CodeGym /Courses /Java Syntax /Conditional operators

Conditional operators

Java Syntax
Level 4 , Lesson 4
Available

A lecture snippet with a mentor as part of the Codegym University course. Sign up for the full course.


"Hi, Amigo. Today we'll talk about if/else statements."

"Programs would be of little use if they didn't respond to changing external circumstances. A program needs to know how to adapt to circumstances and perform one action in one case and other actions in other cases. In Java, this is achieved using the 'if/else statement' – a special construct that makes it possible to perform different code blocks if a condition is satisfied."

"It consists of three parts: 'condition', 'command 1' and 'command 2'. If the condition is true, then 'command 1' is executed, otherwise 'command 2' is executed. These commands are never both executed. The statement looks more or less like this:"

Code for an if/else statement
if (condition)
    command_1;
else
    command_2;

"How exciting! I think that statement will make programming much more interesting!"

"Yep. Here are a couple of examples for you:"

Code Explanation
1
if (a < b)
    System.out.println("A is less than B");
else
    System.out.println("B is less than A");
If a is less than b, the first command will be executed. Otherwise the second command will be executed. The commands are never both executed.
2
if (a < b)
{ System.out.println("A is less than B"); System.out.println("B is greater than A"); }
else
{ System.out.println("B is less than A"); System.out.println("A is greater than B"); }
You can replace one command with a code block. The rest is the same.
3
if (a < b)
{ a = 0; }
else
{ }
You can omit the else block if it's empty.
These three examples are entirely equivalent.
You can omit the curly brackets if you only need to execute one command. If you have more than one command, you need to keep the brackets.
4
if (a < b)
{ a = 0; }
5
if (a < b)
    a = 0;

"Diego just asked me to give you a few tasks."

4
Task
New Java Syntax, level 4, lesson 4
Locked
10 numbers
10 numbers
4
Task
New Java Syntax, level 4, lesson 4
Locked
From 10 to 1
From 10 to 1
4
Task
New Java Syntax, level 4, lesson 4
Locked
You can't have too much of a good thing
You can't have too much of a good thing
4
Task
New Java Syntax, level 4, lesson 4
Locked
Seeing dollars in your future
Seeing dollars in your future

A lecture snippet with a mentor as part of the Codegym University course. Sign up for the full course.


Comments (146)
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Kelvin Level 14, Lagos, Nigeria
18 May 2025
if you get here and you find any task difficult, dont hesitate to reach out
Kelvin Level 14, Lagos, Nigeria
6 May 2025
in the closest to 10 task there is a method we are asked to use that returns the absolute value of a number, i thought the absolute value of a number is can not be negative yet we have the method returning "-a"
Phil Level 3, UK
26 December 2024
Does anyone else find the colour coding in the lesson text incredibly distracting? I can't imagine this is great for accessibility either (people who have sight issues).
nealgoogs Level 21, Eliot, United States
15 August 2024
last one, switch statement is better
rags 3 Level 5, Wichita, United States Expert
26 April 2024
On the "day of the week one I used an array[] work perfect but didnt like spelling for some reason.
Anonymous #11394127 Level 3, Ethiopia
13 September 2023
how can open the next lesson
John Squirrels Level 2, San Francisco, Poland
14 September 2023
Just click the Unlock button at the end of the lesson like you did before.
Anonymous #11263161 Level 3, Dearborn, United States
24 June 2023
Also, for
Anonymous #11263161 Level 3, Dearborn, United States
24 June 2023
On "Good or Bad," the sentence should really be "The number is equal TO or greater than 5." The grammar is not as it usually is in programming or even math. Also another minor gripe, why not just have periods end both strings?
qaz_gangnam Level 16, Korea, Republic of
6 May 2023
Omg! I'm so proud of myself! I spent almost an hour on "Crossing the road blindly", but I solved it!! and it's beautiful *u*
Lunita Level 4, Dominican Republic
5 February 2023
In these tasks we practice if-then-else, Logical Operators, keyboard input, operations, etc. We got this! 😘