Kurssisisältö

Java Basics (unit tests)

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

For-Each Loop

You might wonder why we cover this loop in the section about arrays. That's because this loop is specifically designed for use with arrays or collections. You'll delve deeper into collections in a separate course.

What is a for-each loop?

The for-each loop, also referred to as the enhanced for loop, offers a concise and simplified method for iterating over elements of an array or any iterable collection in Java. It removes the necessity for explicit indexing and streamlines the code.

The syntax for this loop is as follows:

Main


              123
            
for (ElementType variable : iterable) {
    // Code to be executed for each element
}

Explanation of each element:

ElementType: the data type of elements in the array;
variable: a variable representing each array element in each iteration;
iterable: the array or iterable collection you want to iterate over.

The for-each loop automatically iterates over each element of the array or iterable collection, assigning it to the variable in each iteration until all elements have been processed.

Let's take a look at an example of using a for-each loop:

Main


              1234567891011
            
package com.example;

public class Main {
    public static void main(String[] args) {
        int[] array = {1, 2, 3, 4, 5};

        for (int element : array) {
            System.out.println(element);
        }
    }
}

We can also perform operations on each element of an array using a for-each loop. Let's consider an example task:

You need to multiply each element of a double array by 3 and display the result on the screen using a for-each loop.

Main


              123456789101112
            
package com.example;

public class Main {
    public static void main(String[] args) {
        double[] array = {1.5, 2.0, 3.4, 4.5, 5.0};

        for (double element : array) {
            element = element * 3;
            System.out.println(element);
        }
    }
}

As you can see, we are multiplying each element by 3 without using indexing, using the statement element = element * 3;.

Tehtävä

Swipe to start coding

Imagine you work in a warehouse, and you're given an array containing the weights of packages.
Your task is to write a program that checks if there are any packages with negative weights.

Use a for-each loop to iterate through all the package weights.
Inside the loop, check if the current weight is negative (< 0).
If a negative weight is found, exit the loop and return false.
If all values are non-negative, return true.

Ratkaisu

solution

Vaihda työpöytään todellista harjoitusta vartenJatka siitä, missä olet käyttämällä jotakin alla olevista vaihtoehdoista

Oliko kaikki selvää?

Kiitos palautteestasi!

Osio 4. Luku 6

For-Each Loop

What is a for-each loop?

The syntax for this loop is as follows:

Main


              123
            
for (ElementType variable : iterable) {
    // Code to be executed for each element
}

Explanation of each element:

ElementType: the data type of elements in the array;
variable: a variable representing each array element in each iteration;
iterable: the array or iterable collection you want to iterate over.

The for-each loop automatically iterates over each element of the array or iterable collection, assigning it to the variable in each iteration until all elements have been processed.

Let's take a look at an example of using a for-each loop:

Main


              1234567891011
            
package com.example;

public class Main {
    public static void main(String[] args) {
        int[] array = {1, 2, 3, 4, 5};

        for (int element : array) {
            System.out.println(element);
        }
    }
}

We can also perform operations on each element of an array using a for-each loop. Let's consider an example task:

You need to multiply each element of a double array by 3 and display the result on the screen using a for-each loop.

Main


              123456789101112
            
package com.example;

public class Main {
    public static void main(String[] args) {
        double[] array = {1.5, 2.0, 3.4, 4.5, 5.0};

        for (double element : array) {
            element = element * 3;
            System.out.println(element);
        }
    }
}

As you can see, we are multiplying each element by 3 without using indexing, using the statement element = element * 3;.

Tehtävä

Swipe to start coding

Imagine you work in a warehouse, and you're given an array containing the weights of packages.
Your task is to write a program that checks if there are any packages with negative weights.

Use a for-each loop to iterate through all the package weights.
Inside the loop, check if the current weight is negative (< 0).
If a negative weight is found, exit the loop and return false.
If all values are non-negative, return true.

Ratkaisu

solution

Vaihda työpöytään todellista harjoitusta vartenJatka siitä, missä olet käyttämällä jotakin alla olevista vaihtoehdoista

Oliko kaikki selvää?

Kiitos palautteestasi!

Osio 4. Luku 6

Vaihda työpöytään todellista harjoitusta vartenJatka siitä, missä olet käyttämällä jotakin alla olevista vaihtoehdoista