why ch1 == ch2 is false, doesn't it hold the same char values?

Question

I'm trying to compare two char primitives ch1 and ch2. Both are assigned the value 1 as shown below.

But when compared using the "==" operator it returns false, which I don't understand how or what's happening behind the scenes.

char ch1 = (char)1;
char ch2 = '1';
System.out.println(ch1==ch2); //false

//further comparisions
System.out.println(ch1 == 1);       //true
System.out.println(ch1 == '\u0031'); //false

System.out.println(ch2 == 1);       //false
System.out.println(ch2 == '\u0031'); //true

Answer 1

'1' has the value 49 (31 hexadecimal).

(char)1 has the value 1.

A char is just a 16-bit integer. The notation 'x' means 'the character code for the character x', where the encoding used in Java is Unicode, specifically UTF-16.

The cast (char) does not change the value of the expression to its right, except that it truncates it from a full-size integer to 16 bits (which is no change for values 0 to 65535).

Answer 2

Basically what you are doing is casting the number one as a char, so ch1 is now equals to unicode character 1 (SOH or Start of Header)

So when you compare ch1 (SOH) to ch2 ('1') its going to return false As well if you compare ch1 (SOH - ) to `'1' - 1 is going to return false

That's the main reason why is returning false, the unicode value of ch1 that you expect is different from the one you assigned

Answer 3

Code point

The char type is essentially broken since Java 2, physically incapable of representing most characters.

Instead use code point integer numbers. Every character is permanently assigned a specific number, a code point.

int codePoint = "1".codePointAt( 0 ) ;  // Annoying zero-based index counting. 

The result is 49 decimal, 31 hexadecimal.

Make a string of that single character per the code point.

String s = Character.toString( codePoint ) ;

Or more specifically:

String latinDigitOneCharacter = Character.toString( 49 ) ;

As others pointed out, your code was mistakenly comparing the character defined as the Latin digit “1” with a code point of 1.

The character assigned to the code point of one is the control code SOH, Start of Heading. This is true in both Unicode and US-ASCII (Unicode is a superset of US-ASCII).