kotlin guide

a folder in which the war package will contain all dependent libraries (Java project depends on the most of the library is a jar package)In addition, I added the following in my gradle configuration file:apply plugin: "war"apply plugin: ‘application‘mainClassName = ‘com.ysl.jna.JnaApplicationKt‘(At the moment I don't know if it really works)The packaged operation is done here after you can choose the form you want to pack (or both forms of the package) after the package is finished, you will fi

until the completion of the process, corresponding to a stack frame in the virtual machine stack from the stack to the process.The Java Virtual machine stack holds local variable tables, such as the various basic data types known at compile time (Boolean, Byte, char, short, int, float, long, double), object reference (reference type, which is not equivalent to the object itself). Depending on the virtual machine implementation, it may be a reference pointer to the starting address of the object

Introduction to common operators and usages appearing in Kotlin . Operator Indicates that this object may be empty Add a question mark after the variable type, representing the variable as a nullable variable var name:string? = "Zhangsan" /** * If Str cannot be converted to INT type, then return null /Fun parseint (str:string): Int? { //(code slightly) } B?. Length//If B is non-null, return b.length, otherwise null, the type of the express

Kotlin commonly used operator 1, Elvis operator?: If the left expression is not empty, the Elvis operator returns the result on the left, otherwise it returns the result on the right.Note that the expression on the right only evaluates when the left side is empty Val a = b?. Length?:-1 //equivalent to: val a:int = if (b!= null) B.length else-12, safe conversion as? When using as transformation, classcastexception may often appear. So, now you can ma

Reference Official website class Defines a class by using the Class keyword. All classes in Kotlin inherit from any class, and the any class has only hashcode,tostring and equals three methods. A class is composed of the class name, the class header, and the body of the class-the main body of the class, which is wrapped up in braces-three parts. Where class headers, class bodies are optional. If there is no class body, the curly braces can be omitted.

Java. var and Val all member variables (including defined in the class and directly defined in the KT file) must be initialized when defined, and local variables (defined within the method) can be uninitialized. Such as: var s:string? = null var s2:string = "" Fun Main (args:arrayS,s2,test three variables in the above code must be initialized, but not m is not required. var: defines a variable variable. Val: Defining constants, the defined variables are final types. such as

Control Flow If expression In Kotlin, if is an expression that has a return value. But does not support three mesh operations Val A = 1 val b = 2 var max = a if (a If the if branch is a block of code, the last expression of the code block defaults to the return value Val max4 = if (a > B) { print ("Choose a") a } else { print ("Choose B") b } If an if expression returns a result or if an if expres

Arrays are represented by arrayThere are three ways to initialize a number group:var = arrayof (array1:arrayvar array2:arrayvar array3:arrayKotlin also has a specialized class with no boxing overhead to represent arrays of native types: ByteArray, Shortarray, Intarray, and so on. These classes and arrays have no inheritance relationships, but they have the same set of method properties.The array type of the basic type of Kotlin (number, character, Boo

parameter, but it is not the first parameter. When called, the parameter B is assigned by means of the parameter name = value, otherwise the assigned value is passed to the variable parameter a. To turn on the class of the KT file above, you can find that the corresponding Java code for this function is as follows: As you can see, variable parameter A has become a string array. Generic type Specify the generic type by Fun Main (args:arrayThis functionality is equivalent to extending the funct

When testing the Kotlin, we need a main function entry that is the same as the Java language, so be careful how you create it. Right-click Select the File type when you create a new item here.When you click OK, you create a. kt file that basically has nothing but a package xx.Then enter main return, the final generated main function: Fun Main (args:array After generating the main function, we can create the class directly in the current. kt file

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