Output and Basic Data Types¶

Agenda¶

Revise Initial Rules
Evaluating Expression
Quizzes
Concatenation
Intro to variable

Section 2.1 (Revision)¶

end statements with a semicolon ( ; )
JAVA is case sensitive. -> System, system are considered different
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]

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

Question¶

What will be output for this ?

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

Choices¶

Welcome Home
Welcome in playground
Error
All the options are correct

Question¶

What will be output for this ?

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

Choices¶

Hi Everyone
Bye Everyone
Error
Welcome Everyone

Question¶

What will be output for this ?

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

Choices¶

Hi Guys
Bye Guys
Error
Welcome Guys

Question¶

What will be output for this ?

System.out.print(Good Morning Everyone);

Choices¶

Good Morning Everyone
Good Afternoon Everyone
Error
Good Night Everyone

Question¶

What will be output for this ?

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

Choices¶

Happy Thursday
Sad Thursday
Error
All the options are correct

Question¶

What will be output for this ?

System.out.print(10 + 20);

Choices¶

30
10+20
Error

Question¶

What will be output for this ?

System.out.print(10 - 25);

Choices¶

-15
15
10
Error

Question¶

What will be output for this ?

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

Choices¶

Hello
World
HelloWorld
Error
inky pinky po

Question¶

What will be output for this ?

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

Choices¶

Hello
World
HelloWorld
Error
inky pinky po

Question¶

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

Question¶

What will be output for this ?

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

Choices¶

Hello
World
HelloWorld
Error
inky-pinky-po

Question¶

What will be output for this ?

Which of the follwing are operators?

Choices¶

Question¶

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
Note: In today's class, we will only discuss Integers.

Very Basic expression on simple maths. Time of the quiz is 20sec.

Question¶

What will be output for this ?

System.out.print(5 + 8);

Choices¶

11
12
13
14

Question¶

What will be output for this ?

System.out.print(5 - 8);

Choices¶

-1
-2
-3
-4

Question¶

What will be output for this ?

System.out.print(5 * 8);

Choices¶

30
32
40
42

Question¶

What will be output for this ?

System.out.print(8 / 2);

Choices¶

3
4
5
6

Question¶

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

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

Question¶

What will be output for this ?

System.out.print(24 / 9);

Choices¶

1
2.54
2
3

Question¶

What will be output for this ?

System.out.print(3 / 6);

Choices¶

1
0
Error

Question¶

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

Question¶

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

Question¶

What will be output for this ?

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

Choices¶

16
17
18
19

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

Question¶

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

Question¶

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

Question¶

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

Question¶

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

Question¶

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

Question¶

What will be output for this ?

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

Choices¶

21
17
11
Error

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

Question¶

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

Question¶

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"

Question¶

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"

Question¶

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.

Question¶

What will be output for this ?

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

Choices¶

Welcome
WelcomeHome-Home
Home
Error

Explanation: We cannot use - with text operand.

Question¶

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.

Question¶

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"

Question¶

What will be output for this ?

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

Choices¶

HelloWorld
Hello10World
Hello10
Error

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

Question¶

What will be output for this ?

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

Choices¶

Welcome10
10Welcome
Welcome 10 times
inky pinky po

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

Question¶

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"

Question¶

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

Question¶

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"

Question¶

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

Question¶

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

Question¶

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".

Section 2.3 (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:¶

Question¶

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

Question¶

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.

Question¶

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

Question¶

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"

Question¶

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"

Section 2.4 (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.