Type Declaration

Part of the Fundamentals section of Coddy's Java journey — lesson 9 of 73.

Once a variable is declared with a certain type, it can only hold values of that type. For instance, an int variable can only hold integer values, and a String variable can only hold text.

For example:

int age = 25;        // Can only hold whole numbers
String str = "abc";  // Can only hold text

These would cause errors:

age = "defg";  // Error: can't put text in an int variable
str = 25;      // Error: can't put a number in a String variable

These are valid:

age = 26;      // OK: assigning a new integer
str = "Jane";  // OK: assigning a new text string

Challenge

Beginner

Declare the following variables with their corresponding types and values:

An int variable named count with the value 10.
A double variable named total with the value 150.75.
A char variable named grade with the value 'A'.
A boolean variable named isActive with the value false.
A String variable named userName with the value "Bob123".

After declaring these variables, use System.out.println() to output the values of the variables to the console in the following format:

Count: [value of count]
Total: [value of total]
Grade: [value of grade]
Active: [value of isActive]
User Name: [value of userName]

Cheat sheet

In Java, variables have specific types and can only hold values of that type:

int age = 25;        // Can only hold whole numbers
String str = "abc";  // Can only hold text

Type mismatches cause errors:

age = "defg";  // Error: can't put text in an int variable
str = 25;      // Error: can't put a number in a String variable

Valid reassignments must match the variable's type:

age = 26;      // OK: assigning a new integer
str = "Jane";  // OK: assigning a new text string

Try it yourself

public class Main {
    public static void main(String[] args) {
        // Declare variables here
        
        
        // Output the values
        System.out.println("Count: " + count);
        System.out.println("Total: " + total);
        System.out.println("Grade: " + grade);
        System.out.println("Active: " + isActive);
        System.out.println("User Name: " + userName);
        
    }
}