Java provides many types of operators which can be used according to the need. They are classified based on the functionality they provide. In this article, we will learn about Java Operators and learn all their types.

Agenda

Operators
Basic Rules
Quizzes
Concatenation
Intro to variable

Operators

What are the Java Operators?

Operators in Java are the symbols used for performing specific operations in Java. Operators make tasks like addition, multiplication, etc which look easy although the implementation of these tasks is quite complex.

Types of Operators in Java

There are multiple types of operators in Java all are mentioned below:

Arithmetic Operators
Unary Operators
Assignment Operator
Relational Operators
Logical Operators
Ternary Operator
Bitwise Operators
Shift Operators
instance of operator

1. Arithmetic Operators

They are used to perform simple arithmetic operations on primitive data types.

'*' : Multiplication
/ : Division
% : Modulo
'+' : Addition
– : Subtraction

Example:

// Java Program to implement
// Arithmetic Operators
import java.io.*;

// Drive Class
class Test {
      // Main Function
    public static void main (String[] args) {
          
        // Arithmetic operators
        int a = 10;
        int b = 3;
      
        System.out.println("a + b = " + (a + b));
        System.out.println("a - b = " + (a - b));
        System.out.println("a * b = " + (a * b));
        System.out.println("a / b = " + (a / b));
        System.out.println("a % b = " + (a % b));
          
    }
}

Output

a + b = 13
a - b = 7
a * b = 30
a / b = 3
a % b = 1

2. Unary Operators

Unary operators need only one operand. They are used to increment, decrement, or negate a value.

– : Unary minus, used for negating the values.
+ : Unary plus indicates the positive value (numbers are positive without this, however). It performs an automatic conversion to int when the type of its operand is the byte, char, or short. This is called unary numeric promotion.
++ : Increment operator, used for incrementing the value by 1. There are two varieties of increment operators.
- Post-Increment: Value is first used for computing the result and then incremented.
- Pre-Increment: Value is incremented first, and then the result is computed.
– – : Decrement operator, used for decrementing the value by 1. There are two varieties of decrement operators.
- Post-decrement: Value is first used for computing the result and then decremented.
- Pre-Decrement: The value is decremented first, and then the result is computed.
! : Logical not operator, used for inverting a boolean value.

Example:

// Java Program to implement
// Unary Operators
import java.io.*;

// Driver Class
class Test {
      // main function
    public static void main(String[] args)
    {
        // Interger declared
        int a = 10;
        int b = 10;

        // Using unary operators
        System.out.println("Postincrement : " + (a++));
        System.out.println("Preincrement : " + (++a));

        System.out.println("Postdecrement : " + (b--));
        System.out.println("Predecrement : " + (--b));
    }
}

Output

Postincrement : 10
Preincrement : 12
Postdecrement : 10
Predecrement : 8

3. Assignment Operator

‘=’ Assignment operator is used to assign a value to any variable. It has right-to-left associativity, i.e. value given on the right-hand side of the operator is assigned to the variable on the left, and therefore right-hand side value must be declared before using it or should be a constant.

The general format of the assignment operator is:

variable = value;

In many cases, the assignment operator can be combined with other operators to build a shorter version of the statement called a Compound Statement. For example, instead of a = a+5, we can write a += 5.

+=, for adding the left operand with the right operand and then assigning it to the variable on the left.
-=, for subtracting the right operand from the left operand and then assigning it to the variable on the left.
*=, for multiplying the left operand with the right operand and then assigning it to the variable on the left.
/=, for dividing the left operand by the right operand and then assigning it to the variable on the left.
%=, for assigning the modulo of the left operand by the right operand and then assigning it to the variable on the left.

