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javanumberslanguage-designstandard-libraryjava-7

Why do the valueOf/parse methods on the number classes reject valid numbers in Java 7?

Neither underscores:

scala> java.lang.Float.valueOf("1_2_3.4_5_6")
java.lang.NumberFormatException: For input string: "1_2_3.4_5_6"
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1242)
    at java.lang.Float.valueOf(Float.java:416)

nor binary literals work:

scala> java.lang.Byte.valueOf("0b01010101")
java.lang.NumberFormatException: For input string: "0b01010101"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:492)
    at java.lang.Byte.parseByte(Byte.java:148)
    at java.lang.Byte.valueOf(Byte.java:204)
    at java.lang.Byte.valueOf(Byte.java:230)

What's the reason those methods weren't updated for the changes in the Java language?

(I'm working with OpenJDK 64-Bit Server VM, Java 1.7.0_136-icedtea actually.)

Solution

  • I looked at Double. I expect other Numbers are similar:

    The syntax specified by the valueOf method in Java 7 did not change from the valueOf method in Java 6. Java 7's API specifically states that underscores aren't allowed.

    Underscores will be allowed in numeric literals, not parsable strings. This was most likely @Voo's meaning by java identifiers.