The data types in Java are divided into two categories: basic types and reference types. Basic types include int, float, double, char, boolean and other eight types. Reference types include classes, arrays and interfaces. type.
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java data types include:
1. Basic data types
Simple data types are built-in data that cannot be simplified Types, defined by the programming language itself, represent real numbers, characters, and integers.
There are eight basic data types in Java, which are the following types:
| Data type | Description | Occupied bytes | Value range | Default value |
| int | Integer type, used to store integers | 4 bytes | -2147483648~2147483647 | 0 |
| byte | The smallest data type in Java | 1 byte | -128~127 | 0 |
| short | Short integer | 2 bytes | -32768~32717 | 0 |
| long | Long integer | 8 bytes | -2^63~2^63-1 | 0L |
| float | Floating point type, used to store numbers with decimal points | 4 bytes | / | 0.0f |
| double | Double precision floating point type, used to store numbers with decimal points | 8 Bytes | / | 0.0d |
| char | character type, used to store a single character | 2 bytes | 0~65535 | empty |
| boolean | Boolean type, used to determine true or false | 1 byte | There are only two values, namely true and false | false |
Note: One byte is equal to 8 bits (bit)
2 , Reference data type:
In Java, reference type variables are very similar to C/C pointers. A reference type points to an object, and a variable pointing to an object is a reference variable. These variables are assigned a specific type when declared, such as Employee, Puppy, etc. Once a variable is declared, its type cannot be changed.
There are three reference types in Java, namely classes, arrays, and interfaces. The default values of these reference types are null
Basic The difference between types and reference types:
The difference between basic data types and reference types is mainly that basic data types are allocated on the stack, while reference types are allocated on the heap
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