java 在Java中将字符串转换为浮点数而不将其舍入
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Converting string to float in Java without round it
提问by Kliver Max
Possible Duplicate:
Rounding in java Float.parseFloat
I want to convert strings to float i say:
我想将字符串转换为浮点数我说：
System.out.println(Float.parseFloat("1553781.9829"));
Output:
输出：
1553782.0
I say:
我说：
System.out.println(Float.valueOf("1553781.9829"));
Output:
输出：
1553782.0
How to get Float without lossing precision?
如何在不损失精度的情况下获得浮点数？
采纳答案by vishal_aim
use System.out.println(Double.parseDouble("1553781.9829"));instead
使用System.out.println(Double.parseDouble("1553781.9829"));替代
float has a limitation of smaller size (4 bytes) so it's not good for big decimals, double has the double size (8 bytes)
float 具有较小尺寸（4 字节）的限制，因此它不适用于大小数，double 具有双倍尺寸（8 字节）
回答by rai.skumar
If you are looking for accuracy, I would suggest BigDecimal
如果您正在寻找准确性，我会建议BigDecimal
This is just like normal wrapper class which provides methods for all your operations. And yes it takes argument as String as well.
这就像普通的包装类一样，它为您的所有操作提供方法。是的，它也将参数作为字符串。
BigDecimal bd = new BigDecimal("1553781.9829");
System.out.println(" bd :"+ bd); //prints the same value
URL : http://docs.oracle.com/javase/1.5.0/docs/api/java/math/BigDecimal.html
网址：http: //docs.oracle.com/javase/1.5.0/docs/api/java/math/BigDecimal.html
回答by Evgeniy Dorofeev
You cannot use float or double without a risk of losing precision. First of all their precision is limited, for float it is approx 7-8 decimal digits, for double ~16 digits. Apart from that Java floating points types are binary internally so they cannot store some decimal fractions without losing precision. If you really need exact decimal fractions use java.math.BigDecimal. Read "Effective Java" Item 48: "Avoid float and double if exact answers are required".
您不能使用 float 或 double 而不会有失去精度的风险。首先，它们的精度是有限的，对于浮点数，它大约是 7-8 位十进制数字，对于双~16 位数字。除此之外，Java 浮点类型在内部是二进制的，因此它们无法在不损失精度的情况下存储一些小数。如果您确实需要精确的十进制分数，请使用 java.math.BigDecimal。阅读“Effective Java”第 48 条：“如果需要确切答案，请避免浮动和双倍”。
回答by Naveenkumar K
Instead of Floatyou can use Double
而不是Float你可以使用Double
System.out.println(Double.valueOf("1553781.9829"));
System.out.println(Double.parseDouble("1553781.9829"));
