JAVA中使用BigDecimal解决货币问题
BigDecimal使用的时候 切记传递进去的参数是String 类型 否则得不到我们想要的记过
具体原因
我们通过鼠标+Ctril
可以查看其方法的定义
* The results of this constructor can be somewhat unpredictable.
* One might assume that writing {@code new BigDecimal(0.1)} in
* Java creates a {@code BigDecimal} which is exactly equal to
* 0.1 (an unscaled value of 1, with a scale of 1), but it is
* actually equal to
* 0.1000000000000000055511151231257827021181583404541015625.
* This is because 0.1 cannot be represented exactly as a
* {@code double} (or, for that matter, as a binary fraction of
* any finite length). Thus, the value that is being passed
* <i>in</i> to the constructor is not exactly equal to 0.1,
* appearances notwithstanding.
*
<li>
* When a {@code double} must be used as a source for a
* {@code BigDecimal}, note that this constructor provides an
* exact conversion; it does not give the same result as
* converting the {@code double} to a {@code String} using the
* {@link Double#toString(double)} method and then using the
* {@link #BigDecimal(String)} constructor. To get that result,
* use the {@code static} {@link #valueOf(double)} method.
* </ol>
converting the {@code double} to a {@code String} using the
下面附上具体的测试代码
import org.junit.Test;
import java.math.BigDecimal;
/**
* Created by YDLin
*/
public class BigDecimalTest {
@Test
public void test1(){
System.out.println(0.05+0.01);
System.out.println(1.0-0.42);
System.out.println(4.015*100);
System.out.println(123.3/100);
}
@Test
public void test2(){
BigDecimal b1 = new BigDecimal(0.05);
BigDecimal b2 = new BigDecimal(0.01);
System.out.println(b1.add(b2));
}
@Test
public void test3(){
BigDecimal b1 = new BigDecimal("0.05");
BigDecimal b2 = new BigDecimal("0.01");
System.out.println(b1.add(b2));
}
}