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The difference between java equals and ==

The difference between equals and == in Java: == acts on variables of basic data types, and directly compares whether their stored "values" are equal; the equals method cannot act on variables of basic data types.

Nov 15, 2019 am 09:22 AM

java

Java determines whether it is a palindrome

The first is to invert the strings and compare them one by one. The second method is to invert the string and create a new string for direct comparison. The third method is to compare by intercepting strings. The fourth method is to use the boolean method to directly determine whether it is a palindrome number.

Nov 15, 2019 am 09:19 AM

java judgment palindrome

How many bytes are int in java?

The int data type in Java is a 4-byte, 32-bit, signed integer represented in two's complement. Its value range is: [-2 to the 31st power (-2147483648), 2 to the 31st power minus one (2147483647)]. It is stored in the memory in the form of complement.

Nov 15, 2019 am 09:11 AM

java

How to define array in java

Dynamic mode (specify the length of the array), format: "Data type stored in array [] array name = new Data type stored in array [length];". Static mode (specify the elements of the array), format: "data type [] array name = new data type [] {element 1, element 2, element 3...};".

Nov 14, 2019 pm 05:59 PM

java definition array

What are the differences between java abstract classes and interfaces?

The difference between interfaces and abstract classes: Abstract classes can contain ordinary methods, but interfaces can only contain public abstract methods. Member variables in abstract classes have no access restrictions, but variables in interfaces can only be modified by public static final, etc.

Nov 14, 2019 pm 05:47 PM

java the difference abstract class interface

java what is encapsulation

Encapsulation: Hiding some information of a class inside the class and not allowing direct access by external programs. Instead, the hidden information is operated and accessed through the methods provided by the class. Benefits: Data can only be accessed through specified methods; the instance details of the class are hidden to facilitate modification and implementation.

Nov 14, 2019 pm 05:38 PM

java encapsulation

java what is entity

Java entities are specific classes, like the M in MVC refers to entities, which are divided into business logic layer, DAO layer, and controller layer. The DAO layer and business logic layer operate on entity objects. Generally, a single piece of data taken out from the database is packaged into an entity class for easy operation, or a specific class in a Java program is packaged into an entity.

Nov 14, 2019 pm 05:33 PM

java entity

java what is serialization

Serialization is a mechanism used to process object streams. The so-called object stream is to stream the contents of objects. The streamed objects can be read and written, and the streamed objects can also be transmitted between networks. Serialization is to solve the problems caused when reading and writing object streams.

Nov 14, 2019 pm 05:26 PM

java Serialization

java what is instantiation

The process of creating an object is called instantiation, so sometimes we also call an object an instance of a class. For example: "Demo demo = new Demo();".

Nov 14, 2019 pm 05:19 PM

java Instantiate

java what is distributed

Distribution means distributing back-end work to multiple hosts through a computer network, and multiple hosts work together to complete the work. Technologies used in distributed applications: network communication, message-based inter-system communication and remote-call-based inter-system communication.

Nov 14, 2019 pm 05:10 PM

java distributed

How to package java

First, right-click the project and select "Export", then select "JAR file". Then select the necessary files in the project and select the path to save the jar file package. Then click "Next", then "Next", and finally select "Finsh".

Nov 14, 2019 pm 05:00 PM

java Pack

How to initialize an array in java

Array initialization is the process of making the array name point to the array object. This process is mainly divided into two steps. The first is to initialize the array object, that is, allocate memory space and assign values ??to the elements in the array. The second is to initialize the array name, that is Assign the array name to a reference to the array object. There are two ways to initialize an array, namely static initialization and dynamic initialization.

Nov 14, 2019 pm 04:40 PM

java initialization array

How to call java interface

First open Eclipse to create the project and package. Then create an interface and define interface methods. Then create the interface implementation class, name the class, implement the interface in the class, and override the interface methods. Create another class and define a constructor with parameters, using the interface type to define the parameters. Finally, define the method of the class, that is, use the interface variable to call the interface method.

Nov 14, 2019 pm 04:26 PM

java interface transfer

What is java polymorphism

Polymorphism is the ability of the same behavior to have multiple different manifestations or shapes. Polymorphism is the same interface, using different instances to perform different operations. Polymorphism is the manifestation of multiple manifestations of an object.

Nov 14, 2019 pm 04:20 PM

java Polymorphism