1. What is an interface
The interface is a specification, similar to the interface on the hardware, the PCI slot on the computer motherboard The specification is similar to the Java interface. As long as it follows the PCI interface, any brand of card can be inserted into the PCI slot. So the interface is a specification. An interface is a description of some functions provided by something to the outside world. We can also use interfaces to implement polymorphic functions. At the same time, interfaces also make up for the weakness of Java's single inheritance, that is, a class can implement multiple interfaces.
2. What is java interface
Interface (English: Interface) is an abstract type in the JAVA programming language and is a collection of abstract methods. The interface usually starts with interface to declare. A class inherits the abstract methods of the interface by inheriting the interface. (Recommended tutorial: java tutorial)
We use the interface keyword to define the interface , generally use interfaces to declare methods or constants. Methods in interfaces can only be declarations, not specific implementations. This is different from abstract classes. Interfaces are higher level abstractions. The definition format of the interface is
public interface 接口名稱{
//可以定義常量
//方法只有方法聲明,而且是公共的。
public void 方法名稱();
...
}If a class wants to implement the interface, it only needs to use the implements keyword. The implementation class must implement all the methods in the interface
public class 實(shí)現(xiàn)類(lèi)名 implements 接口{
//實(shí)現(xiàn)接口的方法
}3. Application of interfaces
It is very simple to define an interface. Of course, it is not very simple to design a good interface. You must think about the constants and methods of this interface. But the technology is very simple. The sample code is as follows:
// 定義方法的接口
public interface Myinterface {
// 定義程序使用的常量的接口，接口中只能有常量。
public static final double price = 1450.00;
public static final int counter = 5;
//接口中所有的方法都沒(méi)有方法體。
public void add(int x, int y);
public void volume(int x,int y, int z);
}It is not difficult to implement the interface. The code is as follows:
//實(shí)現(xiàn) 接口
public class MyImple implements Myinterface {
@Override
public void add(int x, int y) {
}
@Override
public void volume(int x, int y, int z) {
}
}A class can implement multiple interfaces because Java is single inheritance. The interface can make up for this. We can define another interface
public interface MyInterface2 {
public void countpp();
}Modify the above implementation class. To implement multiple interfaces, you can use commas to separate them. Of course, all interface methods must be implemented.
//實(shí)現(xiàn) 接口1,接口2
public class MyImple implements Myinterface ,MyInterface2{
@Override
public void add(int x, int y) {
}
@Override
public void volume(int x, int y, int z) {
}
@Override
public void countpp() {
}
}The above is the detailed content of what is java interface. 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)
VSCode settings.json location
Aug 01, 2025 am 06:12 AM
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
How to handle transactions in Java with JDBC?
Aug 02, 2025 pm 12:29 PM
To correctly handle JDBC transactions, you must first turn off the automatic commit mode, then perform multiple operations, and finally commit or rollback according to the results; 1. Call conn.setAutoCommit(false) to start the transaction; 2. Execute multiple SQL operations, such as INSERT and UPDATE; 3. Call conn.commit() if all operations are successful, and call conn.rollback() if an exception occurs to ensure data consistency; at the same time, try-with-resources should be used to manage resources, properly handle exceptions and close connections to avoid connection leakage; in addition, it is recommended to use connection pools and set save points to achieve partial rollback, and keep transactions as short as possible to improve performance.
python itertools combinations example
Jul 31, 2025 am 09:53 AM
itertools.combinations is used to generate all non-repetitive combinations (order irrelevant) that selects a specified number of elements from the iterable object. Its usage includes: 1. Select 2 element combinations from the list, such as ('A','B'), ('A','C'), etc., to avoid repeated order; 2. Take 3 character combinations of strings, such as "abc" and "abd", which are suitable for subsequence generation; 3. Find the combinations where the sum of two numbers is equal to the target value, such as 1 5=6, simplify the double loop logic; the difference between combinations and arrangement lies in whether the order is important, combinations regard AB and BA as the same, while permutations are regarded as different;
Mastering Dependency Injection in Java with Spring and Guice
Aug 01, 2025 am 05:53 AM
DependencyInjection(DI)isadesignpatternwhereobjectsreceivedependenciesexternally,promotingloosecouplingandeasiertestingthroughconstructor,setter,orfieldinjection.2.SpringFrameworkusesannotationslike@Component,@Service,and@AutowiredwithJava-basedconfi
python pytest fixture example
Jul 31, 2025 am 09:35 AM
fixture is a function used to provide preset environment or data for tests. 1. Use the @pytest.fixture decorator to define fixture; 2. Inject fixture in parameter form in the test function; 3. Execute setup before yield, and then teardown; 4. Control scope through scope parameters, such as function, module, etc.; 5. Place the shared fixture in conftest.py to achieve cross-file sharing, thereby improving the maintainability and reusability of tests.
Troubleshooting Common Java `OutOfMemoryError` Scenarios
Jul 31, 2025 am 09:07 AM
java.lang.OutOfMemoryError: Javaheapspace indicates insufficient heap memory, and needs to check the processing of large objects, memory leaks and heap settings, and locate and optimize the code through the heap dump analysis tool; 2. Metaspace errors are common in dynamic class generation or hot deployment due to excessive class metadata, and MaxMetaspaceSize should be restricted and class loading should be optimized; 3. Unabletocreatenewnativethread due to exhausting system thread resources, it is necessary to check the number of threads, use thread pools, and adjust the stack size; 4. GCoverheadlimitexceeded means that GC is frequent but has less recycling, and GC logs should be analyzed and optimized.
How to work with Calendar in Java?
Aug 02, 2025 am 02:38 AM
Use classes in the java.time package to replace the old Date and Calendar classes; 2. Get the current date and time through LocalDate, LocalDateTime and LocalTime; 3. Create a specific date and time using the of() method; 4. Use the plus/minus method to immutably increase and decrease the time; 5. Use ZonedDateTime and ZoneId to process the time zone; 6. Format and parse date strings through DateTimeFormatter; 7. Use Instant to be compatible with the old date types when necessary; date processing in modern Java should give priority to using java.timeAPI, which provides clear, immutable and linear
Understanding the Java Virtual Machine (JVM) Internals
Aug 01, 2025 am 06:31 AM
TheJVMenablesJava’s"writeonce,runanywhere"capabilitybyexecutingbytecodethroughfourmaincomponents:1.TheClassLoaderSubsystemloads,links,andinitializes.classfilesusingbootstrap,extension,andapplicationclassloaders,ensuringsecureandlazyclassloa
