Gain insights into Java, a versatile and portable programming language. Delve into similarities with C++ and Python and learn essential Java-specific features with practical coding examples.

Looking to jump into a new programming language? Java is an easy-to-use, highly portable and ubiquitous language that is used for a variety of development purposes such as Android applications,  desktop applications, and website backend systems. Designed for programmers who are already familiar with coding in languages such as C++, Python, or other similar languages, this course articulates any Java-specific details that programmers need to know to get acquainted with the language and also highlights similarities and differences between Java and other languages through multiple coding examples.

The Complete Java Crash Course

Here is an example of creating and using a variable that will store an integer value:

class FortyTwo {
  public static void main(String args[]) {
    int meaningOfLife;
    meaningOfLife = 42;
    System.out.println(meaningOfLife);
  }
}

## Variable declaration

The statement `int meaningOfLife` is called a **variable declaration** and it causes Java to reserve a space in memory to hold an integer value; it names that space `meaningOfLife`. In languages like Python or Javascript, you can skip this step, but C and C++ also require variable declarations.

The structure of a variable declaration is the type of the variable (`int` in this case) followed by the name of the variable (`meaningOfLife`).

Unlike in dynamically-typed languages like Python or Javascript, the variable `meaningOfLife` must hold an `int` now and forever. Assigning a floating-point value like `3.14` to `meaningOfLife` will fail with a compiler error.
This may seem inconvenient, but has an advantage: if you stated the intent that `meaningOfLife` be an integer, and later try to store something else in that variable, there is an inconsistency between intent or action, a likely bug. It's better to catch such bugs at compile-time rather than during deployment. 

## Java variable naming convention: camel case

Variable names are often composed of many words. In Java, the first letter should be lowercase, and each new word should be uppercase. This convention is sometimes called "camel case", since the capital letters look like the humps on a camel's back: `meaningOfLife`.

In contrast, some other languages, such as Python, conventionally use separate words in variable names by underscores: `meaning_of_life`.


# Variable declaration

The statement `int meaningOfLife` is called a **variable declaration** and it causes Java to reserve a space in memory to hold an integer value; it names that space `meaningOfLife`. In languages like Python or Javascript, you can skip this step, but C and C++ also require variable declarations.

The structure of a variable declaration is the type of the variable (`int` in this case) followed by the name of the variable (`meaningOfLife`).

Unlike in dynamically-typed languages like Python or Javascript, the variable `meaningOfLife` must hold an `int` now and forever. Assigning a floating-point value like `3.14` to `meaningOfLife` will fail with a compiler error.
This may seem inconvenient, but has an advantage: if you stated the intent that `meaningOfLife` be an integer, and later try to store something else in that variable, there is an inconsistency between intent or action, a likely bug. It's better to catch such bugs at compile-time rather than during deployment. 

# Java variable naming convention: camel case

Variable names are often composed of many words. In Java, the first letter should be lowercase, and each new word should be uppercase. This convention is sometimes called "camel case", since the capital letters look like the humps on a camel's back: `meaningOfLife`.

In contrast, some other languages, such as Python, conventionally use separate words in variable names by underscores: `meaning_of_life`.


Java is a statically-typed language, which means that you must explicitly create each variable and tell what type of data (for example, an integer) that variable will store before using it.

Hello, Java!

Variables and expressions

Flow of control: loops and conditionals

Classes, objects, and methods

Challenge project: tetrominos

Variables; integer values with `int`

Variable declaration