Introspection: Difference between revisions

=={{header|Kotlin}}==

We will use Java reflection for this task as Kotlin's own reflection facilities do not appear to be able to deal generically with top-level entities at the present time (i.e. ::class isn't yet supported):

<lang scala>// version 1.0.6 (intro.kt)

import java.lang.reflect.Method

val bloop = -3

val i = 4

val j = 5

val k = 6

fun main(args: Array<String>) {

// get version of JVM

val version = System.getProperty("java.version")

if (version >= "1.6") println("The current JVM version is $version")

else println("Must use version 1.6 or later")

// check that 'bloop' and 'Math.abs' are available

// note that the class created by the Kotlin compiler for top level declarations will be called 'IntroKt'

val topLevel = Class.forName("IntroKt")

val math = Class.forName("java.lang.Math")

val abs = math.getDeclaredMethod("abs", Int::class.java)

val methods = topLevel.getDeclaredMethods()

for (method in methods) {

// note that the read-only Kotlin property 'bloop' is converted to the static method 'getBloop' in Java

if (method.name == "getBloop" && method.returnType == Int::class.java) {

println("\nabs(bloop) = ${abs.invoke(null, method.invoke(null))}")

break

}

}

// now get the number of global integer variables and their sum

var count = 0

var sum = 0

for (method in methods) {

if (method.returnType == Int::class.java) {

count++

sum += method.invoke(null) as Int

}

}

println("\nThere are $count global integer variables and their sum is $sum")

}</lang>

{{out}}

<pre>

The current JVM version is 1.8.0_121

abs(bloop) = 3

There are 4 global integer variables and their sum is 12

</pre>