Want to learn how to code? Master the foundations of Java, an in-demand programming language. Get hands-on with immersive exercises, interactive quizzes, and earn certifications to build in-demand skills.

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Java

Java is a high-level, object-oriented language known for its portability and reliability. Mastering Java is key for developers to build scalable, secure software efficiently.

In this course, you will start by mastering the art of problem-solving with simple Java programs, such as the Bottle Filling example. You will learn how to structure your solutions, create execution sheets, and enhance your problem-solving abilities through practical exercises and quizzes. Progressing further, you will learn decision-making and branching in Java, understanding flowcharts, conditional expressions, and their application. You will also learn about Java basics, including the first Java program, fundamentals, conditional statements, and error categories, followed by in-depth lessons on working with Java strings and arrays. 

By the end of this course, you will have a solid understanding of Java programming fundamentals and the ability to solve real-world problems using Java.

Learn to Code: Java for Absolute Beginners

# Problem solving with Java
The basic tools for understanding the flow and the results of simple programs are #key# execution sheets: An execution sheet is a manual way for observing and updating the values of the variables at each step of the execution of a program. #key# and #key# flowcharts: A flowchart is a diagram that helps understand the sequence of instructions in a program having decision. #key#. However, they become complicated when we have problems with a large number of decisions. Therefore, we provide **executable embedded code widgets** to observe the program output by executing it.

> We can run a program as many times as we want, to try out different inputs of variables. We can also edit these programs to observe the result of a change in a value or logic for our learning.

In Java, we use **`nextLine()`** for **input** (to read a value from the user) and **`System.out.println()`** for **print** (to display a value on the screen as output).


# Hello World
It’s time to write our first program in Java, which will simply display the message `“Hello World!”` on the screen. 



This is the code widget that we’ll use to write our Java code. We may execute our Java program by clicking the “Run” button at the bottom of the widget:

// First Java program to display Hello World
class Test
{
    public static void main(String args[]) 
    {
        System.out.print("Hello World!");
    }
}

> **Note:** We can add non-executable text in a Java program by adding a double backslash sign (`//`) at the start of the text. This type of text is called a **comment**. We use comments to include descriptions in the program.

**Explanation**
- **Line 1:** This is a comment because it starts with `//` (a double slash). It is only for the readers of this program. It describes the purpose and/or related matters of the program.
- **Line 2–3:** These are used as a requirement by the language. It is the start of the first block of code. Every starting brace `{` has a corresponding closing brace `}`, as seen in **line 8**. We will be using these lines, as is, in almost every Java program.

- **Line 4–5:** These are the start of the executable part of the program. Every executable Java program has a main, which serves as its entry/starting point. The starting brace `{` indicates the start of the second block of code. See the corresponding closing brace `}` in **line 7**.
- **Line 6:** It is the only line that caused the program to give output. It corresponds to the purpose of the whole program. Every other line is in support of **line 6**. We use `System.out.` before `print` as a requirement by the language.
- **Line 7:** This is the end of the main block of code. It corresponds to the opening brace in **line 5**.

- **Line 8:** This is the end of the class block of code. It corresponds to the opening brace in **line 3**.


# New line in the output
There are different ways of giving a line break in the output, as demonstrated in the following code:



Learn to create and execute the first Java program.

About the Course

Problem Solving with Simple Programs

Decisions and Branching

Java Basics

Repetition with Loops

Strings and Arrays

Methods

Appendix - Complex Programs

Wrap Up

First Java Program

Problem solving with Java