Variables

 Javada iki cur varialbe var: primitive type and reference(complex type, reference type)

Primitive

1. boolean - 1 bit. true or false. By default false.

2. byte - 8 bit integral value. 0

3. short - 16 bit integral value. 0

4. int - 32 bit integral value. 0

5. long - 64 bit integral value. 0

6. float - 32 bit floating-point value. 0.0f

7. double - 64 bit floating-point value. 0.0f

8. char - 16 bit Unicode value. '\u0000'

variable(identifier) - lar istenilen herf, $, _  bawlaya biler. variable adinda . istifade oluna bimez.

 

Mes: float f = 4; float n = 4,3F; long k = 3L; double s = 3; double d = 3.6;

Ikilik say sistemi: 0b veya 0B ile bawlayir. 

Sekkizlik say sistemi: 0 ile bawlayir.

Onaltiliq say sistemi: 0x ile bawlayir. 

Declaration: boolean b;

Initialization: b = true;

Definition: int i = 6; Definition = declaration + initialization

Unicode elementleri '\uxxxx' weklinde ifade edilir.  'x' 16-liq say sistemindeki (hexadecimal) reqemlerdir. Yeni bir Unicode kodu 4 eded 4 bitlik reqemlerden emele gelir: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F] yeni ['\u0000' - '\uffff']

"_" - iki reqem arasinda iwlenilir. Bawlangicda ve sonda, noqtenin yaninda, "f", "F", "d", "D", "l", "L" yaninda iwlene bilmez. 

public class Main {
    public static void main(String[] args) {
        String a = "10_0";
        Integer b = Integer.valueOf(a);
        System.out.println(a);
        System.out.println(b);
    }
}

Bu wekilde cevirme apara bilmerik.

Primitiv deyiwenlerle referans deyiwenlerin ferqi:

public class Main {
    public static void main(String[] args) {
        int i = 5;
        int j = i;
        i = 7;
        System.out.println(i);
        System.out.println(j);

        String s1 = new String("a");
        String s2 = new String("b");
        String temp = s1;
        s1 = s2;
        s2 = temp;
    }
}

Roles of variables.
1. Instance or object variables. 2. Class variables. 3. Local variables.
1. Instance of object variables - identify, represent object.
2. Local variables - method parameters, inside blocks of methods, inside blocks. Local variab-
les are not part of the object. Sometimes they are called temporary variables or stack variab-
les.

local variable - lari initialize etmek lazimdir.