使用 forEach 循环在Java中展平 Map 流
给定Java中的 Map 流,任务是使用 forEach() 方法展平流。
例子:
Input: map = {1=[1, 2], 2=[3, 4, 5, 6], 3=[7, 8, 9]}
Output: [1, 2, 3, 4, 5, 6, 7, 8, 9]
Input: map = {1=[G, e, e, k, s], 2=[F, o, r], 3=[G, e, e, k, s]}
Output: [G, e, e, k, s, F, o, r]
方法:
- 让地图变平。
- 创建一个空列表来收集展平的元素。
- 在 forEach 循环的帮助下,将 Map 值的每个元素转换为流并将其添加到列表中
- 此列表是所需的展平地图。
下面是上述方法的实现:
示例 1:使用整数列表。
// Java program to flatten a stream of map
// using forEach() method
import java.util.*;
import java.util.stream.*;
class GFG {
// Function to flatten a Stream of Map
public static List flattenStream(Collection > lists)
{
// Create an empty list to collect the stream
List finalList = new ArrayList<>();
// Using forEach loop
// convert each list into stream
// and add the stream into list
for (List list : lists) {
list.stream()
.forEach(finalList::add);
}
// Return the final flattened list
return finalList;
}
public static void main(String[] args)
{
// Get the map to be flattened.
Map > map = new HashMap<>();
map.put(1, Arrays.asList(1, 2));
map.put(2, Arrays.asList(3, 4, 5, 6));
map.put(3, Arrays.asList(7, 8, 9));
// Flatten the Stream
List flatList = flattenStream(map.values());
// Print the flattened list
System.out.println(flatList);
}
}
输出:
[1, 2, 3, 4, 5, 6, 7, 8, 9]
示例 2:使用字符列表。
// Java program to flatten a stream of map
// using forEach() method
import java.util.*;
import java.util.stream.*;
class GFG {
// Function to flatten a Stream of Map
public static List flattenStream(Collection > lists)
{
// Create an empty list to collect the stream
List finalList = new ArrayList<>();
// Using forEach loop
// convert each list into stream
// and add the stream into list
for (List list : lists) {
list.stream()
.forEach(finalList::add);
}
// Return the final flattened list
return finalList;
}
public static void main(String[] args)
{
// Get the map to be flattened.
Map > map = new HashMap<>();
map.put(1, Arrays.asList('G', 'e', 'e', 'k', 's'));
map.put(2, Arrays.asList('F', 'o', 'r'));
map.put(3, Arrays.asList('G', 'e', 'e', 'k', 's'));
// Flatten the Stream
List flatList = flattenStream(map.values());
// Print the flattened list
System.out.println(flatList);
}
}
输出:
[G, e, e, k, s, F, o, r, G, e, e, k, s]