2 - Data Type Examples

Time to explore 2 - Data Type Examples 😎

📊 Examples with Numbers and Strings

In this lesson, we’ll learn about different data types in Java — these are the kinds of values your robot can use, like numbers, letters, and words. Each type has its own special rules and powers. Let’s check them out!

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🔢 Integers (int)

Integers are whole numbers. That means they don’t have decimals. You can use them to count things, measure scores, or store positions.

int score = 10;
int lives = 3;

Java automatically uses integer math when you’re working with just int numbers.

Operation	Code	What It Does	Result
Addition	int sum = 5 + 2;	5 plus 2	7
Subtraction	int diff = 5 - 2;	5 minus 2	3
Multiplication	int product = 5 * 2;	5 times 2	10
Division	int quotient = 5 / 2;	5 divided by 2, decimal gets cut off	2
Remainder	int rem = 5 % 2;	What’s left after dividing 5 by 2	1

📝 Note: If you divide 5 / 2 using int, you don’t get 2.5 — Java chops off the decimal and gives just 2.

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🧮 Decimal Numbers (double)

A double can store decimal numbers like 2.5 or 3.14. It’s great for when you need precise values, like distances or percentages.

double speed = 2.5;
double batteryLevel = 75.5;

Operation	Code	What It Does	Result
Multiplication	double r = 4.5 * 1.2;	4.5 times 1.2	5.4
Order of Ops	double r = 4.5 * 1.2 + 3;	Multiply first, then add	8.4
Division	double d = 5.0 / 2.0;	Divides with decimals	2.5

✅ Reminder: To get a decimal answer, at least one number must have a .0 in it! If both numbers are int, you’ll get an int result.

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🔤 Characters (char)

A char (short for character) stores a single letter or symbol. It’s surrounded by single quotes like 'A' or '%'.

char grade = 'A';
char symbol = '!';

Operation	Code	What It Does	Result
Assign letter	char letter = 'A';	Stores letter A	'A'
Next letter	char next = (char)(letter + 1);	Adds 1 to A (ASCII code) = B	'B'
Symbol	char symbol = '!';	Stores exclamation mark	'!'

💡 Fun Fact: Letters are secretly stored as numbers (ASCII). 'A' is 65, 'B' is 66, and so on!

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🧵 Strings

A String is a bunch of characters stuck together — like a word or sentence. You use double quotes for strings: "Hello"

String name = "Robo";
String message = "Hello, world!";

Operation	Code	What It Does	Result
Basic join	"Hello" + " World"	Joins the two parts together	”Hello World”
Add variable	"Hello, " + name	Adds the value inside name	”Hello, Robo”
Add number to string	"Score: " + 10	Turns 10 into text, then joins it	”Score: 10”
Multi-line	"Line1\nLine2"	\n makes a new line	Line1 (newline) Line2

💡 Tip: Strings aren’t just text — they’re objects that have cool powers like .length() (how long it is) and .toUpperCase() (shouty version!)

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🧠 Summary Table

Data Type	What It’s For	Examples	Notes
int	Whole numbers	5 + 2, 10 / 3, 7 % 4	No decimals, does regular math
double	Decimal numbers	5.0 / 2.0, 3.14 * 2, 1.5 + 3	Gives accurate decimal answers
char	Single characters	'A', 'Z', '!', '1'	Must use single quotes ' ', ASCII aware
String	Words and sentences	"Hello" + name, "Score: " + 5	Double quotes, use + to build messages

🚀 Practice in Visual Studio Code

Time to try these datatypes yourself! Open Visual Studio Code and create a new file called Example.java.

public class Example {
    public static void main(String[] args) {
        System.out.println("Hello Robocode!");
    }
}

Save the file, then run the following in your VS Code terminal:

javac Example.java
java Example

You’ll see the greeting printed to the console. Modify the message or add variables from the table above, recompile with javac, and run again to observe the changes.

🧪 Challenge: Try printing out these different types using System.out.println() and see what happens!

System.out.println(5 + 2);           // int math
System.out.println(5.0 / 2.0);       // double math
System.out.println('A' + 1);         // adds to char, prints number!
System.out.println("Hi " + "there!"); // String join

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➡️ 🤖 Minigame!

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