如何在 Java 8 中从 Stream 获取数组列表

原文:https://www . geesforgeks . org/how-to-ArrayList-from-stream-in-Java-8/

给定一个流，任务是将这个流转换成 Java 8 中的数组列表。

示例:

Input: Stream: [1, 2, 3, 4, 5]
Output: ArrayList: [1, 2, 3, 4, 5]

Input: Stream: ['G', 'e', 'e', 'k', 's']
Output: ArrayList: ['G', 'e', 'e', 'k', 's']

1. Using Collectors.toList() method:

   1. 获取要转换的流。
   2. 使用 Collect()和 Collectors.toList()方法将流收集为列表。
   3. 将此列表转换为数组列表
   4. 返回/打印数组列表

   下面是上述方法的实现:

   程序:

   ```java // Java program to convert Stream to ArrayList // using Collectors.toList() method

   import java.util.; import java.util.stream.;

   public class GFG {

   // Function to get ArrayList from Stream     public static ArrayList     getArrayListFromStream(Stream stream)     {

   // Convert the Stream to List         List             list = stream.collect(Collectors.toList());

   // Create an ArrayList of the List         ArrayList             arrayList = new ArrayList(list);

   // Return the ArrayList         return arrayList;     }

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

   Stream             stream = Stream.of(1, 2, 3, 4, 5);

   // Convert Stream to ArrayList in Java         ArrayList             arrayList = getArrayListFromStream(stream);

   // Print the arraylist         System.out.println("ArrayList: " + arrayList);     } } ```

   Output:

   ```java ArrayList: [1, 2, 3, 4, 5]

   ```

2. Using Collectors.toCollection() method: Approach:

   1. 获取要转换的流。
   2. 使用 Collect()和 Collectors.toCollection()方法将流收集为数组列表。
   3. 返回/打印数组列表

   下面是上述方法的实现:

   程序:

   ```java // Java program to convert Stream to ArrayList // using Collectors.toList() method

   import java.util.; import java.util.stream.;

   public class GFG {

   // Function to get ArrayList from Stream     public static ArrayList     getArrayListFromStream(Stream stream)     {

   // Convert the Stream to ArrayList         ArrayList             arrayList = stream                             .collect(Collectors                             .toCollection(ArrayList::new));

   // Return the ArrayList         return arrayList;     }

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

   Stream             stream = Stream.of(1, 2, 3, 4, 5);

   // Convert Stream to ArrayList in Java         ArrayList             arrayList = getArrayListFromStream(stream);

   // Print the arraylist         System.out.println("ArrayList: "                            + arrayList);     } } ```

   Output:

   ```java ArrayList: [1, 2, 3, 4, 5]

   ```

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