diff --git a/core-kotlin/src/main/kotlin/com/baeldung/lambda/Lambda.kt b/core-kotlin/src/main/kotlin/com/baeldung/lambda/Lambda.kt new file mode 100644 index 0000000000..f35f9cdac2 --- /dev/null +++ b/core-kotlin/src/main/kotlin/com/baeldung/lambda/Lambda.kt @@ -0,0 +1,84 @@ +package com.baeldung.lambda + +fun inferredType(input: Int): Int { + val square = { number: Int -> number * number } + + return square(input) +} + +fun intToBiggerString(argument: Int): String { + + val magnitude100String = { input: Int -> + val magnitude = input * 100 + magnitude.toString() + } + + return magnitude100String(argument) +} + +fun manyLambda(nums: Array): List { + val newList = nums.map { intToBiggerString(it) } + + return newList +} + +fun empty() { + val noReturn: (Int) -> Unit = { num -> println(num) } + + noReturn(5) +} + +fun invokeLambda(lambda: (Double) -> Boolean): Boolean { + return lambda(4.329) +} + +fun extendString(arg: String, num: Int): String { + val another: String.(Int) -> String = { this + it } + + return arg.another(num) +} + +fun getCalculationLambda(): (Int) -> Any { + val calculateGrade = { grade: Int -> + when (grade) { + in 0..40 -> "Fail" + in 41..70 -> "Pass" + in 71..100 -> "Distinction" + else -> false + } + } + + return calculateGrade +} + +fun getCalculationLambdaWithReturn(): (Int) -> String { + val calculateGrade: Int.() -> String = lambda@{ + if (this < 0 || this > 100) { + return@lambda "Error" + } else if (this < 40) { + return@lambda "Fail" + } else if (this < 70) { + return@lambda "Pass" + } + + "Distinction" + } + + return calculateGrade +} + +fun getCalculationAnonymousFunction(): (Int) -> String { + val calculateGrade = fun(grade: Int): String { + if (grade < 0 || grade > 100) { + return "Error" + } else if (grade < 40) { + return "Fail" + } else if (grade < 70) { + return "Pass" + } + + return "Distinction" + } + + return calculateGrade +} \ No newline at end of file diff --git a/core-kotlin/src/test/java/com/baeldung/lambda/LambdaKotlinTest.java b/core-kotlin/src/test/java/com/baeldung/lambda/LambdaKotlinTest.java new file mode 100644 index 0000000000..1e68d8af4c --- /dev/null +++ b/core-kotlin/src/test/java/com/baeldung/lambda/LambdaKotlinTest.java @@ -0,0 +1,36 @@ +package com.baeldung.lambda; + +import kotlin.jvm.functions.Function1; +import org.junit.jupiter.api.Test; + +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertTrue; + +/** + * Created by Paul Jervis on 24/04/2018. + */ +class LambdaKotlinTest { + + @Test + void givenJava6_whenUsingAnonnymousClass_thenReturnLambdaResult() { + assertTrue(LambdaKt.invokeLambda(new Function1() { + @Override + public Boolean invoke(Double c) { + return c >= 0; + } + })); + } + + @Test + void givenJava8_whenUsingLambda_thenReturnLambdaResult() { + assertTrue(LambdaKt.invokeLambda(c -> c >= 0)); + } + + @Test + void givenJava8_whenCallingMethodWithStringExtension_thenImplementExtension() { + String actual = LambdaKt.extendString("Word", 90); + String expected = "Word90"; + + assertEquals(expected, actual); + } +} diff --git a/core-kotlin/src/test/kotlin/com/baeldung/lambda/LambdaTest.kt b/core-kotlin/src/test/kotlin/com/baeldung/lambda/LambdaTest.kt new file mode 100644 index 0000000000..3af00c98ff --- /dev/null +++ b/core-kotlin/src/test/kotlin/com/baeldung/lambda/LambdaTest.kt @@ -0,0 +1,95 @@ +package com.baeldung.lambda + +import org.junit.jupiter.api.Assertions.assertFalse +import org.junit.jupiter.api.Assertions.assertTrue +import org.junit.jupiter.api.Test +import kotlin.test.assertEquals + +class LambdaTest { + @Test + fun whenCallingALambda_thenPerformTheAction() { + assertEquals(9, inferredType(3)) + } + + @Test + fun whenCallingAMoreComplicatedLambda_thenPerformTheAction() { + assertEquals("500", intToBiggerString(5)) + } + + @Test + fun whenPassingALambdaObject_thenCallTriggerLambda() { + val lambda = { arg: Double -> + arg == 4.329 + } + + val result = invokeLambda(lambda) + + assertTrue(result) + } + + @Test + fun whenPassingALambdaLiteral_thenCallTriggerLambda() { + val result = invokeLambda({ + true + }) + + assertTrue(result) + } + + @Test + fun whenPassingALambdaLiteralOutsideBrackets_thenCallTriggerLambda() { + val result = invokeLambda { arg -> arg.isNaN() } + + assertFalse(result) + } + + @Test + fun whenPassingAnAnonymousFunction_thenCallTriggerLambda() { + val result = invokeLambda(fun(arg: Double): Boolean { + return arg >= 0 + }) + + assertTrue(result) + } + + @Test + fun whenUsingLambda_thenCalculateGrade() { + val gradeCalculation = getCalculationLambda() + + assertEquals(false, gradeCalculation(-40)) + assertEquals("Pass", gradeCalculation(50)) + } + + @Test + fun whenUsingReturnStatementLambda_thenCalculateGrade() { + val gradeCalculation: Int.() -> String = getCalculationLambdaWithReturn() + + assertEquals("Distinction", 80.gradeCalculation()) + assertEquals("Error", 244_234_324.gradeCalculation()) + } + + @Test + fun whenUsingAnonymousFunction_thenCalculateGrade() { + val gradeCalculation = getCalculationAnonymousFunction() + + assertEquals("Error", gradeCalculation(244_234_324)) + assertEquals("Pass", gradeCalculation(50)) + } + + @Test + fun whenPassingAFunctionReference_thenCallTriggerLambda() { + val reference = Double::isFinite + val result = invokeLambda(reference) + + assertTrue(result) + } + + @Test + fun givenArray_whenMappingArray_thenPerformCalculationOnAllElements() { + val expected = listOf("100", "200", "300", "400", "500") + val actual = manyLambda(arrayOf(1, 2, 3, 4, 5)) + + assertEquals(expected, actual) + } + +} \ No newline at end of file