In Java 8, we can use .toArray() to convert a Stream into an Array.
1. Stream -> String[]
StreamString.java
package com.favtuts.java8.stream;
import java.util.Arrays;
public class StreamConvertToArray {
public static void main(String[] args) {
streamToStringArray();
}
static void streamToStringArray() {
String lines = "I Love Java 8 Stream!";
// split by space, uppercase, and convert to Array
String[] result = Arrays.stream(lines.split("\\s+"))
.map(String::toUpperCase)
.toArray(String[]::new);
for (String s : result) {
System.out.println(s);
}
}
}
Output
I
LOVE
JAVA
8
STREAM!2. IntStream -> Integer[] or int[]
2.1 Stream to Integer[]
StreamInt1.java
package com.favtuts.java8.stream;
import java.util.Arrays;
public class StreamConvertToArray {
public static void main(String[] args) {
streamToIntergerArray();
}
static void streamToIntergerArray() {
int[] num = {1, 2, 3, 4, 5};
Integer[] result = Arrays.stream(num)
.map(x -> x * 2)
.boxed()
.toArray(Integer[]::new);
System.out.println(Arrays.asList(result));
}
}
Output
[2, 4, 6, 8, 10]2.2 Stream to int[]
StreamInt2.java
package com.favtuts.java8.stream;
import java.util.Arrays;
import java.util.stream.IntStream;
import java.util.stream.Stream;
public class StreamConvertToArray {
public static void main(String[] args) {
streamToIntArray();
}
static void streamToIntArray() {
// IntStream -> int[]
int[] stream1 = IntStream.rangeClosed(1, 5).toArray();
System.out.println(Arrays.toString(stream1));
// Stream<Integer> -> int[]
Stream<Integer> stream2 = Stream.of(1, 2, 3, 4, 5);
int[] result = stream2.mapToInt(x -> x).toArray();
System.out.println(Arrays.toString(result));
}
}
Output
[1, 2, 3, 4, 5]
[1, 2, 3, 4, 5]