user defined class

01. Object-oriented (Polymorphism concept)Definition: multiple forms of a certain type of thing. It can be understood as multiple forms of things.02. Object-oriented (polymorphism-scalability)Polymorphism: the reference of the parent class points to

1. Constants and variables2. Basic Data type3. Operatorsfirst, constant and variable1. Constantsconstant : The amount whose value is constantOnce assigned, the value can no longer be changed;That means no more re-assignment, much like a read-only

OverviewClassLoader's Parental delegation mode : ClassLoader is divided into three levels by level: Top: Bootstrap ClassLoader (root loader); Intermediate level: extension ClassLoader (Extension class loader) the lowest level app ClassLoader (app

Original addressThe loading, linking, and initialization of Java classes. The Java byte code behaves as a byte array (byte[]), while the Java class behaves in the JVM as an object of the Java.lang.Class class. A Java class can be loaded, linked, and

The role of the Java transient keyword is to implement the Serilizable interface, add the keyword transient before the serialized property, and serialize the object without serializing it to the specified destination.Transient usage Summary1) Once

Overloaded construction method, default constructor method, subclass call constructor method of parent class, scope of construction method, access level of construction methodIn most cases, the final step of initializing an object is to invoke the

1. Provide a parameterless constructor: All persisted classes should provide a parameterless constructor, which may not take the public access control. Hibernate can use Constructor.newinstance () to create an instance of a persisted class as long

One, the life cycle of a Java Virtual machine:The life cycle of a Java virtual machine A running Java Virtual machine has a clear task: Executing a java program. He runs when the program starts, and he stops at the end of the program. You run three

Hey, looking for a job is the eternal pain!!! Needless to say, recently organized a number of enterprises often asked the theoretical questions, as follows:1. What are the value types and reference types in C #?Value types: struct (numeric type,

First of all in their own mind can appear in the knowledge of a list, followed by detailed expansion.1.java environment variable, Java_home,path: $JAVA _home/bin2.java basic Data type: Byte,boolean,char short,int,long,float,double.3.String is the

Describes the 7 zones in the JVM, and then describes the scenarios in which each zone can cause a memory overflowProgram Counter: As the current thread doesbyte code line number indicator。 is a threadPrivateMemory, and the only piece does not report

Component properties:An object of a property in an entity class that belongs to a user-defined class, such as an object in an entity class that is a custom class:This address is a user-defined class.The custom class address is defined as

Basic topics status of the Java thread one. Thread state type:1. New state: A new Thread object was created.2. Ready state (Runnable): After the thread object is created, other threads call the object's start () method. The state of the

                                                                                                                                             Java third week learning experience Through this week's learning, I learned the core of Java, understood

Java Programmer face Test set (1-50)First, the Java Foundation part1. What are the aspects of object-oriented features?A: Object-oriented features are mainly in the following areas:1) Abstraction: Abstraction is the process of constructing classes

First, class loaderThe class loader (ClassLoader), as the name implies, is something that loads classes. Before we can use a class, the JVM needs to load the class's bytecode file (. class file) from disk, network, or other source into memory, and

??At the point of view of the virtual machine, there are only two different classloader:??One is to start the ClassLoader (Bootstrap ClassLoader), which is implemented in the C + + language and is part of the virtual machine itself; ??The other is

first, what is the JVM java virtual machine (English: Java Vsan, abbreviated as JVM), aka Java Virtual machine, a VM capable of running Java bytecode, A stack-structured machine to do the actual work. The first implementation,

Primarily the Springapplication.run () method, where the preparation environment and the refresh context have a more critical partThe analysis of the project is using the gs-routing-and-filtering under the Complete/gateway-0.0.1-snapshot1 Get

In Python, an assignment statement does not copy an object, but rather creates a binding between the variable and the object. For mutable collections or collections that contain mutable items, you sometimes need a copy so that you can change a copy