There are only 8 basic data types in Java, just remember them. Except these are all reference types.
Introduction to commonly used data types in java: (Recommended: java video tutorial)
Four categories and eight basic data types in java
The first category: integer type byte short int long
The second category: floating point type float double
The third category: logical type boolean (it has only two values ????that can be true or false)
Category 4: Character type char
Data that can directly allocate memory on the stack is a basic data type.
Reference data type: The reference to the data is on the stack, but its object is on the heap.
If you want to learn Java well, you must know where various data are stored in memory. Having a good understanding of memory can help you analyze programs.
Byte:
boolean Boolean type: 1/8
byte Byte type: 1
char Character type: 2 One character can store one Chinese characters
short short integer type: 2
int integer type: 4
float floating point type (single precision): 4
long long integer type :8
double Double precision type (double precision) 8
The default integer type in Java is the int type. If you want to define it as a float type, you must add l or L after the value. ;
The default floating point type is also a double precision floating point. If you want to define it as a float type, you must add f or F after the value.??
One byte is equal to 8 bits, and one byte is equal to 256 numbers, which is -128 to 127, a total of 256.
kB means kBytes Bytes means "bytes"!
K means thousands, because the computer calculates through binary, 10 1's are exactly 1024
1111111111 (binary) = 1024 (decimal)
1Bytes (word section) = 8bit (bit)
An English letter or an Arabic numeral is one character, occupying one byte
One Chinese character is two characters, occupying two bytes.
Generally, when talking about size, Bytes is used with a capital "B". When talking about network speed, bits are used. Note that it is a lowercase "b".
Example: A file has 8MBytes
Example: The rate at which I download files is 256KB/s, which is 2Mbit. This is usually the rate at which we use broadband Internet access.
Automatic conversion of basic data types
##byte->short,char -> int -> long float -> double int -> float long -> double Remember: small can be converted to large, but accuracy will be lost if large is converted to small! ! ! For more java knowledge, please pay attention to thejava basic tutorial column.
The above is the detailed content of What are the commonly used data types in Java?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

SetupaMaven/GradleprojectwithJAX-RSdependencieslikeJersey;2.CreateaRESTresourceusingannotationssuchas@Pathand@GET;3.ConfiguretheapplicationviaApplicationsubclassorweb.xml;4.AddJacksonforJSONbindingbyincludingjersey-media-json-jackson;5.DeploytoaJakar

Maven is a standard tool for Java project management and construction. The answer lies in the fact that it uses pom.xml to standardize project structure, dependency management, construction lifecycle automation and plug-in extensions; 1. Use pom.xml to define groupId, artifactId, version and dependencies; 2. Master core commands such as mvnclean, compile, test, package, install and deploy; 3. Use dependencyManagement and exclusions to manage dependency versions and conflicts; 4. Organize large applications through multi-module project structure and are managed uniformly by the parent POM; 5.

First, use JavaScript to obtain the user system preferences and locally stored theme settings, and initialize the page theme; 1. The HTML structure contains a button to trigger topic switching; 2. CSS uses: root to define bright theme variables, .dark-mode class defines dark theme variables, and applies these variables through var(); 3. JavaScript detects prefers-color-scheme and reads localStorage to determine the initial theme; 4. Switch the dark-mode class on the html element when clicking the button, and saves the current state to localStorage; 5. All color changes are accompanied by 0.3 seconds transition animation to enhance the user

Use datetime.strptime() to convert date strings into datetime object. 1. Basic usage: parse "2023-10-05" as datetime object through "%Y-%m-%d"; 2. Supports multiple formats such as "%m/%d/%Y" to parse American dates, "%d/%m/%Y" to parse British dates, "%b%d,%Y%I:%M%p" to parse time with AM/PM; 3. Use dateutil.parser.parse() to automatically infer unknown formats; 4. Use .d

To generate hash values using Java, it can be implemented through the MessageDigest class. 1. Get an instance of the specified algorithm, such as MD5 or SHA-256; 2. Call the .update() method to pass in the data to be encrypted; 3. Call the .digest() method to obtain a hash byte array; 4. Convert the byte array into a hexadecimal string for reading; for inputs such as large files, read in chunks and call .update() multiple times; it is recommended to use SHA-256 instead of MD5 or SHA-1 to ensure security.

The settings.json file is located in the user-level or workspace-level path and is used to customize VSCode settings. 1. User-level path: Windows is C:\Users\\AppData\Roaming\Code\User\settings.json, macOS is /Users//Library/ApplicationSupport/Code/User/settings.json, Linux is /home//.config/Code/User/settings.json; 2. Workspace-level path: .vscode/settings in the project root directory

Yes, a common CSS drop-down menu can be implemented through pure HTML and CSS without JavaScript. 1. Use nested ul and li to build a menu structure; 2. Use the:hover pseudo-class to control the display and hiding of pull-down content; 3. Set position:relative for parent li, and the submenu is positioned using position:absolute; 4. The submenu defaults to display:none, which becomes display:block when hovered; 5. Multi-level pull-down can be achieved through nesting, combined with transition, and add fade-in animations, and adapted to mobile terminals with media queries. The entire solution is simple and does not require JavaScript support, which is suitable for large

Installing the Emmet plug-in can achieve intelligent automatic closing of tags and support abbreviation syntax; 2. Enable "auto_match_enabled":true to allow Sublime to automatically complete simple tags; 3. Use Alt . (Win) or Ctrl Shift . (Mac) shortcut keys to manually close the current tag - it is recommended to use Emmet in daily life. The latter two methods can be combined, which is efficient and simple to set.
