题
我想对一些以以下形式表示的货币值进行一些简单的求和 BigDecimal
类型。
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);
显然我不太理解 BigDecimal
算术,见后面的输出。
Test
0
0
0
谁能帮我吗?
解决方案
在BigDecimal
是不可改变的,所以你需要做的:
BigDecimal result = test.add(new BigDecimal(30));
System.out.println(result);
其他提示
它看起来像从Java文档这里其添加返回一个新的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);
这实际上相当容易。只需这样做:
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);
的BigInteger是不可变的,你需要做的,
BigInteger sum = test.add(new BigInteger(30));
System.out.println(sum);
//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
您也可以做到这一点是这样的:
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);
打印:
A + B + C = 600亿
BigDecimal demo = new BigDecimal(15);
它是不可变的怎么一回事,因为它在内部存储你输入即(15),作为final private final BigInteger intVal;
在字符串创建时相同的概念使用每个输入最后存储
private final char value[];
.So没有implmented错误。
又一个例子来添加BigDecimals
。关键的一点是,他们是不可改变的,它们只能在构造函数初始化。下面是代码:
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());
}
}
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