The following table shows the primitive data types in Java.
| Data Type | Size | Description |
|---|---|---|
byte |
8-bit (1 byte) | Stores numbers with a range ot -128 to 127 |
short |
16-bit (2 byte) | Integer type with a range of -32,768 to 32,767 |
int |
32-bit (4 byte) | Integer type with a range of -2,147,483,648 to 2,147,483,647 |
long |
64-bit (8 byte) | Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
float |
32-bit (4 byte) | Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits |
double |
64-bit (8 byte) | Stores fractional numbers. Sufficient for storing 15 decimal digits |
boolean |
1 bit | Stores true or false values (often can also be referred to 1 or 0) |
char |
16-bit Unicode (2 byte) | Stores a single character/letter or ASCII values |
Note that String is not a primitive data type, but a string is made up of an array of chars
Reference: Java Data Types (w3schools.com)
According to W3Schools:
"The String type is so much used and integrated in Java, that some call it "the special ninth type".
String in Java is actually a non-primitive data type, because it refers to an object. The String object has methods that are used to perform certain operations on strings. Don't worry if you don't understand the term "object" just yet. We will learn more about strings and objects later."
Some documentation will refer to numeric data types as being signed or unsigned. The word sign simply means whether the number is preceded by a "+" or "-". The range of values of an unsigned data type are simply shifted to the right.
For example: A signed short can range from -32,768 to +32,767. An unsigned short can range from 0 to 65,534.
Constants are variables that are assigned a value at declaration, and the value cannot be changed later without throwing an exception.
In C languages, such as C, C++, or C# constants are defined using the const keyword. Since const is a keyword used elsewhere in java, java using the keyword final to define static constants.
| Language | Keyword | Example |
|---|---|---|
| C | typeConstant | int decimalConstant = 42; |
| C++ | const | const int myNum = 15; |
| C# | const | const int myNum = 15; |
| Java | final | final int myNum = 15; |
| JavaScript | const | const x = 5; |
| Python | does not support constants, use naming conventions and style guides to assist developers | |
| Swift | let | let y = 4; |
| Kotlin | val | val y = 3; |