css dropdown menu example

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

@property decorator is used to convert methods into properties to implement the reading, setting and deletion control of properties. 1. Basic usage: define read-only attributes through @property, such as area calculated based on radius and accessed directly; 2. Advanced usage: use @name.setter and @name.deleter to implement attribute assignment verification and deletion operations; 3. Practical application: perform data verification in setters, such as BankAccount to ensure that the balance is not negative; 4. Naming specification: internal variables are prefixed, property method names are consistent with attributes, and unified access control is used to improve code security and maintainability.

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.

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

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

Converting an array into a list in Java requires selecting methods based on the data type and requirements. ① Use Arrays.asList() to quickly convert an object array (such as String[]) into a fixed-size List, but elements cannot be added or deleted; ② If you need a mutable list, you can encapsulate the result of Arrays.asList() through the ArrayList constructor; ③ For basic type arrays (such as int[]), you need to use StreamAPI conversion, such as Arrays.stream().boxed().collect(Collectors.toList()); ④ Notes include avoiding null arrays, distinguishing basic types from object types, and explicitly returning columns