将字符串解析为字节的NumberFormat异常？

Question

我正在尝试将以下字符串解析为Byte。但是它给了我NumberFormat Exception.body可以告诉我对此的解决方案是什么？

Byte.parseByte("11111111111111111111111110000001", 2);

Answer 1

Out of range of byte ie -128 to 127. From parseByte(String s,int radix) javadoc:

 public static byte parseByte(String s, int radix)throws NumberFormatException 

Parses the string argument as a signed byte in the radix specified by the second argument. The characters in the string must all be digits, of the specified radix (as determined by whether Character.digit(char, int) returns a nonnegative value) except that the first character may be an ASCII minus sign '-' ('\-') to indicate a negative value. The resulting byte value is returned. An exception of type NumberFormatException is thrown if any of the following situations occurs:

1. The first argument is null or is a string of length zero.
2. The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.
3. Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign '-' ('\-') provided that the string is longer than length 1.
4. The value represented by the string is not a value of type byte.

Returns: the byte value represented by the string argument in the specified radix Throws: NumberFormatException - If the string does not contain a parsable byte.

Answer 2

Byte.parseByte() handles binary string as sign-magnitude not as a 2's complement, so the longest length you can have for a byte is 7 bits with a sign.

In other words, to represent -127 , you should use:

Byte.parseByte("-111111", 2);

The following throws NumberFormatException :

Byte.parseByte("10000000", 2);

However, the binary literal of -127 is:

byte b = (byte) 0b10000000;

The same behavior is applied to the other parseXXX() methods.

Answer 3

from javadocs

An exception of type NumberFormatException is thrown if any of the following situations occurs:

• The first argument is null or is a string of length zero.
• The radix is either smaller than Character.MIN_RADIX or larger than Character.MAX_RADIX.
• Any character of the string is not a digit of the specified radix, except that the first character may be a minus sign '-' ('\-') provided that the string is longer than length 1.
• The value represented by the string is not a value of type byte.

Your value is the second case that is out of range -128 to 127

Answer 4

值太大，无法以字节为单位进行解析请尝试以下操作：

new BigInteger("011111111111111111111111110000001", 2).longValue();