Kotlin Sorting out interview questions

1, What is? kotlin

kotlin By JetBrains Developed static type programming language , Run in JVM upper .


2, Why Kotlin language

Kotlin Concise and efficient language , There is not so much redundant code , And it's empty and safe .


3, Explain extension function

extension Function is used to class Expand , Not from class derive


4,kotlin Empty security in null safety What do you mean?

The feature of null security is to avoid null pointer exceptions , It can also be used to distinguish between null and non null references .


5,kotlin Why and java Interoperability

Because for jvm Generally speaking, they are the same after compilation , After compilation byte code stay jvm Run on


6,kotlin Is there a ternary operator in



7,kotlin How to declare a variable in

var name: String


8,kotlin How many constructors are there

two types , One is primary Constructor , One is secondary Constructor


9, Say it kotlin Medium for Java.io.file Extension method of



10,kotlin How to handle null exceptions

use elvis The operator handles null exceptions ?: , ?. 


11, What are the characteristics ,kotlin Yes and java No,

null safety,operator overloading,coroutines, range expressions, smart cast,
compaion object


12,kotlin The role of data classes in

Data classes contain basic data types , However, it does not contain any function functions


13, Can put java Code conversion to kotlin Code

Can be in AndroidStudio perhaps JetBrains Intermediate conversion


14,kotlin allow macros Do you

kotlin Macros are not supported


15,kotlin Default behavior of class

kotlin The default is final of . because kotlin Support multiple class inheritance , Open classes cost more than final Class is much higher


16,kotlin Is the original data type supported

kotlin Raw data type is not supported


17, What is? range Operator

range The operator is used to traverse a range , Represented by two points

for(i in 1..5)



18,kotlin Of standards java Do libraries and classes provide additional functionality

kotlin The program is standard java On virtual machines , therefore kotlin and java There is no difference at this level ,java You can also directly kotlin Run in program


19, stay kotlin Define a volatile variable

volatile var x: Long? = null


20,kotlin What is the role of abstraction in

Abstract is the most important concept of object-oriented programming . Characteristics of abstract classes : Do you know what this class will do , But I don't know how to realize these functions and what functions to realize .


21,kotlin How to compare two strings




22, What is this code for

bar {



bar As a function , Receiving an expression as an argument , This expression prints a line of string


23,kotlin Higher order function


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