Example:

// Java Program to implement
// Assignment Operators
import java.io.*;

// Driver Class
class Test {
    // Main Function
    public static void main(String[] args)
    {
        
        // Assignment operators
        int f = 7;
        System.out.println("f += 3: " + (f += 3));
        System.out.println("f -= 2: " + (f -= 2));
        System.out.println("f *= 4: " + (f *= 4));
        System.out.println("f /= 3: " + (f /= 3));
        System.out.println("f %= 2: " + (f %= 2));
        System.out.println("f &= 0b1010: " + (f &= 0b1010));
        System.out.println("f |= 0b1100: " + (f |= 0b1100));
        System.out.println("f ^= 0b1010: " + (f ^= 0b1010));
        System.out.println("f <<= 2: " + (f <<= 2));
        System.out.println("f >>= 1: " + (f >>= 1));
        System.out.println("f >>>= 1: " + (f >>>= 1));
    }
}

Output

f += 3: 10
f -= 2: 8
f *= 4: 32
f /= 3: 10
f %= 2: 0
f &= 0b1010: 0
f |= 0b1100: 12
f ^= 0b1010: 6
f <<= 2: 24
f >>= 1: 12
f >>>= 1: 6

4. Relational Operators

These operators are used to check for relations like equality, greater than, and less than. They return boolean results after the comparison and are extensively used in looping statements as well as conditional if-else statements. The general format is,

variable relation_operator value

Some of the relational operators are-

==, Equal to returns true if the left-hand side is equal to the right-hand side.
!=, Not Equal to returns true if the left-hand side is not equal to the right-hand side.
<, less than: returns true if the left-hand side is less than the right-hand side.
<=, less than or equal to returns true if the left-hand side is less than or equal to the right-hand side.
>, Greater than: returns true if the left-hand side is greater than the right-hand side.
>=, Greater than or equal to returns true if the left-hand side is greater than or equal to the right-hand side.

Example:

// Java Program to implement
// Relational Operators
import java.io.*;

// Driver Class
class Test {
    // main function
    public static void main(String[] args)
    {
        // Comparison operators
        int a = 10;
        int b = 3;
        int c = 5;

        System.out.println("a > b: " + (a > b));
        System.out.println("a < b: " + (a < b));
        System.out.println("a >= b: " + (a >= b));
        System.out.println("a <= b: " + (a <= b));
        System.out.println("a == c: " + (a == c));
        System.out.println("a != c: " + (a != c));
    }
}

Output

a > b: true
a < b: false
a >= b: true
a <= b: false
a == c: false
a != c: true

5. Logical Operators

These operators are used to perform “logical AND” and “logical OR” operations, i.e., a function similar to AND gate and OR gate in digital electronics. One thing to keep in mind is the second condition is not evaluated if the first one is false, i.e., it has a short-circuiting effect. Used extensively to test for several conditions for making a decision. Java also has “Logical NOT”, which returns true when the condition is false and vice-versa

Conditional operators are:

&&, Logical AND: returns true when both conditions are true.
||, Logical OR: returns true if at least one condition is true.
!, Logical NOT: returns true when a condition is false and vice-versa

Example:

// Java Program to implemenet
// Logical operators
import java.io.*;

// Driver Class
class GFG {
      // Main Function
    public static void main (String[] args) {
        // Logical operators
        boolean x = true;
        boolean y = false;
      
        System.out.println("x && y: " + (x && y));
        System.out.println("x || y: " + (x || y));
        System.out.println("!x: " + (!x));
    }
}

Output

x && y: false
x || y: true
!x: false

6. Ternary operator

The ternary operator is a shorthand version of the if-else statement. It has three operands and hence the name Ternary.

The general format is:

condition ? if true : if false

The above statement means that if the condition evaluates to true, then execute the statements after the ‘?’ else execute the statements after the ‘:’.

Example:

// Java program to illustrate
// max of three numbers using
// ternary operator.
public class operators {
    public static void main(String[] args)
    {
        int a = 20, b = 10, c = 30, result;

        // result holds max of three
        // numbers
        result
            = ((a > b) ? (a > c) ? a : c : (b > c) ? b : c);
        System.out.println("Max of three numbers = "
                           + result);
    }
}

Output

Max of three numbers = 30

7. Bitwise Operators

These operators are used to perform the manipulation of individual bits of a number. They can be used with any of the integer types. They are used when performing update and query operations of the Binary indexed trees.

