Identifiers, Literals, Operators and Separators in Java Programming Language

Here is a clear introduction (exam-ready + student-friendly) to Identifiers, Literals, Separators, and Operators in programming (especially Java/C-style languages).

🔹 Identifiers

An identifier is the name given to a variable, method, class, array, or any user-defined item in a program. It helps identify these elements uniquely.

✔ Rules for Identifiers (Java)

• Must begin with a letter (A–Z or a–z), underscore (_), or dollar sign ($)
• Cannot start with a number
• Cannot be a reserved keyword
• Case-sensitive (total and Total are different)
• No spaces allowed

Examples

✔ Valid Identifiers

int age;
double totalMarks;
String studentName;
int _count;

❌ Invalid Identifiers

int 2value;      // starts with number
int total marks; // contains space
int class;       // keyword

👉 Identifiers make programs readable and meaningful.

🔹 Literals

         A literal is a fixed value written directly in the program. It does not change during execution. It is nothing but a synthetic representation of boolean, character, numeric, or string data

1.      Integral Literals

2.      Floating-Point Literals

3.      Char Literals

4.      String Literals

5.      Boolean Literals

6.      Null Literals

✔ Types of Literals (Java)

1. Integer Literal

Integer Literal doesn’t have the prefix characters.

Example: int x = 108;

2.  Octal Literal

Starts with ‘0’ (Zero)

Example: int x = 0745;

3.  Hexa decimal Literal:

Starts with ‘0X’ (zero & X)

Example: int x = 0X123Fadd;

4.  Binary Literal:

starts with zero and b

Example:int x = 0b1011;

Sample Program

public class Test_int_literal

{

public static void main(String[] args)

{

// decimal-form literal

int a = 101;

// octal-form literal

int b = 0100;

// Hexa-decimal form literal

int c = 0xFace;

// Binary literal

int d = 0b1111;

System.out.println(a);

System.out.println(b);

System.out.println(c);

System.out.println(d);

}}

Output

5. Floating-Point Literal

Floating-point literals are literal in programming that represent real numbers (numbers with a decimal point) using the floating-point notation. 

 

Number N1= 89d;

Number N2= 3.14159e0; // it is in scientific notation. After ‘e’ is //power of 10 (10⁰)

 

Number N3= 1.0e-6D; //it is in scientific notation 1.0 * 10^-6

 

float f = 3.14f;
double d = 12.56;

 

public class Test_decimal_literal {

public static void main(String[] args)

{

// decimal-form literal

float a = 101.230f;

// It also serves the purpose of a decimal literal

float b = 0123.222f;

// Hexa-decimal form

float c = 0x1.23p4f; 

double d = 0xA.BCp2; 

float e = 0x123p0f;

System.out.println(a);

System.out.println(b);

System.out.println(c);

} }

Output:

6. Character Literal

Character (Char) literals have the type char and are an unsigned integer primitive type. They are constant value character expressions in the Java program. These are sixteen-bit Unicode characters that range from 0 to 65535. Char literals are expressed as a single quote, a single closing quote, and the character in Java.    

 

Example.

char ch = 062;

char ch = ‘\n’;

char ch = ‘\u0061’;

char ch = 'A';
char symbol = '#';

 

public class Test {

public static void main(String[] args)

{

char ch = 'a'; // single character literal within a single quote

char b = 0771; // It is an Integer literal with an octal form

char c = '\u0061'; // Unicode representation

System.out.println(ch);

System.out.println(b);

System.out.println(c);

// Escape character literal

System.out.println("\" is a symbol");

}}

Output

7. String Literal

A sequence of (zero or more including Unicode characters) characters within double quotes is referred to as string literals. 

