Example
static void testNumericPromotion() {
char char1 = 1, char2 = 2;
short short1 = 1, short2 = 2;
int int1 = 1, int2 = 2;
float float1 = 1.0f, float2 = 2.0f;
// char1 = char1 + char2; // Error: Cannot convert from int to char;
// short1 = short1 + short2; // Error: Cannot convert from int to short;
int1 = char1 + char2; // char is promoted to int.
int1 = short1 + short2; // short is promoted to int.
int1 = char1 + short2; // both char and short promoted to int.
float1 = short1 + float2; // short is promoted to float.
int1 = int1 + int2; // int is unchanged.
}