&, Bitwise AND operator: returns bit by bit AND of input values.
|, Bitwise OR operator: returns bit by bit OR of input values.
^, Bitwise XOR operator: returns bit-by-bit XOR of input values.
~, Bitwise Complement Operator: This is a unary operator which returns the one’s complement representation of the input value, i.e., with all bits inverted.

Example

// Java Program to implement
// bitwise operators
import java.io.*;

// Driver class
class GFG {
    // main function
    public static void main(String[] args)
    {
        // Bitwise operators
        int d = 0b1010;
        int e = 0b1100;
        System.out.println("d & e: " + (d & e));
        System.out.println("d | e: " + (d | e));
        System.out.println("d ^ e: " + (d ^ e));
        System.out.println("~d: " + (~d));
        System.out.println("d << 2: " + (d << 2));
        System.out.println("e >> 1: " + (e >> 1));
        System.out.println("e >>> 1: " + (e >>> 1));
    }
}

Output

d & e: 8
d | e: 14
d ^ e: 6
~d: -11
d << 2: 40
e >> 1: 6
e >>> 1: 6

8. Shift Operators

These operators are used to shift the bits of a number left or right, thereby multiplying or dividing the number by two, respectively. They can be used when we have to multiply or divide a number by two. General format-

number shift_op number_of_places_to_shift;

<<, Left shift operator: shifts the bits of the number to the left and fills 0 on voids left as a result. Similar effect as multiplying the number with some power of two.
>>, Signed Right shift operator: shifts the bits of the number to the right and fills 0 on voids left as a result. The leftmost bit depends on the sign of the initial number. Similar effect to dividing the number with some power of two.
>>>, Unsigned Right shift operator: shifts the bits of the number to the right and fills 0 on voids left as a result. The leftmost bit is set to 0.

Example

// Java Program to implement
// shift operators
import java.io.*;

// Driver Class
class GFG {
    // main function
    public static void main(String[] args)
    {
        int a = 10;
    
          // using left shift
        System.out.println("a<<1 : " + (a << 1));
      
        // using right shift
        System.out.println("a>>1 : " + (a >> 1));
    }
}

Output

a<<1 : 20 a>>1 : 5

9. instanceof operator

The instance of the operator is used for type checking. It can be used to test if an object is an instance of a class, a subclass, or an interface. General format-

object instance of class/subclass/interface

Example

// Java program to illustrate
// instance of operator

class operators {
    public static void main(String[] args)
    {

        Person obj1 = new Person();
        Person obj2 = new Boy();

        // As obj is of type person, it is not an
        // instance of Boy or interface
        System.out.println("obj1 instanceof Person: "
                           + (obj1 instanceof Person));
        System.out.println("obj1 instanceof Boy: "
                           + (obj1 instanceof Boy));
        System.out.println("obj1 instanceof MyInterface: "
                           + (obj1 instanceof MyInterface));

        // Since obj2 is of type boy,
        // whose parent class is person
        // and it implements the interface Myinterface
        // it is instance of all of these classes
        System.out.println("obj2 instanceof Person: "
                           + (obj2 instanceof Person));
        System.out.println("obj2 instanceof Boy: "
                           + (obj2 instanceof Boy));
        System.out.println("obj2 instanceof MyInterface: "
                           + (obj2 instanceof MyInterface));
    }
}

class Person {
}

class Boy extends Person implements MyInterface {
}

interface MyInterface {
}

Output

obj1 instanceof Person: true
obj1 instanceof Boy: false
obj1 instanceof MyInterface: false
obj2 instanceof Person: true
obj2 instanceof Boy: true
obj2 instanceof MyInterface: true

Interesting Questions about Java Operators

1. Precedence and Associativity:

There is often confusion when it comes to hybrid equations which are equations having multiple operators. The problem is which part to solve first. There is a golden rule to follow in these situations. If the operators have different precedence, solve the higher precedence first. If they have the same precedence, solve according to associativity, that is, either from right to left or from left to right. The explanation of the below program is well written in comments within the program itself.

public class operators {
    public static void main(String[] args)
    {
        int a = 20, b = 10, c = 0, d = 20, e = 40, f = 30;

