Java Tutorial: Part 1. Getting Started

Java Tutorial
Part 1: Getting Started
with Java Coding

Welcome
to Coding
Writing
and Running
Java Code

 Coding means to give commands to tell the computer what to do
 Sample command:
 A computer program is a sequence of commands (lines of code)
What is Coding?
System.out.println("Hey, I am coding");
System.out.println("First command");
System.out.println("Second command");
System.out.println("Third command");

Repl.it: An Online Coding Environment
Register at:
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Write, compile
and run code in
Java, JS, Python
and others

Repl.it: An Online Coding Environment

 Calculate an expression and print its value:
Commands in Java – Examples
System.out.println(5 + 5);
 Check if certain word contains another word
System.out.println("softuni".contains("uni"));
 Print the numbers from 1 to 100
for (int i = 1; i <= 100; i++)
System.out.println(i);

Coding
Concepts
Programming,
Commands, Code,
Algorithms, IDEs

 Programming means writing computer programs (commands)
 Using certain programming language, such as Java or Python
 Algorithm == a sequence of commands that achieves certain result
 Programming (coding) is performed by programmers (developers)
 Programmers use IDE (like IntelliJ IDEA or Eclipse or REPL.it) to:
 Write the code
 Run and test the code
 Find a fix bugs (debug the code)
Programming and Algorithms

 Sample Java program (sequence of Java commands):
Computer Program – Example
int size = 5;
System.out.println("Size = " + size);
System.out.println("Area = " + size * size);

 Sample complete Java program (class + method + commands):
Complete Computer Program
public class Main {
public static void main(String[] args) {
int size = 5;
System.out.println("Size = " + size);
System.out.println(
"Area = " + size * size);
}
}

 Java program, which converts from USD to EUR (at fixed rate)
Console-Based Java Program – Example
Scanner scanner = new Scanner(System.in);
int dollars = scanner.nextInt();
double euro = dollars * 0.883795087;
System.out.println("Euro: " + euro);
Put this line of code:
import java.util.Scanner;
before the class definition

The Judge System
Sending your Solutions
for Automated Evaluation

Testing the Program in the Judge System
 Test your code online in the SoftUni Judge system:
https://judge.softuni.org/Contests/3250

 To learn coding, you need to write code!
 Watching videos gives you only knowledge
 Solving the exercises, gives you experience and
practical skills
Learn by Doing
Write and submit the
coding exercises!

 Write a Java program, which:
 Prints "Hello Java" on the console
 Submit your solution in the SoftUni judge:
https://judge.softuni.org/Contests/Practice/Index/3250
Problem: Print "Hello Java"

Solution: Print "Hello Java"
public class Main {
System.out.println("Hello Java");
}
}

Submission in the Judge System

 Write a Java program, which:
 Calculates the value of 5 * 5
 Prints the result at the console
 Submit your solution in the SoftUni judge:
Problem: Calculate and Print 5 * 5

Solution: Calculate and Print 5 * 5
public class Main {
System.out.println(5 * 5);
}
}

 Write a program to print your name at the first line and
calculate and print the expression 5 + 3 at the second line
 The expected output from your program might look like this:
 Another example of valid output:
Problem: Name and Expression
Maria
8
Peter
8

 Write a program, which calculates and prints the value of the
following expressions:
 5 + 3 * 2
 4 * (2 + 3)
 (2 + 5) * (8 - 2) / 7
Problem: Calculations

 Write a program, which:
 Prints a square of 7 * 7 stars like this:
Problem: Square of 7 * 7 Stars
* * * * * * *
* * * * * * *
* * * * * * *
* * * * * * *
* * * * * * *
* * * * * * *
* * * * * * *

 First solution:
 Second solution:
Solution: Square of 7 * 7 Stars
System.out.println("* * * * * * *");
for (int i = 0; i < 7; i++)

Problem: EUR to USD Converter
 Write a Java program, which converts from USD to EUR
 Assume the EUR/USD rate is fixed: 1.17 USD for 1 EUR
 Sample input:
 Sample output:
5
USD = 5.85

Solution: EUR to USD Converter
import java.util.Scanner;
public class Main {
Scanner scan = new Scanner(System.in);
double eur = scan.nextDouble();
double usd = eur * 1.17;
System.out.println("USD = " + usd);
}
}

 The only way you can learn coding is by practice
 By writing code, a lot of code, every day
Learn by Doing
Write and submit the coding
exercises to gain experience!

 …
 …
 …
Next Steps
 Join the SoftUni "Learn To Code" Community
 Get Help from the Mentors
 Meet the Other Learners
 Get Free Coding Lessons
https://softuni.org

Java Tutorial: Part 1. Getting Started

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