val hello : String = "Hello Kotlin" ```kotlin var 定义变量 和 Java 中声明的变量一样 ```kotlin var hello : String = "Hello Kotlin" 1. 2. 3. 4. 5. String定义了数据类型,Kotlin支持类型推断,可以省略 val hello = "Hello Kotlin" var hello = "Hello Kotlin" 1. 2. 4. 空指针安全 用?
第一步:我们首先应该将kotlin的插件导入Android Studio,如果你用的是Android Studio3.0或更高版本这一步你可以跳过 第二步:我们需要在gradle中添加以下代码(下面是我gradle的配置): buildscript { ext.kotlin_version = '1.0.0' repositories { jcenter() } dependencies { classpath 'com.android.tools.build:grad...
data class就是一个类中只包含一些数据字段,类似于vo,pojo,javabean。一般而言,我们在Java中定义了这个数据类之后要重写一下toString,equals等方法。要生成get,set方法。 然而在Kotlin中这些都不在需要自己手动去敲了,编译器在背后默默给我们生成了如下的东西: equals()/hashCode() toString()方法 componentN()方法 ...
classUser(varname:String,varage:Int){override funtoString():String{return"User(name='$name', age=$age)"}} 细看Java中也是如此写法,但是当类的属性值特别多的时候,toString()内容也会异常的多 Kotlin则提供data class的方式来解决这个问题: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 dataclass...
A data class in Kotlin is created with thedata classkeywords. The data classes must follow a couple of rules. The primary constructor needs to have at least one parameter. All primary constructor parameters must be marked as val or var. The data classes cannot be abstract, open, sealed or...
The base class has anopenmodifier, as classes in Kotlin are final by default. Additionally,both fields are open, as we’ll overwrite them in our data class. Let’s now create the data class: data class CarExtendingVehicle(override val age: Int, override val numberOfWheels: Int, val numbe...
Kotlin Classes and Objects Data Class Definition reference 1. Overview The Kotlin language has introduced the concept of Data Classes, whose main purpose is to simply hold data without the boilerplate code needed in Java to create a POJO. Simply put, Kotlin’s solution enables us to avoid writ...
Gson是Android解析Json的老牌子了,它的使用和原理也被大家研究的极其透彻了,可以说这是一个相当成熟的库。但是伴随kotlin的普及,有一个问题也越发明显地暴露了出来。 kotlin里有一个 data class 的概念,倒不是什么“黑科技”的东西,但是确实相当好用,它会自动生成hashcode、equals以及toString等方法,都是对于一个bea...
//Following is printed in the console. //Book(name=Android tutorials, authorName=Anupam, lastModified=1234567, rating=4.5, downloads=1000) //Book(name=Kotlin, authorName=Anupam, lastModified=1234567, rating=4.5, downloads=1000) Kotlin Data Class equals() and hashCode() ...
19 + classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.32' 20 20 } 21 21 } 22 22 library/build.gradle +6-3 Original file line numberDiff line numberDiff line change @@ -1,12 +1,13 @@ 1 1 apply plugin: 'com.android.library' 2 + apply plugin: 'kotlin-android...