Simple Java Stream and Lambda examples for my sister

StreamExamples.java

import java.util.Arrays;
import java.util.function.IntUnaryOperator;
import java.util.stream.IntStream;

public class StreamExamples {

    public static void main(String[] args) {
        int[] myData = new int[]{1, 1, 2, 3, 5, 8, 13, 21, 34};
        System.out.println("myData: " + Arrays.toString(myData));

        System.out.println("Odd only: " + Arrays.toString(oddOnly(myData)));
        System.out.println("Multiplied by 2: " + Arrays.toString(multiply(myData, 2)));
        System.out.println("Sum: " + sum(myData));

        IntUnaryOperator squareOp = i -> i * i;
        System.out.println("Squared: " + Arrays.toString(doUnaryOperation(myData, squareOp)));

        int[] myOtherData = new int[]{1, 2, 4, 8, 16, 32, 64, 128, 256};
        System.out.println("myOtherData: " + Arrays.toString(myOtherData));
        System.out.println("Combined with myData: " + Arrays.toString(combine(myData, myOtherData)));

    }

    private static int[] oddOnly(int[] data) {
        return Arrays.stream(data)          // convert array to stream
                .filter(i -> i % 2 != 0)    // filter for all odd elements
                .toArray();                 // convert back to array
    }

    private static int[] multiply(int[] data, int multiple) {
        return Arrays.stream(data)
                .map(i -> i * multiple)
                .toArray();
    }

    private static int[] combine(int[] data1, int[] data2) {
        assert data1.length == data2.length;
        return IntStream.range(0, data1.length)
                .map(i -> data1[i] + data2[i])
                .toArray();
    }

    private static int sum(int[] data) {
        return Arrays.stream(data).sum();
    }

    private static int[] doUnaryOperation(int[] data, IntUnaryOperator op) {
        return Arrays.stream(data)
                .map(op)
                .toArray();
    }
}