Hands on the brain

One

An enumeration type is a reference type, and the enumeration does not belong to the original data type, and each of his specific values refers to a specific object. The same value refers to the same object.

You can use the ' = = ' and Equals () methods to directly compare the values of the enumeration variables, in other words, the result of the "= =" and the Equals () methods are equivalent for variables of the enumerated type.

Two

Each variable has a corresponding scope and leaving this scope variable will no longer be valid. Two scopes have different names for the same variable, and do not cause conflicts.

publicclassqq {

     private static int code= 24 ;

     public static void main(String[] args) {

         int code=2 ;

         System.out.println(code);

     }

}The result of the output is 23. byte: 1 bytes -128~127 Short: 2 bytes -2^15~2^15-1 int: 4 bytes -2^31~2^31-1 Long: 8 bytes -2^63~2^63-1 Boolean: 1 bytes True False (cannot be replaced in Java by 0 or not 0) float: 4 bytes -3.403e38~3.403e38 Double: 8 bytes -1.798e308~-4.9E324 Char: 2 bytes ' \u0000 ' ~ ' \uffff ' (16 binary, converted to 0~65535) (1 bytes equals 8 bits) four

Output Result:

x+y=100200

300=x+y

Because +x+y indicates that only the values of X and Y are output, x+y represents the value of the output x+y.

Hands on the brain