Java 8 stream reduce example

Here is java 8 stream reduce example like sum of integers using reduce() method of stream, Join stream using reduce method of stream.

Example 1: Stream reduce

        java.util.List<Integer> integer = Arrays.asList(1, 2, 15, 10, 5, 5, 10, 3, 4);

        int total = integer.stream().reduce((integer1, integer2) -> {
            return integer1 + integer2;
        }).get();

        System.out.print("Sum of number is : " + total);

 Output:

Sum of number is : 55

 Example 2: Stream reduce with seed value

java.util.List<Integer> integer = Arrays.asList(1, 2, 15, 10, 5, 5, 10, 3, 4);
       int total = integer.stream().reduce(0, (sum, i) -> {
           sum = sum + i;
           return sum;
       });
       System.out.print("Sum of number is : " + total);

 output:

Sum of number is : 55

Example 3: Join List of String

java.util.List<String> strings = Arrays.asList("Zohne", "Redy", "Zohne", "Redy", "Stome");
       String joinString = strings.stream().reduce((string1, string2) -> {
           return string1 + ", " + string2;
       }).get();
       System.out.println("Join String using reduce: "+joinString);

 Output:

Join String using reduce: Zohne, Redy, Zohne, Redy, Stome

References:

https://docs.oracle.com/javase/tutorial/collections/streams/reduction.html