Java 8 Stream (JNNC Technologies)

Java 8 Stream example to join arrays.

JoinArray.java

package com.mkyong.example.array;

import java.util.Arrays;

import java.util.stream.IntStream;
import java.util.stream.Stream;

public class JoinArray {

    public static void main(String[] args) {

        String[] s1 = new String[]{"a", "b", "c"};
        String[] s2 = new String[]{"d", "e", "f"};
        String[] s3 = new String[]{"g", "h", "i"};

  //join object type array
        String[] result = Stream.of(s1, s2, s3).flatMap(Stream::of).toArray(String[]::new);
        System.out.println(Arrays.toString(result));

        int [] int1 = new int[]{1,2,3};
        int[] int2 = new int[]{4,5,6};
        int[] int3 = new int[]{7,8,9};

  //join 2 primitive type array
        int[] result2 = IntStream.concat(Arrays.stream(int1), Arrays.stream(int2)).toArray();

  //join 3 primitive type array, any better idea?
        int[] result3 = IntStream.concat(Arrays.stream(int1),
   IntStream.concat(Arrays.stream(int2), Arrays.stream(int3))).toArray();

        System.out.println(Arrays.toString(result2));

        System.out.println(Arrays.toString(result3));

    }

}

Output

[a, b, c, d, e, f, g, h, i]
[1, 2, 3, 4, 5, 6]
[1, 2, 3, 4, 5, 6, 7, 8, 9]