Java 中的 Stream.distinct()

原文:https://www.geeksforgeeks.org/stream-distinct-java/

distinct() 返回由流中不同元素组成的流。distinct()是流界面的方法。该方法使用 hashCode() 和 equals() 方法获取不同的元素。在有序流的情况下，不同元素的选择是稳定的。但是，在无序流的情况下，不同元素的选择不一定是稳定的，可能会发生变化。distinct()执行有状态中间操作，即它在内部保持某种状态来完成操作。

语法:

Stream<T> distinct()

Where, Stream is an interface and the function
returns a stream consisting of the distinct 
elements.

下面给出了一些例子，以便更好地理解函数的实现。 例 1 :

// Implementation of Stream.distinct()
// to get the distinct elements in the List
import java.util.*;

class GFG {

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

        // Creating a list of integers
        List<Integer> list = Arrays.asList(1, 1, 2, 3, 3, 4, 5, 5);

        System.out.println("The distinct elements are :");

        // Displaying the distinct elements in the list
        // using Stream.distinct() method
        list.stream().distinct().forEach(System.out::println);
    }
}

输出:

The distinct elements are :
1
2
3
4
5

例 2 :

// Implementation of Stream.distinct()
// to get the distinct elements in the List
import java.util.*;

class GFG {

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

        // Creating a list of strings
        List<String> list = Arrays.asList("Geeks", "for", "Geeks",
                                          "GeeksQuiz", "for", "GeeksforGeeks");

        System.out.println("The distinct elements are :");

        // Displaying the distinct elements in the list
        // using Stream.distinct() method
        list.stream().distinct().forEach(System.out::println);
    }
}

输出:

The distinct elements are :
Geeks
for
GeeksQuiz
GeeksforGeeks

例 3 :

// Implementation of Stream.distinct()
// to get the count of distinct elements
// in the List
import java.util.*;

class GFG {

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

        // Creating a list of strings
        List<String> list = Arrays.asList("Geeks", "for", "Geeks",
                                          "GeeksQuiz", "for", "GeeksforGeeks");

        // Storing the count of distinct elements
        // in the list using Stream.distinct() method
        long Count = list.stream().distinct().count();

        // Displaying the count of distinct elements
        System.out.println("The count of distinct elements is : " + Count);
    }
}

输出:

The count of distinct elements is : 4

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