Java vs C++ static

Static fields and methods have the same functionality in Java and C++. However, the syntax is slightly different. 

In C++, you use the :: operator to access a static field or method outside its scope, such as Math::PI.

The term "static" has a curious history. 

• At first, the keyword static was introduced in C to denote local variables that don't go away when a block is exited. In that context, the term "static" makes sense: the variable stays around and is still there when the block is entered again. 
• Then static got a second meaning in C, to denote global variables and functions that cannot be accessed from other files. The keyword static was simply reused, to avoid introducing a new keyword. 
• Finally, C++ reused the keyword for a third, unrelated, interpretation—to denote variables and functions that belong to a class but not to any particular object of the class. That is the same meaning that the keyword has in Java.

Variables

Variables are temporary data holders. Variable names are identifiers. Variables are declared with a datatype. Java is a strongly typed language as the variable can only take a value that matches its declared type. This enforces good programming practice and reduces errors considerably. When variables are declared they may or may not be assigned or take on a value (initialized). Examples of each of the primitive datatypes available in Java are as follows:

byte x,y,z;             /* 08bits long, not assigned, multiple declaration */
short numberOfChildren; /* 16bits long */
int counter;            /* 32bits long */
long WorldPopulation;   /* 64bits long */

float pi;               /* 32bit single precision */
double avagadroNumber;  /* 64bit double precision */
boolean signal_flag;    /* true or false only */
char c;                 /* 16bit single Unicode character */

Constant variables
Variables can be made constant or read only by prepending the modifier final to the declaration. Java convention uses all uppercase for final variable names.

Local Variables
Local variables (also known as automatic variables) are declared in methods and in code blocks. The automatic variables are not automatically initialized.
A java programmer should explicitly initialize them before first use. These are automatically destroyed when they go out of scope.

Field Variables and Local Variables Field variables are variables that are declared as members of classes. Local variables, also referred to as automatic variables, are declared relative to (or local to) a method or constructor. <

Automatic Initialization Note
Field variables and the elements of arrays are automatically initialized to default values. Local variables are not automatically initialized. Failure to initialize a local variable results in a compilation error.

Primary or primitive data types in java

There are 4 primary classes of primary data types in java
Integers
Floats
Boolean
Characters
 There are eight primitive types in Java. Four of them are integer types; two are floating-point number types; one is the character type char, used for code units in the Unicode encoding schem; last 1 is boolean.

Default Values for various data types.

Literals

Literal constants are values that do not change within a program. Numeric constants default to integer or double unless a suffix is appended. Note that a character can be represented by an ASCII equivalent. The literal types are:

Boolean: true, false Character: 'c', '\f' String: "Fred", "B and E" Null: null

Integer: 5, 0xFF (hexadecimal)      073 [leading zero] (octal), 5l (long), 0xFFlD (hex) Floating Point: 2.543, -4.1E-6 (double)      2.543f, 8e12f (float)

Note: Do not use leading zeros to format integers as this can cause an unintended octal meaning. Use spaces instead!
Escape (aka backslash) sequences are used inside literal strings to allow print formatting as well as preventing certain characters from causing interpretation errors. Each escape sequence starts with a backslash. The available sequences are:

Seq	Usage	Seq	Usage
\b	backspace	\\	backslash
\f	formfeed	\"	double quote
\n	newline	\'	single quote
\r	carriage return	\###	Octal encoded character
\t	horizontal tab	\uHHHH	Unicode encoded character