Course Content

Java Basics

1. Getting Started

Backend Development Role of Java in the Backend Java Advantages Memory Types In Java Java's Syntax Your First Program Comments

2. Basic Types and Operations

Primitive Data Types Challenge: Primitive Types Mathematical Operations on char Mathematical Operations in Java If-Else Statement Switch-Case Statement New Task Structure Challenge: Weekday Switch

3. Loops

Introduction to Loops While-Loop Do-While Loop Challenge: Building a Server Retry Mechanism For-Loop Increment and Decrement Infinite Loop Challenge: Filtering Numbers in a Loop

4. Arrays

What is Array?Using Loops with Arrays Index Out Of Bounds Two-Dimentional Array Iteration In Two-Dimensional Array For-Each Loop

5. String

What Is String? Basic Methods In String Practical Applications of String Methods Challenge: Filter Failure Messages NullPointerException StringBuilder String Pool, Method Equals() Summary

Using Loops with Arrays

How to iterate through an array using loops?

Arrays and loops are frequently used in tandem. When dealing with a large array containing 100 or even 1000 elements, manually working with and extracting each element would be impractical. Just imagine how time-consuming it would be to manually fill such an array...

To achieve such tasks, we'll employ loops. In the previous section, we observed that we initially assigned the variable i a value of 0 in the for loop, and array indexing also starts at 0.

Let's say we have a task to display all the elements of an array of type char with a length of 10. Let's examine a code fragment that accomplishes this task:

Main


              12345678910111213
            
package com.example;

public class Main {
    public static void main(String[] args) {
        // Initializing a char array
        char[] charArray = {'c', 'o', 'd', 'e', 'f', 'i', 'n', 'i', 't', 'y'};
        
        // Printing the array using a for-loop
        for (int i = 0; i < charArray.length; i++) {
            System.out.print(charArray[i]);
        }
    }
}

Let's take a closer look at how the loop iterates over an array:

Main


              1234567891011121314
            
package com.example;

public class Main {
    public static void main(String[] args) {
        // Initializing the char array
        char[] charArray = {'c', 'o', 'd', 'e', 'f', 'i', 'n', 'i', 't', 'y'};
        
        // Printing the array using a for-loop
        for (int i = 0; i < charArray.length; i++) {
            System.out.println("Now variable i = " + i + ", and value of charArray[" + i + "] = " + charArray[i] + ";");
         // The value of `i` increments with each loop iteration
        }
    }
}

Task

Swipe to start coding

We have an array with the hours worked by an employee over a number of days. You need to calculate the average number of hours per day and provide feedback based on the result.

Create a method called calculateAverage(int[] workHours) that returns a double.
Inside this method:
- Determine the length of the array and store it in a variable (e.g., sizeMassive).
- Use a for loop to iterate over each element of the array.
- Accumulate the total number of hours into a variable totalHours.
- After the loop, compute the average by dividing totalHours by the size of the array, casted to double.

Solution

solution

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Section 4. Chapter 2

Using Loops with Arrays

How to iterate through an array using loops?

Let's say we have a task to display all the elements of an array of type char with a length of 10. Let's examine a code fragment that accomplishes this task:

Main


              12345678910111213
            
package com.example;

public class Main {
    public static void main(String[] args) {
        // Initializing a char array
        char[] charArray = {'c', 'o', 'd', 'e', 'f', 'i', 'n', 'i', 't', 'y'};
        
        // Printing the array using a for-loop
        for (int i = 0; i < charArray.length; i++) {
            System.out.print(charArray[i]);
        }
    }
}

Let's take a closer look at how the loop iterates over an array:

Main


              1234567891011121314
            
package com.example;

public class Main {
    public static void main(String[] args) {
        // Initializing the char array
        char[] charArray = {'c', 'o', 'd', 'e', 'f', 'i', 'n', 'i', 't', 'y'};
        
        // Printing the array using a for-loop
        for (int i = 0; i < charArray.length; i++) {
            System.out.println("Now variable i = " + i + ", and value of charArray[" + i + "] = " + charArray[i] + ";");
         // The value of `i` increments with each loop iteration
        }
    }
}

Task

Swipe to start coding

We have an array with the hours worked by an employee over a number of days. You need to calculate the average number of hours per day and provide feedback based on the result.

Create a method called calculateAverage(int[] workHours) that returns a double.
Inside this method:
- Determine the length of the array and store it in a variable (e.g., sizeMassive).
- Use a for loop to iterate over each element of the array.
- Accumulate the total number of hours into a variable totalHours.
- After the loop, compute the average by dividing totalHours by the size of the array, casted to double.

Solution

solution

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 4. Chapter 2

Switch to desktop for real-world practiceContinue from where you are using one of the options below