如何拆分奇数，偶数和两个和在使用流的集合 [英] How to Split odd and even numbers and sum of both in collection using Stream

问题描述

如何使用Java-8的Stream方法拆分奇数和偶数以及两者的总和？

  class SplitAndSumOddEven {
 
 public static void main（String [] args）{
 
 //读取输入
 try（Scanner scanner = new Scanner ））{
 //读取需要读取的输入数。 
 int length = scanner.nextInt（）; 
 //填充输入列表
 List< Integer> inputList = new ArrayList<>（）; 
 for（int i = 0; i  inputList.add（scanner.nextInt（））; 
} 
 // TODO ::对输入进行操作并且产生输出作为输出映射
 Map< Boolean，Integer> oddAndEvenSums = inputList.stream（）; \\我想分裂奇怪&甚至从那个数组和两者的和
 //不要修改下面的代码。从列表中打印输出
 System.out.println（oddAndEvenSums）; 
} 
} 
} 
  

解决方案>

您可以使用 Collectors.partitioningBy 这正是你想要的：

  Map< Boolean，Integer> result = inputList.stream（）。collect（
 Collectors.partitioningBy（x  - > x％2 == 0，Collectors.summingInt（Integer :: intValue）））; 
  

生成的地图包含 true 键和 false 键中的奇数的总和。

how can I Split odd and even numbers and sum both in collection using Stream method of java-8 ??

public class SplitAndSumOddEven {

public static void main(String[] args) {

    // Read the input
    try (Scanner scanner = new Scanner(System.in)) {
        // Read the number of inputs needs to read.
        int length = scanner.nextInt();
        // Fillup the list of inputs
        List<Integer> inputList = new ArrayList<>();
        for (int i = 0; i < length; i++) {
            inputList.add(scanner.nextInt());
        }
        // TODO:: operate on inputs and produce output as output map
        Map<Boolean, Integer> oddAndEvenSums = inputList.stream(); \\here I want to split odd & even from that array and sum of both
        // Do not modify below code. Print output from list
        System.out.println(oddAndEvenSums);
    }
}
}

解决方案

You can use Collectors.partitioningBy which does exactly what you want:

Map<Boolean, Integer> result = inputList.stream().collect(
       Collectors.partitioningBy(x -> x%2 == 0, Collectors.summingInt(Integer::intValue)));

The resulting map contains sum of even numbers in true key and sum of odd numbers in false key.

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