CODEWITHSUNDEEP
java
Jekin Kalariya
Jekin Kalariya

Reputation: 3507

Why does Float.toString() change the numeric value?

I have a question regarding below code, where if we use the Float.toString() method it will do some rounding of digits. Why does it do this? Is there any specific logic behind that?

I have also looked at the internal code of Float.toString(). It's calling FloatingDecimal(f).toJavaFormatString().

public static void main(String[] args) {                            
    Float f = Float.intBitsToFloat(1342177280);

    String simpleString = new BigDecimal(f).toPlainString();
    System.out.println("simpleString value  " + simpleString);

    String withToString = new BigDecimal(Float.toString(f)).toPlainString();
    System.out.println("withToString value  " + withToString);
}

Output is like this

simpleString value  8589934592
withToString value  8589934600  //here value changed

Upvotes: 2

Views: 123

Answers (1)

AxelH
AxelH

Reputation: 14572

The BigDecimal constructor is simple. Give me a String, I will create a number with it. If you give me a number, I will use his value directly.

Since the String generate in your example looks like 8.5899346E9, the value in plain number is 8589934600. If you send the float instance, it will (i guess) works with the bits to recreate the value as precisly as possible.

Upvotes: 1

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