21 lines
606 B
Java
21 lines
606 B
Java
package stream;
|
|
|
|
import java.util.Arrays;
|
|
import java.util.List;
|
|
import java.util.Optional;
|
|
|
|
public class StreamExample06 {
|
|
public static void main(String[] args) {
|
|
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
|
|
|
|
// 使用 reduce 求和
|
|
Optional<Integer> sum = numbers.stream()
|
|
.reduce(Integer::sum);
|
|
sum.ifPresent(System.out::println); // 输出: 15
|
|
|
|
// 使用带初始值的 reduce
|
|
int sumWithIdentity = numbers.stream()
|
|
.reduce(0, Integer::sum);
|
|
System.out.println(sumWithIdentity); // 输出: 15
|
|
}
|
|
} |