操作符 - 调用Java或JVM语言编写的代码引起的NullPointerException- There's some data inconsistency with regard toinitialization(an uninitialized this available in a constructor is used somewhere) 最后一条是借用Kotlin官方的原话哦~ 在Kotlin的类型系统中,类型被分成可以使用null的引用和不能使用null的引用。比如...
In this tutorial we will discuss about one of the most important features of Kotlin:Null Safety.In programming world when a variable doesn't refer to anything then it is considered asnull. If we try to use this variable then we will getNullPointerExceptionor NPE. Let us see a small examp...
在Java 中,null 的引用一般就等同于一个空指针异常 NullPointerException 。空指针异常成为大部分 Java 开发的应用程序崩溃的首要原因了,防不胜防啊,指不定什么时候就出一个 null 出来了,以至于程序中有大量的if(a == null) 之类的判断。 在Kotlin 的设计就是为了避免出现没有空指针的,但是有一些情况下,你还...
对于Null 的检查是 Kotlin 的特点之一。强制你在编码过程中考虑变量是否可为 null,因此可以避免很多在 Java 中隐藏的 NullPointerException。 但是,当你用插件直接将 Java 代码转换为 Kotlin 时,你会发现有很多 !! 在里面。但其实 !! 意味着「有一个潜在未处理的 KotlinNullPointerException 在这里」。 这里就介...
Kotlin- 空安全(Null Safety) 可为空的类型和非空类型 Kotlin的类型系统旨在消除在代码中引用空引用的危险。 在很多语言中都有一个陷阱,包括Java,访问空引用的成员就会导致空引用异常,在java中就是等价于NullPointerException异常. Kotlin的类型系统会在我们的代码尽量消除空指针异常,引起空指针异常的情况可能是以下...
In this tutorial, we’ll take a look at the need to check fornullin Java and various alternatives that help us to avoidnullchecks in our code. Further reading: 2. What IsNullPointerException? According to theJavadoc forNullPointerException, it’s thrown when an application attempts to usenu...
尝试兼容Java的其他JVM 语言 比如 Kotlin —— Kotlin 设计了一套处理 null 的机制(本质上不变)简化了防御性的代码的编写https://kotlinlang.org/docs/reference/null-safety.html 关于为什么会有NullPointerExeception的设计的探讨到这里就结束了,但基于这个问题希望能引起读者(尤其是新手程序员)的注意 ——不要忽...
The Root of the Problem: Java Weak Type Safety Have you heard of Compile Type Safety? If notin this article you can findout what it is and what is the difference between Compile-Time and Type Safety. Java provides Compile Type Safety and it gives a guarantee to the developer that he ca...
NullPointerExceptionis the most common exception developers face. There are several convenient ways to ensurenullsafety. Java APIs and external libraries provide many techniques. However, there’s nothing shameful to fall back to simpleifstatements, as it’s clean, simple, and explicit. ...
程序员通常说的NullPointerExeception来自于Javahttps://docs.oracle.com/javase/8/docs/api/java/lang/NullPointerException.html 官方文档的描述是: Thrown when an application attempts to use null in a case where an object is required. These include: ...