Data Types

Data Types

Data types define what information is stored

The most used of them are:

int	Whole number.
double	Floating point number.
String	Sequence of characters (text).
char	Represents a single symbol.
boolean	Can have only 2 values - true or false.

Reading And Printing Data

• Scanner scanner = new Scanner(System.in); followed by scanner.nextLine(); - reading data.
• System.out.println(); - printing data.

In order to use Scanner the following line needs to be added import java.util.Scanner;.

Variables

The variables are used to store data of certain type.

Their value can be changed any time.

Example of variables definitions:

public class Main { public static void main(String[] args) { // Declaring variable with value: int num1 = 5; // Declaring variable and setting value later: int num2; num2 = -3; // String values are set between double quotes. String name = "Alex"; // Char values are set between single quotes. char letter = 'c'; boolean boolVariable1 = true; boolean boolVariable2 = false; } }

Basic program example:

Write a program that prints "Starting the program." Afterwards it must read a word and print it back.

Solution:

// So scanner can be used. import java.util.Scanner; public class Main { public static void main(String[] args) { System.out.println("Starting the program."); // Read user's input: Scanner scanner = new Scanner(System.in); String read = scanner.nextLine(); // Print back the user's input: System.out.println(read); } }

Input:

blue

Output:

Starting the program. blue

Explanation:

• import java.util.Scanner; is added so Scanner can be used.
• System.out.println is used to print message to the user.