Learning Java - Part 3 - Building Strong Foundations – Data Types & Variables смотреть онлайн

We are ready to write our first Java program. Just like we write essays using some kind of word editor, we need a text editor to write our code. 

In computer science, data is information that is stored or processed by a computer. While that might seem fairly abstract, there are many data points we use in everyday life. Your name, your age, the number of oranges in your pantry, whether your hall light is on or off. These can all be considered pieces of data, and we represent pieces of data in code using data types. 

Similar to other programming languages, Java classifies different pieces of data with data types based on their value. For example, there's a data type for letters and symbols, and there are various data types for numbers. Ultimately, a data type provides a set of possible values, and if a piece of data is one of these values, it is classified as that specific type. 

Java separates its data types into two main categories that are then broken down further into more distinct data types. One of the categories is called primitive data types which consist of the most basic data types in the Java language. The most important primitive data types include Boolean, int, double, and char. There are other primitive types that exist in Java, but these are the most foundational. 

The second category is called reference types, and we'll talk about reference types in a later lesson. 

Diving deeper into these primitive types, the Boolean data type represents a true or false value. This means the data piece of whether the hall light is on or off could be represented as a Boolean in code. It might have the value true, or it might have the value false, but it can never be both. It must be either true or false. 

The last primitive type we'll talk about is a char which is short for character. A char represents a single letter or symbol. Some possible values for a char could be your first initial or last initial, your favourite letter, or the hashtag symbol. 

We classify these data types, Boolean, int, double, char, as primitive types because they are the basis in foundation for all other data types within the Java programming language. Let's try using our primitive types in Java.