nonNull).reduce(BigDecimal.ZERO, BigDecimal::add);

This covers cases where the some or all of the objects in the list is null.

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BigDecimal demo = new BigDecimal(15);

It is immutable beacuse it internally store you input i.e (15) as final private final BigInteger intVal; and same concept use at the time of string creation every input finally store in private final char value[];.So there is no implmented bug.

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Just another example to add BigDecimals. Key point is that they are immutable and they can be initialized only in the constructor. Here is the code:

import java.util.*;
import java.math.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc;
        boolean first_right_number = false;
        BigDecimal initBigDecimal = BigDecimal.ZERO;
        BigDecimal add1 = BigDecimal.ZERO;
        BigDecimal add2 = BigDecimal.ZERO;

        while (!first_right_number)
        {
            System.out.print("Enter a first single numeric value: ");
            sc = new Scanner(System.in);
            if (sc.hasNextBigDecimal()) 
            {
                first_right_number = true;
                add1 = sc.nextBigDecimal();
            }
        }

        boolean second_right_number = false;
        while (!second_right_number)
        {
            System.out.print("Enter a second single numeric value: ");
            sc = new Scanner(System.in);
            if (sc.hasNextBigDecimal()) 
            {
                second_right_number = true;
                add2 = sc.nextBigDecimal();
            }
        }
        BigDecimal result = initBigDecimal.add(add1).add(add2);
        System.out.println("Sum of the 2 numbers is: " + result.toString());
    }
}