java--operator Issues

5,number
All wrapper classes (Integer, Long, Byte, Double, Float, short) are subclasses of the abstract class number.

6.
y=x++ + ++x can be seen as y= (x + +) + (++x), when the + + or--and other variables are calculated,
X + + indicates that the first operation, then self-increment, ++x the first self-increment and then participate in the operation

The 7.byte type is multiplied by the data of type byte and the value is type int must be cast
Example: Byte a1=1,a2=3; int a3= (int) a1*a2;

java--operator Issues