kotlin var，val，const val修饰符编译

前言

kotlin的var,val,const的区别网上有很多的文章了，但是这些关键字在companion object和top-level情况下的多种情况又是怎么样的？本文通过编译成Java代码来探讨

kotlin类中var val const编译情况

class MyTest{
	var test0: String = "aaa"
	// 编译后:private String test0 = "aaa";

    @JvmField var test1: String = "aaa"
    // 编译后:public String test1 = "aaa";

    val test2:String = "aaa"
	// 编译后:private final String test2 = "aaa";
	
    @JvmField val test3:String = "aaa"
    // 编译后:public final String test3 = "aaa";
}

kotlin companion object 中var val const编译情况

class MyTest{
	companion object{
		var test4:String = "aaa"
		// 编译后:private static String test4 = "aaa";

        @JvmField var test5:String = "aaa"
        // 编译后:public static String test5 = "aaa";

        val test6:String = "aaa"
        // 编译后:private static final String test6 = "aaa";

        @JvmField val test7: String = "aaa"
        // 编译后:public static final String test7 = "aaa";

        const val test8:String = "aaa"
        // 编译后:public static final String test8 = "aaa";
	}
}

kotlin top-level 中var val const编译情况

var test9: String = "aaa"
// 编译后: private static String test9 = "aaa";

@JvmField var test10: String = "aaa"
// 编译后: public static String test10 = "aaa";

val test11: String = "aaa"
// 编译后: private static final String test11 = "aaa";

@JvmField val test12: String = "aaa"
// 编译后: public static final String test12 = "aaa";

const val test13:String = "aaa"
// 编译后: public static final String test13 = "aaa";

以上是var val const val在companion object,top-level情况下编译结果。
对于以上的结果，可以总结下:

1. var：被private修饰，提供public的setter和getter相关方法
2. val：被private final修饰，提供public的getter相关方法
3. const val：被public static final修饰(只能用于top-level，object和companion object)
4. companion object，object和top-level：加上static修饰
5. @JvmField：加上public修饰