Course New Java Syntax - Lecture: Conditional operators

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:"


if (a < b)
    System.out.println("A is less than B");
else
    System.out.println("B is less than  A");
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");
}
if (a < b)
{
    a = 0;
}
else
{
}
if (a < b)
{
    a = 0;
}
if (a < b)
    a = 0;

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

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

public class Solution { public static void main(String[] args) throws Exception { //write your code here BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String sNumber = reader.readLine(); int side1 = Integer.parseInt(sNumber); sNumber = reader.readLine(); int side2 = Integer.parseInt(sNumber); sNumber = reader.readLine(); int side3 = Integer.parseInt(sNumber); if ((side1>(side2+side3)) || (side2>(side1+side3)) || (side3>(side1+side2))) { System.out.println("The triangle is not possible."); }else{ System.out.println("The triangle is possible."); } } }

Comments (137)

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qaz_gangnam Level 8, 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

5 February 2023

In these tasks we practice if-then-else, Logical Operators, keyboard input, operations, etc. We got this! 😘

Robbie_Robot Level 4, California, United States

4 October 2022

@johnsquirrels, So in the first lecture I see the slide the speaker is referencing is titled, someusers/directory/codegym/Conditionalstatement_US_.pdf Where do we access these .pdf learning materials??

Omar Pérez Pacheco Level 6, Mexico

2 September 2022

Hice el código de la siguiente manera y si me arroja los resultados que solicita. Intenté con Netbeans para probarlo y poner distintos números y si me sale como piden la solución. Me podrías ayudar en que estoy mal, porfa

calibers16 Level 6, Knowhere, United States

13 August 2022

Now we're getting to the fun stuff! Love me some else-if statements!

Ryan D Vibbert Level 26, United States of America, UK

22 February 2022

displays "The number is less than 5" if the method argument is less than 5, otherwise, displays "The number is greater than 5". Requirements are not called out correctly as you must input it is equal to 5 or that it is equal or greater than 5

Steve C. Ands Level 10, Medellín, Colombia

27 November 2021

Que estupidez. Lo primero que se me ocurrió fue resolverlo con un condicional múltiples exactamente como está en la tarea descargada porque ya había hecho esto con condicionales múltiples, pero otro lado de mi mente dijo hazlo con condicionales simples (if, else) porque es lo que estamos viendo. Y como no lo consigo descargo la solución para estudiarla y resulta ser un condicional múltiples cuando en el curso ni se ha tocado. Y no entiendo lo de las estaciones. La meteorología no es mía.

Elans Level 4, Birmingham, United Kingdom

4 September 2021

How come Eclipse IDE shows result: 4 4 , when here same code shows 6 6 ? 🤔

Dave Level 6, Saskatoon, Canada

5 July 2021

Rule of the triangle works with an AND condition for each side being less than the sum of the other two, but it fails if you try to use an OR condition for the converse. Am I missing something or is the testing flawed here? This Passes the test: public class Solution { public static void main(String[] args) throws Exception { //write your code here BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String sNumber = reader.readLine(); int side1 = Integer.parseInt(sNumber); sNumber = reader.readLine(); int side2 = Integer.parseInt(sNumber); sNumber = reader.readLine(); int side3 = Integer.parseInt(sNumber); if ((side1<(side2+side3)) && (side2<(side1+side3)) && (side3<(side1+side2))) { System.out.println("The triangle is possible."); }else{ System.out.println("The triangle is not possible."); } } } But this fails:

Justin Smith Level 40, Greenfield, USA, United States

4 July 2021

When I run the program for "Come On, Lucky Seven" after entering my code, this is the result: The number a is in the interval. The number a is not in the interval. The number a is not in the interval. I believe this is exactly the result it's supposed to get. However when I run validation, it gives everything green checkmarks except for the last part that says "The checkInterval method should display text on the screen in accordance with the task conditions."

	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;`