 

For example,

String s = “Hello”;

String name = "Ravi";

Some character, its ACII and Unicode values

 

Name	Character	ASCII	Hex
Single quote	\’	39	0x27
Double quotes	\”	34	0x22
Carriage control	\r	13	0xd
Backlash	\\	92	0x5c
Newline	\n	10	0x0a
NUL character	\0	0	0x00
Backspace	\b	8	0x08
TAB	\t	9	0x09

 

class Test_string_literals{

public static void main(String s[])

{

   String s1="Hello";

   String s2="Madam or Ma\'dam";

   String s3="Dear Madam\\Sir,";

   String s4="Hi! \n Bye..";

   String s5="Sno\tName";

   System.out.println("s1 -->"+s1);

   System.out.println("s2 -->"+s2);

   System.out.println("s3 -->"+s3);

   System.out.println("s4 -->"+s4);

   System.out.println("s5 -->"+s5);

}

}

Output:

 

8.      Boolean Literal

 Boolean literals allow only two values and thus are divided into two literals:

 True: it represents a real boolean value

False: it represents a false boolean value 

 

For example, 

boolean b = true;

boolean d = false;

boolean flag = true;

🔹 Separators

Separators are symbols used to separate program elements and define structure.

Symbol of Separator	Name of Separator	Definition
;	Semicolon	A semicolon as a separator is used to mark the end of the statement in java. Whenever  we encounter a semicolon after a statement, it means that the statement has ended and the next statement is a different one.
()	Parentheses	Parentheses are used to define the parameters of the methods in java. We use parentheses while typecasting also. Parentheses are also the most commonly used for containing the expressions in the if-else statements.
{}	Braces	Braces are used to define a code block. They are also used to define the scopes of variables. We often use braces for depicting the self-initialized arrays.
[]	Brackets	Brackets are used to declare an array in java.
.	Period	Period is used to distinguish the package names from sub-packages. They are also used to distinguish a variable from a reference variable.
,	Comma	It is used to select a field from an object. We often declare the variables in a single line. The comma is used here to distinguish these variable names from each other.
:	Colon	Colon is used to create a method reference. It is also used for the constructor reference. We often use colons after labels.

✔ Example

int a = 10, b = 20;
if (a < b) {
    System.out.println(a);
}

👉 Separators organize the program and make it syntactically correct.

🔹 Operators

An operator is a symbol that performs an operation on one or more operands (values or variables).

✔ Types of Operators

Operator Type	Category	Precedence
Unary	Postfix	expr++ expr--
	Prefix	++expr --expr +expr -expr ~ !
Arithmetic	multiplicative	* / %
	additive	+ -
Shift	shift	<< >> >>>
Relational	comparison	< > <= >= instanceof
	equality	== !=
Bitwise	bitwise AND	&
	bitwise exclusive OR	^
	bitwise inclusive OR	|
Logical	logical AND	&&
	logical OR	||
Ternary	ternary	? :
Assignment	assignment	= += -= *= /= %= &= ^= |= <<= >>= >>>=

 1. Arithmetic Operators

Perform mathematical operations.

Operator	Meaning
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus

int sum = a + b;

 2. Relational Operators

Compare values and return true/false.

Operator	Meaning
==	Equal to
!=	Not equal
>	Greater than
<	Less than
>=	Greater or equal
<=	Less or equal

 3. Logical Operators

Combine conditions.

Operator	Meaning
&&	AND
!	NOT

 4. Assignment Operators

Assign values to variables.

int x = 5;
x += 2;   // x = x + 2

 5. Increment / Decrement Operators

Increase or decrease value by 1.

x++;  // increment
x--;  // decrement

 Twisted interview questions

Twisted interview questions

int x = 5;
int y = x++ + ++x;
System.out.println(y); 

Output: 12

 

int a = 1;

int b = a++ + a++ + ++a;

System.out.println(b); 

Output: 7

 

int x = 0;

if (true || ++x > 0) { }

System.out.println(x); 

Output: 0

 

int x = 0;

if (true | ++x > 0) { }

System.out.println(x);                              1

int x = 5;

x = x++;

System.out.println(x);

Output: 5

 

String s1 = "java";
String s2 = "java";
System.out.println(s1 == s2);

Output: True

 

System.out.println("5 + 5 = " + 5 + 5);

System.out.println("5 + 5 = " + (5 + 5));

Output:

55

10

int x = 5;
System.out.println(x > 2 ? x < 4 ? 10 : 20 : 30);    

Output:

20

 

System.out.println(10 / 0);

System.out.println(10.0 / 0);

Output     

Runtime Error

Infinity

 

System.out.println(1 << 3 + 1);                    

Output: 16

System.out.println(true ^ false);
System.out.println(true ^ true);                   

Output: true
false

System.out.println(-10 % 3);                       

Output: -1