CODEWITHSUNDEEP
java
bsiamionau
bsiamionau

Reputation: 8229

Why are Integer.parseInt(String s, 2) and Integer.toBinaryString(int i) incompatible?

Why are this two methods using two different approaches while processing binary numbers? String which represents negative binary number in Integer.parseInt(String s, 2) method should start with - character, but Integer.toBinaryString(int i) returns string with additional 1 ahead. So, this code

Integer.parseInt(Integer.toBinaryString(-1), 2);

throws java.lang.NumberFormatException. What is the reason of such behavior?

Upvotes: 2

Views: 1732

Answers (2)

R Kaja Mohideen
R Kaja Mohideen

Reputation: 917

Integer::parseInt(String,int) is expecting a string and so it is looking for the - symbol in negative number. Whereas the Integer::toBinaryString(int) is for giving you the binary equivalent of your input. In Binary, negative numbers are represented by 2's Compliment.

Upvotes: 0

Fred Foo
Fred Foo

Reputation: 363817

This is by design; Integer.toBinaryString

Returns a string representation of the integer argument as an unsigned integer in base 2.

(emphasis added).

I.e., toBinaryString provides a way to format an integer as the common two's complement representation, which is the way most processors actually store signed integers internally.

Upvotes: 2

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