在 Java 中将迭代器转换为可迭代的

原文:https://www . geesforgeks . org/convert-iterator-to-iteratable-in-Java/

给定一个迭代器，任务是将其转换为 Java 中的 Iterables。

示例:

Input: Iterator = {1, 2, 3, 4, 5}
Output: {1, 2, 3, 4, 5}

Input: Iterator = {'G', 'e', 'e', 'k', 's'}
Output: {'G', 'e', 'e', 'k', 's'}

以下是各种方法:

• By overriding the abstract method Iterable.iterator():

  1. 获取迭代器。
  2. 重写 Iterable.iterator()方法并获取 Iterable。
  3. 返回 Iterable。

  下面是上述方法的实现:

  ```java // Java program to get a Iterable // from a given Iterator

  import java.util.*;

  class GFG {

  // Function to get the Spliterator     public static Iterable     getIterableFromIterator(Iterator iterator)     {         return new Iterable() {             @Override             public Iterator iterator()             {                 return iterator;             }         };     }

  // Driver code     public static void main(String[] args)     {

  // Get the Iterator         Iterator             iterator = Arrays.asList(1, 2, 3, 4, 5)                            .iterator();

  // Get the Iterable from the Iterator         Iterable             iterable = getIterableFromIterator(iterator);

  // Print the elements of Iterable         iterable.forEach(System.out::println);     } } ```

  Output:

  ```java 1 2 3 4 5

  ```

• Using Java 8 lambda expression:

  1. 获取迭代器。
  2. 使用 Lambda 表达式将迭代器转换为可迭代的。
  3. 返回 Iterable。

  下面是上述方法的实现:

  ```java // Java program to get an Iterable // from a given Iterator

  import java.util.*;

  class GFG {

  // Function to get the Spliterator     public static Iterable     getIterableFromIterator(Iterator iterator)     {         return () -> iterator;     }

  // Driver code     public static void main(String[] args)     {

  // Get the Iterator         Iterator             iterator = Arrays.asList(1, 2, 3, 4, 5)                            .iterator();

  // Get the Iterable from the Iterator         Iterable             iterable = getIterableFromIterator(iterator);

  // Print the elements of Iterable         iterable.forEach(System.out::println);     } } ```

  Output:

  ```java 1 2 3 4 5

  ```

• Using Spliterators:

  1. 获取迭代器。
  2. 使用 spliterators . spliteratorrunknownsize()方法将迭代器转换为 Spliterator。
  3. 使用 StreamSupport.stream()方法将拆分器转换为顺序流。
  4. 使用 Collect()方法将顺序流的元素收集为可迭代的。
  5. 返回 Iterable。

  下面是上述方法的实现:

  ```java // Java program to get a Iterable // from a given Iterator

  import java.util.*; import java.util.stream.Collectors; import java.util.stream.StreamSupport;

  class GFG {

  // Function to get the Spliterator     public static Iterable     getIterableFromIterator(Iterator iterator)     {         return StreamSupport

  // Convert the iterator into a Spliterator             // and then into a sequential stream             .stream(Spliterators.spliteratorUnknownSize(iterator, 0),                     false)

  // Convert the stream to an iterable             .collect(Collectors.toList());     }

  // Driver code     public static void main(String[] args)     {

  // Get the Iterator         Iterator             iterator = Arrays.asList(1, 2, 3, 4, 5)                            .iterator();

  // Get the Iterable from the Iterator         Iterable             iterable = getIterableFromIterator(iterator);

  // Print the elements of Iterable         iterable.forEach(System.out::println);     } } ```

  Output:

  ```java 1 2 3 4 5

  ```

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