Class, interface, function

Preface

Various technical terms are increasing , To learn programming well, you must first understand technical terms , Then we can make a general judgment on the technology industry as a whole . It is often used for a certain knowledge point in learning, but it is easy to be confused when reading official documents , The corresponding relationship between professional terms and their own knowledge .blog Lie in listing java and kotlin , class 、 Interface 、 function species .

function

Lambda It's an object .

Lambda An expression is a function interface object
lambda expression :block:String.()->Unit

kotlin inline keyword

Every time a higher-order function is called , Will create an anonymous inner class . The function is set to Inline after . The expression of the function will be embedded in the called place at compile time , Achieve the effect of performance optimization . Reduce class loading opportunities .

inline keyword Function compared with ordinary function bytecode and found ：

1. Use inline after The number of bytecode lines is reduced relative to non inline The bytecode class of the function
2. Use inline There will be no... In bytecode kotlin/jvm/lambda Class inheritance , Ordinary functions have inheritance kotlin/jvm/lambda .

Intelj IDE Check bytecode （java and kotlin The way ）

kotlin Check bytecode

Kotlin Function type ： Function types have a pair of parentheses , And it has a return value

expression （Int）->Unit

Functional expression （SAM） Interface

An interface with only one abstract method is called a functional interface or SAM（ A single abstract method ） Interface . A functional interface can have multiple non abstract members , But there can only be one abstract member .

Statement ：

fun interface KRunnable {
    
   fun invoke()
}

Functional interface conversion ： Lambda conversion SAM

problem ：

1. What is bytecode
2. Basic knowledge of bytecode
3. Higher order functions and Lambda expression

Java Lambda and Kotlin Lambda The difference between