        // precedence rules for arithmetic operators.
        // (* = / = %) > (+ = -)
        // prints a+(b/d)
        System.out.println("a+b/d = " + (a + b / d));

        // if same precedence then associative
        // rules are followed.
        // e/f -> b*d -> a+(b*d) -> a+(b*d)-(e/f)
        System.out.println("a+b*d-e/f = "
                           + (a + b * d - e / f));
    }
}

Output

a+b/d = 20
a+b*d-e/f = 219

2. Be a Compiler:

The compiler in our systems uses a lex tool to match the greatest match when generating tokens. This creates a bit of a problem if overlooked. For example, consider the statement a=b+++c; too many of the readers might seem to create a compiler error. But this statement is absolutely correct as the token created by lex is a, =, b, ++, +, c. Therefore, this statement has a similar effect of first assigning b+c to a and then incrementing b. Similarly, a=b+++++c; would generate an error as the tokens generated are a, =, b, ++, ++, +, c. which is actually an error as there is no operand after the second unary operand.

public class operators {
    public static void main(String[] args)
    {
        int a = 20, b = 10, c = 0;

        // a=b+++c is compiled as
        // b++ +c
        // a=b+c then b=b+1
        a = b++ + c;
        System.out.println("Value of a(b+c), "
                           + " b(b+1), c = " + a + ", " + b
                           + ", " + c);

        // a=b+++++c is compiled as
        // b++ ++ +c
        // which gives error.
        // a=b+++++c;
        // System.out.println(b+++++c);
    }
}

Output

Value of a(b+c),  b(b+1), c = 10, 11, 0

3. Using + over ():

When using the + operator inside system.out.println() make sure to do addition using parenthesis. If we write something before doing addition, then string addition takes place, that is, associativity of addition is left to right, and hence integers are added to a string first producing a string, and string objects concatenate when using +. Therefore it can create unwanted results.

public class operators {
    public static void main(String[] args)
    {
        int x = 5, y = 8;

        // concatenates x and y as
        // first x is added to "concatenation (x+y) = "
        // producing "concatenation (x+y) = 5"
        // and then 8 is further concatenated.
        System.out.println("Concatenation (x+y)= " + x + y);

        // addition of x and y
        System.out.println("Addition (x+y) = " + (x + y));
    }
}

Output

Concatenation (x+y)= 58
Addition (x+y) = 13

Advantages of Operators in Java

The advantages of using operators in Java are mentioned below:

Expressiveness: Operators in Java provide a concise and readable way to perform complex calculations and logical operations.
Time-Saving: Operators in Java save time by reducing the amount of code required to perform certain tasks.
Improved Performance: Using operators can improve performance because they are often implemented at the hardware level, making them faster than equivalent Java code.

Disadvantages of Operators in Java

The disadvantages of Operators in Java are mentioned below:

Operator Precedence: Operators in Java have a defined precedence, which can lead to unexpected results if not used properly.
Type Coercion: Java performs implicit type conversions when using operators, which can lead to unexpected results or errors if not used properly.

Basic Rules

Statements end with a semicolon ( ; )
JAVA is Case Sensitive.
In order to print text, we use double quotes ( " " )
{}, (), " " --> All of these are in pairs.
Comments →
- Single-line comments start with two forward slashes ( // ). Any text between // and the end of the line is ignored by Java (will not be executed).
- Multi-line comments start with /* and ends with */. Any text between /* and */ will be ignored by Java.
System.out.print(); → Just type the output
System.out.println(); → Just type the output and press Enter cursor moves to the next line

Quizzes

Now, let's check how much they remember from the last class with the help of quizzes.

Q1. What will be output for this ?

System.out.print("Welcome in playground")

Choices

Welcome Home
Welcome in playground
Error
All the options are correct

Q2. What will be output for this ?

system.out.print("Hi Everyone");

Choices

Hi Everyone
Bye Everyone
Error
Welcome Everyone

Q3. What will be output for this ?

