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Object oriented programming (basic) Object oriented and process oriented (understanding) 1. Process oriented: it emphasizes the functional behavior, taking the function as the minimum unit and considering how to do it.2. Object oriented: emphasize the objects with functions, take the class / object as the minimum unit, and consider who will d ...

abstract class summary Abstract class introduction The method in the parent class is overridden by its subclasses, and the implementation of subclasses is different. Then the method declaration and method body of the parent class only have meaning, while the method body has no meaning (because the subclass object will call its own overridden ...

8.1 string related classes Properties of String: All string literals (such as "abc") in Java programs are implemented as instances of this class Is a final class that represents an immutable character sequence and cannot be inherited String implements Java io. Serializable interface, indicating that the string can be seria ...

Chapter 1: three problems in concurrent programming 1. Visibility target Learn what visibility issues are Visibility concept Visibility: when one thread modifies a shared variable, the other needs to get the latest modified value immediately. Visibility presentation Case demonstration: one thread loops according to the flag and while of ...

aggregate Collection usage scenario Classification of sets Java collections can be divided into Collection and Map systems Collection interface: single column data, which defines the collection of methods to access a group of objects List: an ordered and repeatable collection of elementsSet: an unordered and non repeatable set of elem ...

1. Enumerations and annotations 1. Enumeration introduction Enumeration classes [pieces: one by one: examples, that is, the classes that instantiate specific objects one by one are called enumeration classes] 2. Custom class implementation enumeration You do not need to provide a setXxx method, because enumeration object values are usually ...

1. Introduction Lambda expressions are an important new feature in Java se 8Lambda expressions allow you to use expressions instead of functional interfacesLambda expressions, like methods, provide a list of normal parameters and a body that uses these parametersLambda expression can be regarded as an anonymous function based on λ ...

1. What does IO mean? What does data source mean?         Input,Output; Input and output Data source: data source 2. What is the difference between byte stream and character stream? What is the difference between an input stream and an output stream? Character stream and byte stream are a division of stream, which are di ...

1. Definitions Java enumeration is a special class, which generally represents a set of constants, such as 4 seasons of a year, 12 months of a year, 7 days of a week, Southeast, northwest and so on. Similarly, when a variable has several fixed possible values, it can be defined as an enumeration type Definition form: Modifier enum Enume ...

problem 1. If there is a very time-consuming calculation in the business: + 1 million operations (the speed is slow and the execution time becomes longer) 2. Multiple execution units in the program at the same time? And they are all cycles (dead cycles) 1, Thread 1. Background java supports multithreading (JS php) and a large number ...