Et foredragsuddrag med en mentor som en del af Codegym University-kurset. Tilmeld dig hele kurset.


"Hej, Amigo. I dag vil vi tale om if/else-udsagn ."

"Programmer ville være til lidt nytte, hvis de ikke reagerede på skiftende ydre omstændigheder. Et program skal vide, hvordan det tilpasser sig omstændighederne og udfører én handling i ét tilfælde og andre handlinger i andre tilfælde. I Java opnås dette ved hjælp af 'if/else statement' – en speciel konstruktion, der gør det muligt at udføre forskellige kodeblokke, hvis en betingelse er opfyldt."

"Den består af tre dele: ' betingelse ', ' kommando 1 ' og ' kommando 2 '. Hvis betingelsen er sand, så udføres ' kommando 1 ', ellers udføres 'kommando 2' . Disse kommandoer udføres aldrig begge. Udsagnet ser nogenlunde sådan ud:"

Kode for en if/else-erklæring
if (condition)
    command_1;
else
    command_2;

"Hvor spændende! Jeg tror, ​​at den udtalelse vil gøre programmering meget mere interessant!"

"Jep. Her er et par eksempler til dig:"

Kode Forklaring
1
if (a < b)
    System.out.println("A is less than B");
else
    System.out.println("B is less than  A");
Hvis a er mindre end b, vil den første kommando blive udført. Ellers vil den anden kommando blive udført . Kommandoerne udføres aldrig begge.
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");
}
Du kan erstatte en kommando med en kodeblok. Resten er det samme.
3
if (a < b)
{
    a = 0;
}
else
{
}
Du kan udelade den anden blok, hvis den er tom.
Disse tre eksempler er fuldstændig ækvivalente.
Du kan udelade de krøllede parenteser, hvis du kun skal udføre én kommando. Hvis du har mere end én kommando, skal du beholde parenteserne.
4
if (a < b)
{
    a = 0;
}
5
if (a < b)
    a = 0;

"Diego bad mig lige give dig et par opgaver."

2
Opgave
Java Syntax,  niveaulektie
Låst
Good or bad?
Student robot Peter is an overachiever. Previously, his server was configured to receive scores on a five-point scale, but now his teachers have switched to a 12-point scale. But Peter doesn't know this. He's still focused on getting fives. Let's write him a compare method that compares any number with five.
4
Opgave
Java Syntax,  niveaulektie
Låst
Closest to 10
Ten is extremely popular and attractive number. Everyone wants to be a ten. Or at least as close to it as possible. Two numbers are standing around wondering which of them is cooler. Answer: whichever is closer to ten. Let's write these numbers a displayClosestToTen method that will determine which of them is cooler.
4
Opgave
Java Syntax,  niveaulektie
Låst
Come on, lucky seven!
Dice games are popular on the planet Foggy Multidimensions. The rules are different than the Earth version: Multidimensionals perceive far more dimensions than primitive three-dimensional earthlings. Their die has 4294967295 faces. Players win only if they roll a number between 50 and 100. We'll write a method that checks whether the die roll is in this range.
4
Opgave
Java Syntax,  niveaulektie
Låst
Seasons on Terra
An Earth year consists of four seasons, each of which lasts 3 months. While our ship was parked on this cradle of humanity, the Interplanetary Tax Service asked us to write a program to determine the season based on a number corresponding to the month of the year. We don't know why they want it. They say that it's none of our business. But they promised not to remain in our debt.
4
Opgave
Java Syntax,  niveaulektie
Låst
Positive and negative numbers
Diego is tall, but Alfredo is short. Rishi is experienced, but you're a "noob" programmer. Comparisons are unavoidable in life. And the same thing is true in programs. So we'll continue practicing comparisons and displaying stuff on the screen. This time let's compare the entered number with zero and manipulate it based on the result of the comparison.
4
Opgave
Java Syntax,  niveaulektie
Låst
Day of the week
Planet Terra still has "offices"—an outdated type of workspace. With current technology, there is no need for them, but earthlings tend to be nostalgic and haven't been in a hurry to eradicate them. Terrestrial office workers develop "TGIF syndrome": they constantly want to know what day of the week it is. Let's write a program for them!

Et foredragsuddrag med en mentor som en del af Codegym University-kurset. Tilmeld dig hele kurset.