System.ouT.print("Hi Guys");

Choices

Hi Guys
Bye Guys
Error
Welcome Guys

Q4. What will be output for this ?

System.out.print(Good Morning Everyone);

Choices

Good Morning Everyone
Good Afternoon Everyone
Error
Good Night Everyone

Q5. What will be output for this ?

System.out.print('Happy Thursday');

Choices

Happy Thursday
Sad Thursday
Error
All the options are correct

Q6. What will be output for this ?

System.out.print(10 + 20);

Choices

30
10+20
Error

Q7. What will be output for this ?

System.out.print(10 - 25);

Choices

-15
15
10
Error

Q8. What will be output for this ?

System.out.println("Hello");
System.out.print("World);

Choices

Hello
World
HelloWorld
Error
inky pinky po

Q9. What will be output for this ?

System.out.print("Hello");
System.out.println("World");

Choices

Hello
World
HelloWorld
Error
inky pinky po

Q10. What will be output for this ?

System.out.println("Hello");
System.out.print("World");
System.out.println("Welcome")

Choices

Hello
World
Welcome
HelloWorldWelcome
Error
Hello
WorldWelcome

Q11. What will be output for this ?

System.out.printLN("Hello");
System.out.println("World);

Choices

Hello
World
HelloWorld
Error
inky-pinky-po

Q12. What will be output for this ?

Which of the follwing are operators?

Choices

Q13. What is the outup.?

10+30
In the given expression choose the operands.

Choices

(+)
10
30
Both 10 and 30

Explanation of Quiz : Operator : + Operands : 10 and 30

Explain using one more example if needed.

Numbers -> 2 types

Decimal -> Numbers that have Decimal point Ex. 4.67, 0.986, 20.73, 2.0
Non Decimal / Integer -> Any +ve, -ve or 0 Ex. 7, -30, 0, -7

Q14. What will be output for this ?

System.out.print(5 + 8);

Choices

Q15. What will be output for this ?

System.out.print(5 - 8);

Choices

-1
-2
-3
-4

Q16. What will be output for this ?

System.out.print(5 * 8);

Choices

Q17 What will be output for this ?

System.out.print(8 / 2);

Choices

Q18. What will be output for this ?

System.out.print(10 / 3);

Choices

3.3333
3
Error
None of them

Explanation : In calculator, 10 / 3 = 3.33333. But in JAVA, we get 3 (round-off).

Rule : In JAVA, when you divide (/) integers we only get quotient.

Q19. What will be output for this ?

System.out.print(24 / 9);

Choices

1
2.54
2
3

Q20. What will be output for this ?

System.out.print(3 / 6);

Choices

1
0
Error

Q21. What will be output for this ?

System.out.print(24 / 0);

Choices

Infinite
24
0
Error

Rule: Division of integers by zero is not possible in JAVA

Q22. What will be output for this ?

System.out.print(6 * 7 / 6);

Choices

7
6
None of them
All of them

Explanation:

But we cannot have two answers for the same expression. So, there must be some rules in place to get the output.

Priority in Operators:

Rank 1 : ()
Rank 2 : * , /
Rank 3 : + , -

Few important rules of doing operations

Rule 1 :
If we have same priority operators, whichever comes first from left to right that will be evaluated first.
Rule 2 :
If we have different priority operators, whichever has highest priority that will be evaluated first.

Explanation: Here, * and / have same priority. Because * comes first we will evaluate 6 * 7 will be evaluated first. => 6 * 7 / 6 => 42 / 6 => 7

Q1. What will be output for this ?

System.out.print(4 + 3 * 6 - 7 / 2);

Choices

Explanation: Between * and / we will be evaluating multiply first and then divide. => 4 + 3 * 6 - 7 / 2 => 4 + 18 - 7 / 2 => 4 + 18 - 3 => 22 - 3 => 19

Q2. What will be output for this ?

System.out.print(5 + 2 * 3);

Choices

21
17
11
Error

Explanation: Here, * has higher priority. => 5 + 2 * 3 => 5 + 6 => 11

Q3. What will be output for this ?

