Method overloading : Same class , Same method name , Different parameters ( The number is different. , Different types , Different order ), Determine whether to overload , Just look at the method name and parameters , Nothing to do with the return value .

IDEA View the method source code :Crtl + Left mouse button

Hexadecimal said

Java The default value is decimal

Binary system : The value is preceded by 0b start ,b It can be in both case

octal : The value is preceded by 0 start

Hexadecimal : The value is preceded by 0X start ,x It can be in both case

Binary fast to decimal :8421 code

Binary fast to octal : Binary number 3 One by one , Work it out and put it together

Binary fast to hexadecimal : Binary number 4 One by one , Work it out and put it together

The complement of positive numbers is the same

The inverse of a negative number : The sign bits remain the same , The rest of the bits are reversed

A negative complement : At the end of the inverse +1

<< Signed shift left operator : The binary bit moves to the left , The left sign bit is discarded , Right side use 0 A filling . A few places to the left , It's times 2 To the powers of

Signed shift right operator : The binary bit moves to the right , Use sign bits to complement . Move a few to the right , Is divided by 2 To the powers of

Unsigned shift right operator : No matter the sign bit is 0 still 1, It's all used 0 Fill in the space .

Class composition : Attributes and behaviors

Member variables : Variables outside methods in a class , There are default initialization values

local variable : Variable in method , Including formal parameters , No default initialization value

private keyword : Permission modifier , You can modify members , characteristic : Can only be accessed in this class .

this: Identify member variables ( When a local variable has the same name as a member variable ,java Will use the principle of proximity )

this Represents the object reference of the class , Method is called by which object ,this On behalf of the object

Construction method : Called when an object is created , Call once , Execute the construction method once ; Constructors cannot be called manually .

The method name is the same as the class name , The case should also be consistent

no return value , even void either

No specific return value ( Not by return Return results )

If no constructor is written in the class , The system will provide a parameterless construction method

JavaBean class : Encapsulated data

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