JAVA

• How do python programmers start learning Python?

Python shell : That's why Python is easy to learn.

• From Java 9: Java is equally easy to learn - JShell

. Java REPL(Read Eval Print Loop)

. Type in one line of code and see the output.

. Makes learning fun (Make a mistake and it immediately tells you whats wrong!)

. All great programmers make use of JShell.

Multiplication Table - Step By Step

. How to break it down?

. Where do we start?

. Calculate 5 * 5

. Print 5 * 5 = 25

. Do this 10 times

• Run jshell :-

C:\Users\Vinay Sharma>jshell
| Welcome to JShell -- Version 23.0.1
| For an introduction type: /help intro

jshell> 5 X 5
| Error:
| ';' expected
| 5 X 5
| ^
| Error:
| not a statement
| 5 X 5
| ^
| Error:
| ';' expected
| 5 X 5
| ^

It is the wrong operater we are using here to multiply, we have to use * for multiply.

ex:-

jshell> 5 * 5
$1 ==> 25

jshell> 5 * 10
$2 ==> 50

Terminology

Here * is an multiplication operator.
5 and 5 are operands.
5 * 5 is an expresssion.

• Here are more examples listed below:

jshell> 5 10
$3 ==> 15

jshell> 5 - 10
$4 ==> -5

jshell> 10/2
$5 ==> 5

• There is an another operator modulus, The modulus operator (%) calculates the remainder of a division.

For ex:-

jshell> 9 % 2
$6 ==> 1 (here 1 is reminder)

jshell> 8 % 2
$7 ==> 0

Here are some more expressions using multiple operators.

ex:-

jshell> 5 5 5
$8 ==> 15

jshell> 5 10 -15
$9 ==> 0

jshell> 5 * 5 5
$10 ==> 30

jshell> 5 * 15 / 3
$11 ==> 25

Task

1. Write an expression to calculate number of minute a day.
2. write an expression to calculate number of seconds in a day.

Ans1. jshell> 24 * 60
$12 ==> 1440

Ans2. jshell> 24 * 60 * 60
$13 ==> 86400

10th Jan

• If we want an exact value in decimal

ex:-

jshell> 5 / 2
$14 ==> 2

jshell> 5.0 / 2.0
$15 ==> 2.5

Here 5.0 is a decimal constant, so to get the exact value we are using it.

• If we divide decimal constant or floating point with a integer, we get the decimal constant.

ex:-

jshell> 5.0 / 2
$16 ==> 2.5

• Precedence in Java refers to the rules that determine the order in which operators are evaluated in an expression. It ensures that the operations in an expression are performed in the correct sequence.

ex:-

jshell> 5 5 * 6
$17 ==> 35

PRECEDENCE * / % > -

So, these three operators typically have greater precedence compared to plus and minus.
If you have any operations with these operators, first these(* / %) operators get executed.

Ex:-

jshell> 5 - 2 * 2
$18 ==> 1

jshell> 5 - 2 / 2
$19 ==> 4