Conversion between character and int in Java

Question

You cannot convert from int to char, so this would be illegal int i = 88; char c = i;,

However this is allowed char c = 88;.

Isn't a plain number and int literal? How is this allowed?

Answer 1

char is effectively an unsigned 16-bit integer type in Java.

Like other integer types, you can perform an assignment conversion from an integer constant to any integer type so long as it's in the appropriate range. That's why

byte b = 10;

works too.

From the JLS, section 5.2:

In addition, if the expression is a constant expression (§15.28) of type byte, short, char or int :

• A narrowing primitive conversion may be used if the type of the variable is byte, short, or char, and the value of the constant expression is representable in the type of the variable.
• A narrowing primitive conversion followed by a boxing conversion may be used if the type of the variable is :
  • Byte and the value of the constant expression is representable in the type byte.
  • Short and the value of the constant expression is representable in the type short.
  • Character and the value of the constant expression is representable in the type char.

Answer 2

Actually, converting from int to char is legal, it just requires an explicit cast because it can potentially lose data:

int i = 88; 
char c = (char) i;

However, with the literal, the compiler knows whether it will fit into a char without losing data and only complains when you use a literal that is too big to fit into a char:

char c = 70000; // compiler error