• `Differences between ‘abstract class’ and’ interface ‘in Java


    abstract class JavaAllowed inabstractThe modifier declares the method. At this time, only the method is defined but not implemented(abstractThe decorated method has no body, only a signature and a semicolonBelow isabstractMethods and theabstractClass related rules: As long as there is one in the classabstractMethod, the class itself automatically becomesabstract, and must be declared asabstract classOtherwise, […]

  • Laravel manual switch eloquest modifier


    Original link: he Xiaodong blog The test framework version is laravel 6.5, and the eloquest modifier can be used in – > view the document The scenario of the manual switch of the modifier is the differential return data. For example, in the background management, the image address needs to be relative to the path, […]

  • Practical skills of Vue Foundation


    Vue has heard of it before, and has a little knowledge of it. At that time, I was still keen to write some method encapsulation in native JavaScript, which is not why. I feel so handsome. I have more or less touched the usage of jQuery. Up to now, I have forgotten some methods of […]

  • What’s new in C × 8.0


    1. Readonly members The readonly modifier can be applied to any member of a structure, indicating that the member does not modify the state. This is finer than applying the readonly modifier to a struct declaration. public struct Point { public double X { get; set; } public double Y { get; set; } public […]

  • IOS — possible crash caused by objc, association and design


    //Objc assignment is similar to our commonly used assignment. The feature of the assignment strategy is that after the object is released, it will not actively set the application object as nil, which will lead to the risk of application crash due to accessing the zombie object. To solve this problem: we can create a […]

  • About the “?” in C #?


    Catalog 1. Nullable type modifier (T?) 2. Ternary (Operator) Expressions (?:) 3. Empty merge operator (??) 4. NULL check operator (?.) Shanzm-23 August 2019 19:59:46 1. Nullable type modifier (T?) Reference types in strongly typed languages can be null, such as:string str=null;If you define a value type as null, you will report an error. However, […]

  • The Difference and Usage of?/:/?? in C______________


    In the construction process of the project, I inadvertently saw a code about the three symbols of the title above, so I carefully recorded it for occasional needs. 1. Nullable type modifier (?) : Reference types can use null references to represent a non-existent value, whereas value types cannot usually be null.For example: string STR […]

  • C# in parameter modifier


    In modifier record: The new version of C # adds an in modifier: to ensure that the data sent to the method is not changed (value type), when the in modifier is used to refer to the type, the content of the variable can be changed, but the variable itself cannot be changed. Personal Understanding: […]

  • Mongodb modifier ($inc/$set/$unset/$push/$pop/upsert)


    In addition to replacement, only partial updates are needed for one or more documents. Atomic update modifiers can be used to update documents efficiently. Update modifier is a special key.Used to specify complex operations, such as adding, deleting, or adjusting keys, and possibly an array of operations or embedded documents. 1.$inc What does this modifier […]

  • Regular expression pattern modifier


    i (PCRE_CASELESS) If this modifier is set, the letters in the pattern will be case insensitive matching. m (PCRE_MULTILINE) By default, PCR E assumes that the target string consists of a single line of characters (but in fact it may contain multiple lines). The “head of line” metacharacter (^) matches only the beginning of the […]

  • Deep and shallow reflection


    At the beginning of the concept of contact reflex, the mechanism of sensory reflex is very complex and difficult to understand, so in this article, the reflection mechanism of Java is summarized by personal understanding. 1. What is reflection? What is reflection? It is said in the official documents that: Reflection is commonly used by […]

  • 1. Java Language Overview and Development Environment, the First Java Program


    Catalog: 1.1 JavaCharacteristic 1.2 JavaProgram Running Mechanism 1.3 Install JDl and configure environment variables 1.4 First JAVA program 1.5 The meaning of the first JAVA program Preface Java language has developed into a far-reaching programming language in the history of human computer. To some extent, it goes beyond the scope of programming language and becomes […]