System.out.print(5 + 15 / 5 + 6 * 3);

Choices

30
26
11
Error

Explanation: => 5 + 15 / 5 + 6 * 3 => 5 + 3 + 6 * 3 => 5 + 3 + 18 => 8 + 18 => 26

Q4. What will be output for this ?

System.out.print(7 - 2 * 4 + 18 / 3);

Choices

15
5
30
Error

Explanation: => 7 - 2 * 4 + 18 / 3 => 7 - 8 + 18 / 3 => 7 - 8 + 6 => -1 + 6 => 5

Q5. What will be output for this ?

System.out.print(3 * 4 / 2 + 7 + 3 - 4 / 2);

Choices

21
14
11
Error

Explanation: => 3 * 4 / 2 + 7 + 3 - 4 / 2 => 12 / 2 + 7 + 3 - 4 / 2 => 6 + 7 + 3 - 4 / 2 => 6 + 7 + 3 - 2 => 13 + 3 - 2 => 16 - 2 => 14

Q6. What will be output for this ?

System.out.print(5 + 2 * 4 + 8 - 6 + 12 / 4);

Choices

25
18
16
Error

Explanation: => 5 + 2 * 4 + 8 - 6 + 12 / 4 => 5 + 8 + 8 - 6 + 12 / 4 => 5 + 8 + 8 - 6 + 3 => 13 + 8 - 6 + 3 => 21 - 6 + 3 => 15 + 3 => 18

Q7. What will be output for this ?

System.out.print( (5 + 2) * 3 );

Choices

21
17
11
Error

Explanation: => (5 + 2) * 3) => 7 * 3 => 21

Q8. What will be output for this ?

System.out.print("Hello" + "World");

Choices

Hello
World
HelloWorld
Error
I'm sleeping, Don't Disturb

Explanation:

Rule: With + operator, If one Operand is text then we concatenate both Operands

Q9. What will be output for this ?

System.out.print("Hi" + "Students" + "Namaste");

Choices

HiStudentsNamaste
HelloEveryone
Error
I'm Angry :(

Explanation: => "Hi" + "Students" + "Namaste" => "HiStudents" + "Namaste" => "HiStudentsNamaste"

Q10. What will be output for this ?

System.out.print("Hi" + " " + "Namaste");

Choices

Hi Namaste
HiNamaste
Error
Namaste Hi

Explanation: => "Hi" + " " + "Namaste" => "Hi " + "Namaste" => "Hi Namaste"

Q11. What will be output for this ?

System.out.print("Hi" * "Guys");

Choices

HiGuys HiGuys HiGuys
Error
abcdefghijklmnopqrstuvwxyz
Hi Guys

Explanation: We cannot use * with text operand.

Rule: With text operand, only + operator can be used. Any other operator gives error.

Q12. What will be output for this ?

System.out.print("WelcomeHome" - "Home");

Choices

Welcome
WelcomeHome-Home
Home
Error

Explanation: We cannot use - with text operand.

Q13. What will be output for this ?

System.out.print("Hello" + 3);

Choices

Hello
Hello3
Error
HelloHelloHello

Explanation: Operator: + Operands: "Hello" -> text 3 -> number Since, one operand is text, we concatenate both operands.

Q14. What will be output for this ?

System.out.print("Hello" + 3 + 4);

Choices

Hello
Hello34
Hello7
Error

Explanation: Since, both operators are + and have same priority we will evaluate from left to right => "Hello" + 3 + 4 => "Hello3" + 4 => "Hello34"

Q15. What will be output for this ?

System.out.print("Hello" + 10 + "World");

Choices

HelloWorld
Hello10World
Hello10
Error

Explanation: => "Hello" + 10 + "World" => "Hello10" + "World" => "Hello10World"

Q16. What will be output for this ?

System.out.print(10 + "Welcome");

Choices

Welcome10
10Welcome
Welcome 10 times
inky pinky po

Explanation: => 10 + "Welcome" => "10Welcome"

Q17. What will be output for this ?

