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<!DOCTYPE html><html><head><script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script><script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script><script src="js/highlight.9.16.2.js"></script><script src="js/bootstrap.min.js"></script><script>hljs.initHighlightingOnLoad();</script><link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous"><link rel="stylesheet" href="css/style.css"><link rel="stylesheet" href="css/highlightjs-night-owl.css"><title>Kotlin vs Java</title><meta charset="utf-8"></head><body><div class="container-fluid text-center top-title"><div class="row text-center"><div class="col"><p>Kotlin vs Java</p></div></div></div><nav class="navbar navbar-dark navbar-expand-lg"><button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation"><span class="navbar-toggler-icon"></span></button><div id="navbarNav" class="collapse navbar-collapse"><ul class="navbar-nav"><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/index.html">Basics</a></li><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/classes.html">Classes</a></li><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/collections.html">Collections</a></li><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/concurrency.html">Concurrency</a></li><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/delegated-properties.html">Delegated Properties</a></li><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/dsl.html">DSL</a></li><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/functions.html">Functions</a></li><li class="nav-item px-2 active"><a class="nav-link" href="/kotlin-vs-java/scoping-functions.html">Scoping Functions</a><span class="sr-only"><current></current></span></li><li class="nav-item px-2"><a class="nav-link" href="/kotlin-vs-java/spring-framework.html">Spring Framework</a></li></ul></div></nav><a class="github-corner" href="https://github.com/driver733/kotlin-vs-java" aria-label="View source on Github"><svg width="80" height="80" viewBox="0 0 250 250" style="fill:#70B7FD; color:#fff; position: absolute; top: 0; border: 0; right: 0;" aria-hidden="true"><path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path><path class="octo-arm" d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2" fill="currentColor" style="transform-origin: 130px 106px;"></path><path class="octo-body" d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z" fill="currentColor"></path></svg><style>.github-corner:hover .octo-arm{animation:octocat-wave 560ms ease-in-out}@keyframes octocat-wave{0%,100%{transform:rotate(0)}20%,60%{transform:rotate(-25deg)}40%,80%{transform:rotate(10deg)}}@media (max-width:500px){.github-corner:hover .octo-arm{animation:none}.github-corner .octo-arm{animation:octocat-wave 560ms ease-in-out}}</style></a><div class="section"><div class="list-group-flush"><div class="list-group-item border-0"><div class="title">Also</div><div class="container-fluid"><div class="row"><div class="col"><div class="lang">Java</div><pre class="code"><code class="java">val original = "abc"
System.out.println(original);
System.out.println(new StringBuilder(input).reverse().toString());
System.out.println(original.length());</code></pre></div><div class="col"><div class="lang">Kotlin</div><pre class="code"><code class="kotlin">val original = "abc"
original.also {
println("The original String is $it") // "abc"
}.also {
println("The reverse String is ${it.reversed()}") // "cba"
}.also {
println("The length of the String is ${it.length}") // 3
}</code></pre></div></div></div></div><div class="list-group-item border-0"><div class="title">Apply</div><div class="container-fluid"><div class="row"><div class="col"><div class="lang">Java</div><pre class="code"><code class="java">public MyFragment createInstance(Bundle args) {
val fragment = new MyFragment()
fragment.setArguments(args)
return fragment
}
</code></pre></div><div class="col"><div class="lang">Kotlin</div><pre class="code"><code class="kotlin">fun createInstance(args: Bundle) = MyFragment().apply { arguments = args }</code></pre></div></div></div></div><div class="list-group-item border-0"><div class="title">Let</div><div class="container-fluid"><div class="row"><div class="col"><div class="lang">Java</div><pre class="code"><code class="java">val original = "abc"
// Map the value and send to the next chain
Optional.of(original)
.map(
str -> {
System.out.println("The original String is " + str); // "abc"
val result = new StringBuilder(input).reverse().toString();
return result;
}
).map(
reversed -> {
System.out.println("The reverse String is " + reversed); // "cba"
val result = reversed.length();
return result;
}
).map(
length -> {
System.out.println("The length of the String is " + length); // 3
return length;
}
)</code></pre></div><div class="col"><div class="lang">Kotlin</div><pre class="code"><code class="kotlin">val original = "abc"
// Map the value and send to the next chain
original.let {
println("The original String is $it") // "abc"
it.reversed() // map it as parameter to send to next let
}.let {
println("The reverse String is $it") // "cba"
it.length // can be evolved to other type
}.let {
println("The length of the String is $it") // 3
}</code></pre></div></div></div></div><div class="list-group-item border-0"><div class="title">Let and apply</div><div class="container-fluid"><div class="row"><div class="col"><div class="lang">Java</div><pre class="code"><code class="java">public File makeDir(String path) {
val result = new File(path)
result.mkdirs()
return result
}</code></pre></div><div class="col"><div class="lang">Kotlin</div><pre class="code"><code class="kotlin">fun makeDir(path: String) =
path.let { File(it) }
.also { it.mkdirs() }</code></pre></div></div></div></div><div class="list-group-item border-0"><div class="title">Run</div><div class="container-fluid"><div class="row"><div class="col"><div class="lang">Java</div><pre class="code"><code class="java">if (webview.settings != null) {
val settings = webview.settings
settings.javaScriptEnabled = true
settings.databaseEnabled = true
}</code></pre></div><div class="col"><div class="lang">Kotlin</div><pre class="code"><code class="kotlin">webview.settings?.run {
javaScriptEnabled = true
databaseEnabled = true
}</code></pre></div></div></div></div><div class="list-group-item border-0"><div class="title">TakeIf</div><div class="container-fluid"><div class="row"><div class="col"><div class="lang">Java</div><pre class="code"><code class="java">public void displaySubstringPosition(String input, String sub) {
val index = input.indexOf(sub)
if (index >= 0) {
System.out.println("The substring " + sub + "is found in " + input + ".")
System.out.println("Its start position is " + index + ".")
}
}</code></pre></div><div class="col"><div class="lang">Kotlin</div><pre class="code"><code class="kotlin">fun displaySubstringPosition(input: String, sub: String) {
input.indexOf(sub).takeIf { it >= 0 }?.let {
println("The substring $sub is found in $input.")
println("Its start position is $it.")
}
}</code></pre></div></div></div></div><div class="list-group-item border-0"><div class="title">With</div><div class="container-fluid"><div class="row"><div class="col"><div class="lang">Java</div><pre class="code"><code class="java">val numbers = List.of("one", "two", "three")
with(numbers) {
val firstItem = numbers.get(0)
val lastItem = numbers.get(numbers.size() - 1)
System.out.println("First item: " + firstItem + ", last item: " + lastItem)
}</code></pre></div><div class="col"><div class="lang">Kotlin</div><pre class="code"><code class="kotlin">val numbers = mutableListOf("one", "two", "three")
with(numbers) {
val firstItem = first()
val lastItem = last()
println("First item: $firstItem, last item: $lastItem")
}</code></pre></div></div></div></div></div></div><footer><div class="container-fluid text-center"><div class="row pt-4 pb-1"><div class="col"><span class="align-middle">Created by:<a href="https://www.driver733.com"> @driver733</a></span></div></div><div class="row pb-4 pt-1"><div class="col"><span class="align-middle">Based on:<a href="https://github.com/fabiomsr/from-java-to-kotlin"> fabiomsr/from-java-to-kotlin</a></span></div></div></div></footer></body></html>