Java Stream.concat()

来源：这里教程网时间：2026-02-17 21:12:33 作者：

Java Stream.concat()

Stream.concat()方法创建一个连接的流，其中的元素是第一个流的所有元素，然后是第二个流的所有元素。如果两个输入流都是有序的，那么生成的流就是有序的，如果其中一个输入流是平行的，那么生成的流就是平行的。

语法:

static <T> Stream<T> concat(Stream<? extends T > stream1,                             Stream<? extends T > stream2)

其中，T是流元素的类型。
stream1代表第一个流。
stream2代表第二个流，并且
该函数返回两个输入流的连接值
两个输入流的连接

对Stream.concat(stream1, stream2)的调用可以被认为是形成了一棵二进制树。所有输入流的串联在根部。单独的输入流在叶子上。下面给出了一些树的例子，最多有四个输入流a、b、c和d。

对于两个流a和b，树看起来像：

对于三个流a、b和c，树看起来像：

对于四个流a、b、c和d，树看起来像：

每增加一个输入流就增加一层树的深度和一层指示，以达到所有其他的流。

注意： Stream.concat()方法返回的元素是有序的。例如，下面两行返回相同的结果。

Stream.concat(Stream.concat(stream1, stream2), stream3);Stream.concat(stream1, Stream.concat(stream2, stream3));

但下面两个人的结果是不同的。

Stream.concat(Stream.concat(stream1, stream2), stream3); Stream.concat(Stream.concat(stream2, stream1), stream3);

下面是一些例子，以便更好地理解函数的实现。
例1 :

// Implementation of Stream.concat()// method in Java 8 with 2 Streamsimport java.util.*;import java.util.stream.IntStream;import java.util.stream.Stream;  class GFG {      // Driver code    public static void main(String[] args)    {        // Creating two Streams        Stream<String> stream1 = Stream.of("Geeks", "for");        Stream<String> stream2 = Stream.of("GeeksQuiz", "GeeksforGeeks");          // concatenating both the Streams        // with Stream.concat() function        // and displaying the result        Stream.concat(stream1, stream2)            .forEach(element -> System.out.println(element));    }}

输出:

GeeksforGeeksQuizGeeksforGeeks

例2 :

// Implementation of Stream.concat()// method in Java 8 with more than// two Streamsimport java.util.*;import java.util.stream.IntStream;import java.util.stream.Stream;  class GFG {      // Driver code    public static void main(String[] args)    {          // Creating more than two Streams        Stream<String> stream1 = Stream.of("Geeks");        Stream<String> stream2 = Stream.of("GeeksQuiz");        Stream<String> stream3 = Stream.of("GeeksforGeeks");        Stream<String> stream4 = Stream.of("GFG");          // concatenating all the Streams        // with Stream.concat() function        // and displaying the result        Stream.concat(Stream.concat(Stream.concat(stream1,                             stream2), stream3), stream4)            .forEach(element -> System.out.println(element));    }}

输出:

GeeksGeeksQuizGeeksforGeeksGFG

例3 :

// Implementation of Stream.concat()// method in Java 8 with DoubleStreamimport java.util.*;import java.util.stream.Stream;import java.util.stream.DoubleStream;  class GFG {      // Driver code    public static void main(String[] args)    {          // Creating two Streams        DoubleStream Stream1 = DoubleStream.of(1520, 1620);        DoubleStream Stream2 = DoubleStream.of(1720, 1820);          // concatenating both the Streams and        // displaying the result        DoubleStream.concat(Stream1, Stream2)            .forEach(element -> System.out.println(element));    }}

输出:

1520.01620.01720.01820.0

例4 :

// Implementation of Stream.concat()// method in Java 8 and removing// the duplicatesimport java.util.*;import java.util.stream.IntStream;import java.util.stream.Stream;  class GFG {      // Driver code    public static void main(String[] args)    {          // Creating two Streams        Stream<String> stream1 = Stream.of("Geeks", "for", "GeeksforGeeks");        Stream<String> stream2 = Stream.of("GeeksQuiz", "GeeksforGeeks", "for");          // concatenating both the Streams        // with Stream.concat() function        // and displaying the result after        // removing the duplicates        Stream.concat(stream1, stream2).distinct().forEach(element -> System.out.println(element));    }}

输出:

GeeksforGeeksforGeeksGeeksQuiz

例5 :

// Implementation of Stream.concat()// method in Java 8 with LongStreamimport java.util.*;import java.util.stream.Stream;import java.util.stream.LongStream;  class GFG {      // Driver code    public static void main(String[] args)    {          // Creating two Streams        LongStream Stream1 = LongStream.of(1520, 1620);        LongStream Stream2 = LongStream.of(1720, 1820);          // concatenating both the Streams and        // displaying the result        LongStream.concat(Stream1, Stream2)            .forEach(element -> System.out.println(element));    }}

输出: