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

Do-While Loop

What is the difference between while and do-while?

The do-while loop is another type of loop in Java that is similar to the while loop. However, it has one important difference: the condition is checked at the end of each iteration. This means the code block will always execute at least once before evaluating the condition.

Here's the basic syntax of the do-while loop:

Main


              123
            
do {
    // Code block
} while (condition);

Here are some key points to keep in mind about the do-while loop:

Execution flow: the code block is executed first, and then the condition is checked. If the condition is true, the loop continues to the next iteration. If the condition is false, the loop terminates, and the program continues with the next statement after the loop;
Guaranteed execution: since the code block is executed before the condition check, the do-while loop is useful when you want to ensure that the code block runs at least once, regardless of the initial condition;
Variable scope: variables defined within the code block of a do-while loop have a scope limited to that code block. They cannot be accessed outside the loop;
Use cases: the do-while loop is commonly used when you want to prompt the user for input at least once and then continue the loop based on a condition. It is also useful when iterating through a list of elements, ensuring that the loop runs at least once, even if it is empty.

Let's look at a simple example of usage and compare the results of a while loop and a do-while loop on a very basic example:

main


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        do {
            System.out.println("Do-while loop executed successfully");
        } while (1 < 0);
    }
}

while loop:

main


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        while (1 < 0) {
            System.out.println("While loop executed successfully");
        }
    }
}

We can see that when executing the do-while loop with a condition that is always false, we executed the body of the loop once, while the while loop simply gave us an error. This is the only and most fundamental difference between these two loops.

1. What will be the output of the code?

2. What will be the output of the code?

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 3

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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

Do-While Loop

What is the difference between while and do-while?

Here's the basic syntax of the do-while loop:

Main


              123
            
do {
    // Code block
} while (condition);

Here are some key points to keep in mind about the do-while loop:

Execution flow: the code block is executed first, and then the condition is checked. If the condition is true, the loop continues to the next iteration. If the condition is false, the loop terminates, and the program continues with the next statement after the loop;
Guaranteed execution: since the code block is executed before the condition check, the do-while loop is useful when you want to ensure that the code block runs at least once, regardless of the initial condition;
Variable scope: variables defined within the code block of a do-while loop have a scope limited to that code block. They cannot be accessed outside the loop;
Use cases: the do-while loop is commonly used when you want to prompt the user for input at least once and then continue the loop based on a condition. It is also useful when iterating through a list of elements, ensuring that the loop runs at least once, even if it is empty.

Let's look at a simple example of usage and compare the results of a while loop and a do-while loop on a very basic example:

main


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        do {
            System.out.println("Do-while loop executed successfully");
        } while (1 < 0);
    }
}

while loop:

main


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        while (1 < 0) {
            System.out.println("While loop executed successfully");
        }
    }
}

1. What will be the output of the code?

2. What will be the output of the code?

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 3