Kotlin静态方法和变量 [英] Kotlin static methods and variables

问题描述

我希望能够将类实例保存到公共静态变量，但是我不知道如何在Kotlin中做到这一点.

I want to be able to save a class instance to a public static variable but I can't figure out how to do this in Kotlin.

class Foo {

    public static Foo instance;
    public Foo() {
        instance = this;
    }

}

推荐答案

与Java静态字段最接近的东西是伴随对象.您可以在此处找到有关它们的文档参考: https://kotlinlang.org /docs/reference/object-declarations.html#companion-objects

The closest thing to Java's static fields is a companion object. You can find the documentation reference for them here: https://kotlinlang.org/docs/reference/object-declarations.html#companion-objects

您在Kotlin中的代码如下所示:

Your code in Kotlin would look something like this:

class Foo {

    companion object {
        lateinit var instance: Foo
    }

    init {
        instance = this
    }

}

如果要将字段/方法以静态形式公开给Java调用者，则可以应用

If you want your fields/methods to be exposed as static to Java callers, you can apply the @JvmStatic annotation:

class Foo {

    companion object {
        @JvmStatic lateinit var instance: Foo
    }

    init {
        instance = this
    }

}

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