Groovy & Gradle: JVM Automation and Build Engineering · Pelajaran

Penyempurnaan Koleksi Groovy

Temukan tambahan canggih Groovy untuk koleksi Java yang membuat manipulasi data menjadi lebih sederhana dan ekspresif.

Penyempurnaan Koleksi Groovy adalah pelajaran Groovy & Gradle: JVM Automation and Build Engineering gratis di CoddyKit. Ini adalah pelajaran 1 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Groovy & Gradle: JVM Automation and Build Engineering, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Groovy & Gradle: JVM Automation and Build Engineering mencakup 4 pelajaran total.

Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.

Groovy's Collection Power-Up

Groovy supercharges Java's standard collections (List, Map, Set) with many new, convenient methods. This makes your code shorter, more readable, and much more expressive.

You'll spend less time writing boilerplate and more time solving problems!

Easy List Initialization

Creating and populating lists in Groovy is a breeze. No need for new ArrayList<>() or repetitive add() calls. Just use square brackets []!

class Main {
  static void main(String[] args) {
    def numbers = [1, 2, 3, 4, 5]
    def names = ["Alice", "Bob", "Charlie"]
    println "Numbers: " + numbers
    println "Names: " + names
  }
}

The Versatile `each` Method

The each method is your go-to for iterating over collections. It's concise and works with both Lists and Maps.

For lists, it's like a simplified loop. For maps, it iterates over entries.

class Main {
  static void main(String[] args) {
    def fruits = ["Apple", "Banana", "Cherry"]
    fruits.each { fruit ->
      println "I love " + fruit
    }
  }
}

Transforming Lists with `collect`

The collect method creates a new list by transforming each element of the original list. It's perfect for mapping items to new values.

class Main {
  static void main(String[] args) {
    def numbers = [1, 2, 3]
    def doubledNumbers = numbers.collect { it * 2 }
    println "Original: " + numbers
    println "Doubled: " + doubledNumbers
  }
}

Filtering Elements with `findAll`

Need to select elements that meet specific criteria? Use findAll. It returns a new list containing only the elements for which the closure evaluates to true.

class Main {
  static void main(String[] args) {
    def ages = [12, 18, 25, 7, 30]
    def adults = ages.findAll { it >= 18 }
    println "Ages: " + ages
    println "Adults: " + adults
  }
}

Counting Matching Elements

The count method helps you quickly determine how many elements in a collection satisfy a given condition. It returns a single integer.

class Main {
  static void main(String[] args) {
    def scores = [85, 92, 78, 95, 88]
    def highScores = scores.count { it > 90 }
    println "Scores: " + scores
    println "Number of high scores (>90): " + highScores
  }
}

Simplified Map Syntax

Groovy makes creating maps incredibly easy using square brackets [] and colons : for key-value pairs. Keys can often be unquoted strings.

class Main {
  static void main(String[] args) {
    def person = [name: "Anna", age: 30, city: "New York"]
    println "Person: " + person
    println "Name: " + person.name // Property-style access
    println "Age: " + person["age"] // Map-style access
  }
}

Iterating Over Maps

Just like lists, maps can be iterated using each. The closure for maps typically takes two arguments: key and value.

You can also use eachWithIndex if you need the index.

class Main {
  static void main(String[] args) {
    def config = [mode: "dev", port: 8080]
    config.each { key, value ->
      println "${key}: ${value}"
    }
  }
}

Accessing Properties with Spread `*.`

The spread operator *. is a powerful Groovy feature for collections. It applies a property access or method call to all elements in a collection, returning a new list of results.

class Person {
  String name
  int age
}

class Main {
  static void main(String[] args) {
    def people = [
      new Person(name: "Alice", age: 25),
      new Person(name: "Bob", age: 30)
    ]
    def names = people*.name
    println "People names: " + names
  }
}

Collection Challenge

Consider the following Groovy code snippet:

def items = [10, 25, 30, 45, 50]
def result = items.findAll { it > 20 }.collect { it / 5 }
println result

What will be the output of this code?

Recap: Groovy's Collection Power

You've explored how Groovy significantly enhances standard Java collections. We covered:

Simplified List and Map creation.
Powerful iteration with each.
Transforming collections with collect.
Filtering with findAll and counting with count.
The convenient Spread Operator *. for bulk property access.

These features make working with data structures in Groovy much more efficient and enjoyable!

Pertanyaan yang Sering Diajukan

Apakah pelajaran “Penyempurnaan Koleksi Groovy” gratis?

Ya — teks lengkap “Penyempurnaan Koleksi Groovy” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Groovy & Gradle: JVM Automation and Build Engineering, upgrade ke CoddyKit PRO. Kursus Groovy & Gradle: JVM Automation and Build Engineering mencakup 4 pelajaran total.

Apa yang akan aku pelajari di “Penyempurnaan Koleksi Groovy”?

Temukan tambahan canggih Groovy untuk koleksi Java yang membuat manipulasi data menjadi lebih sederhana dan ekspresif. Kamu berlatih Groovy & Gradle: JVM Automation and Build Engineering dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.

Apakah aku perlu pengalaman untuk memulai Groovy & Gradle: JVM Automation and Build Engineering?

Tidak diperlukan pengalaman sebelumnya. Groovy & Gradle: JVM Automation and Build Engineering di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 1 dari 4.

Berapa lama pelajaran “Penyempurnaan Koleksi Groovy” memakan waktu?

Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.

Bisakah aku menulis dan menjalankan kode dalam pelajaran Groovy & Gradle: JVM Automation and Build Engineering ini?

Ya. Setiap pelajaran Groovy & Gradle: JVM Automation and Build Engineering menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.

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