System.out.print(10 + 20 + "WakeUp" + 3 + 2);

Choices

1020WakeUp32
1020WakeUp5
30WakeUp5
30WakeUp32

Explanation: => 10 + 20 + "WakeUp" + 3 + 2 => 30 + "WakeUp" + 3 + 2 => "30WakeUp" + 3 + 2 => "30WakeUp3" + 2 => "30WakeUp32"

Q18. What will be output for this ?

System.out.print("HiGuys" * 2);

Choices

HiGuys*2
HiGuys2
HiGuysHiGuys
Error

Explanation: We cannot use * operator with text operand

Q19. What will be output for this ?

System.out.print(10 + 20 + "WakeUp" + 3 * 2);

Choices

1020WakeUp32
30WakeUp32
Error
30WakeUp6

Explanation:

=> 10 + 20 + "WakeUp" + 3 * 2 => 10 + 20 + "WakeUp" + 6 => 30 + "WakeUp" + 6 => "30WakeUp" + 6 => "30WakeUp6"

Q20. What will be output for this ?

System.out.print(10 + "Hello" * "World" + 3);

Choices

10HelloWorld3
10HelloWorldWorldWorld3
Error
Good Morning :)

Explanation: We cannot use * operator with text operand

Q21. What will be output for this ?

System.out.print(10 + "WelcomeHome" - "Home" + 3);

Choices

10Welcome3
10WelcomeHomeHome3
Error
Good Morning :)

Explanation: We cannot use - operator with text operand

Q22. Predict the output for the following code:

System.out.println(10 + 20 + "Hello");

Choices

1020Hello
30Hello
Hello1020
Hello Hello Hello Explanation 10 + 20 = 30, Now when string is concatenated then 30 becomes as string "30" so the answer is "30Hello".

Introduction to Variables

Start with that numbers are of two types:

Non-Decimal / Integers
Decimals

Story : Assume we have a container storing water in it And then explain the three factors of container that are : Type, Name and Value

After that take a container to store integers and explain the same three factors.

In programming, containers are known as variables.

Creating a variable:

Q1. What will be output for this ?

Create a variable of type int and give name as num and assign 34 in it.

Choices

num = 34
int num = 34;
int 34 num
num int = 34

Q2. What will be output for this ?

int val = 30;
System.out.println(val);

Choices

val
30
Error
Don't Select me, I'm wrong option

Explanation: The value of variable val is 30.

Rule : Whenever we use variable name, the value of that variable is used.

Q3. What will be output for this ?

int a = 10;
int b = 20;
System.out.println(a + b);

Choices

ab
30
Error
Keep focus on the above option, I am wrong

Q4. What will be output for this ?

int a = 10;
int b = 20;
System.out.println("Sum of Number is " + a + b);

Choices

Sum of Number is 30
Sum of Number is 1020
Error
Above Options, Not me :)

Explanation:

Here, both operators are + and have same priority. Hence, the exppression will be evaluated from left to right. => "Sum of Number is " + a + b => "Sum of Number is " + 10 + 20 => "Sum of Number is 10" + 20 => "Sum of Number is 1020"

Q5. What will be output for this ?

int a = 10;
int b = 20;
System.out.println("Product of Number is " + a * b);

Choices

Product of Number is 1020
Product of Number is 200
Error
Again Above Options, Not me :)

Explanation: Here, * has highest priority. So, a * b will be evaluated first. => "Product of Number is " + a * b => "Product of Number is " + 10 * 20 => "Product of Number is " + 200 => "Product of Number is 200"

Summary

In Java, when we divide ( / ) integers we only get quotient.
We cannot divide integers by 0, we get error.
Priority of Operators :
- Rank 1 : ()
- Rank 2 : * , /
- Rank 3 : + , -
When two operators of different priority are there, we evaluate the one with higher priority first.
When two operators of same priority are there, we evaluate the one which comes first from left to right.
With + operator, if one of the operand is text then we concatenate both the operands.
Creating a variable:
- type name = value;
- Way 1 :
  - int x = 30;
- Way 2 :
  - int y; y = 40;
When we use variable name, we use its value.

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Start with that numbers are of two types:

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Rahul Aher