Learn the basic concepts of Java such as loops, methods, and arrays.

Android Development with Java

This module will be our guide on getting started with Java. We'll start with a simple “Hello World” program and proceed to cover common concepts such as conditional statements, loops, math, and logic in Java. Then, we’ll move to more advanced concepts like inheritance, generics, and array lists, along with much more.
By the time we're done, we'll have enough knowledge to write simple Java programs.

Learn Java from Scratch

For the computer to execute the *Hello World* code you have written, it first needs to be compiled by a Java compiler. The compiler translates the computer code written in a particular programming language into the machine code.

## What does the compiler do?
In very broad terms: 

> ### 💡 **Did you Know?**
>The compiler is a translator that acts as an intermediary between the programmer and the CPU on the computer. 

A high-level language like Java is actually a sort of *'compromise'* language between the native language of the CPU (generally referred to as machine language) and the native language of the programmer (say English). 

Computers do not natively understand human languages. Therefore, the compiler is reading the code written by the programmer and translating it into machine language code that the computer can execute directly.

In `Java`, programs are **not** compiled into **executable files**; they are compiled into [$bytecode$](https://en.wikipedia.org/wiki/Java_bytecode), which the [JVM](https://www.theserverside.com/definition/Java-virtual-machine-JVM) (Java Virtual Machine) then executes at runtime. Java source code is compiled into $bytecode$ when we use the [javac](https://en.wikipedia.org/wiki/Javac)  compiler. The $bytecode$ gets saved on the disk with the file extension `.class`. When the program is to be run, the bytecode is converted using the just-in-time ([JIT](https://www.theserverside.com/definition/just-in-time-compiler-JIT)) compiler. The result is machine code, which is then fed to the memory and is executed.

In short, we follow the following two steps to execute the Java program:

1. Java programs need to be compiled to **bytecode**.

2. Then we need to convert the **bytecode** into **machine code**.

The Java classes/bytecode are compiled to machine code and loaded into memory by the JVM when needed the first time. This is different from other languages like C/C++, where programs are to be compiled to machine code and linked to create an executable file before it can be executed.






For the computer to execute the *Hello World* code you have written, it first needs to be compiled by a Java compiler. The compiler translates the computer code written in a particular programming language into the machine code.

# What does the compiler do?
In very broad terms: 

> ### 💡 **Did you Know?**
>The compiler is a translator that acts as an intermediary between the programmer and the CPU on the computer. 

A high-level language like Java is actually a sort of *'compromise'* language between the native language of the CPU (generally referred to as machine language) and the native language of the programmer (say English). 

Computers do not natively understand human languages. Therefore, the compiler is reading the code written by the programmer and translating it into machine language code that the computer can execute directly.

In `Java`, programs are **not** compiled into **executable files**; they are compiled into [$bytecode$](https://en.wikipedia.org/wiki/Java_bytecode), which the [JVM](https://www.theserverside.com/definition/Java-virtual-machine-JVM) (Java Virtual Machine) then executes at runtime. Java source code is compiled into $bytecode$ when we use the [javac](https://en.wikipedia.org/wiki/Javac)  compiler. The $bytecode$ gets saved on the disk with the file extension `.class`. When the program is to be run, the bytecode is converted using the just-in-time ([JIT](https://www.theserverside.com/definition/just-in-time-compiler-JIT)) compiler. The result is machine code, which is then fed to the memory and is executed.

In short, we follow the following two steps to execute the Java program:

1. Java programs need to be compiled to **bytecode**.

2. Then we need to convert the **bytecode** into **machine code**.

The Java classes/bytecode are compiled to machine code and loaded into memory by the JVM when needed the first time. This is different from other languages like C/C++, where programs are to be compiled to machine code and linked to create an executable file before it can be executed.






In this lesson, an explanation of how to compile your code in Java, which compilers to use and the most suitable ones for different Operating Systems, is provided.

Getting Started with Java!

Variables & User Input

Simple Maths & Logic

Strings and String Processing

Conditional Statements

Loops

Methods

Arrays

ArrayLists

Java Exam

Conclusion

Compiling Your First Java Program!

What does the compiler do?

💡 Did you Know?