Variables and Data Types in Java

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In Java, a strongly-typed and statically-typed language, the data we use in code has well-defined types. This means you must declare the data type when creating a variable.
For example:

int answerToEverything = 42;
System.out.println(answerToEverything);

Here, the variable answerToEverything is of type int, meaning it can only store integer values.

Primitive and Non-Primitive Types

Java data types are categorized into primitive and non-primitive types. Primitive types include int, byte, and boolean, while non-primitive types are used to represent objects and more complex structures, such as classes and arrays.
An important distinction is that primitive types store values directly, while non-primitive types store references to the data.

Details of Primitive Types

Primitive types are essential for storing simple data and performing fast operations. Each has a specific size and range:

They are ideal for numerical calculations and manipulations. A practical example of using byte is:

byte age = 25;
System.out.println(age);

Usage Tips

Use consistent types in operations (e.g., avoid mixing int with short).
For numbers larger than int, use long with the suffix L at the end:

long population = 7_900_000_000L;
System.out.println(population);

Java allows underscores (_) to improve the readability of large numbers, as shown above. This feature was introduced in Java 7 and does not affect the actual value of the number.