用 Java 将地图转换成流的程序
原文:https://www . geesforgeks . org/program-to-convert-a-map-a-stream-in-Java/
一个流是一个支持各种方法的对象序列，这些方法可以被流水线化以产生期望的结果。
以下是用 Java 将地图转换为流各种方法:
-
Converting complete Map into Stream: This can be done with the help of Map.entrySet() method which returns a Set view of the mappings contained in this map. In Java 8, this returned set can be easily converted into a Stream of key-value pairs using Set.stream() method.
算法:
- 获取地图。
- 使用 Map.entrySet()方法将地图转换为集合。
- 使用 Set.stream()将获得的集合转换为流
- 返回/打印地图流。
程序:
```java // Java Program to convert // Map into Stream
import java.util.; import java.util.stream.;
class GFG {
// Generic function to convert List of // String to List of Integer public static Stream > convertMapToStream(Map map) {
// Return the obtained Stream return map
// Convert the Map to Set .entrySet()
// Convert the Set to Stream .stream(); }
public static void main(String args[]) {
// Create a Map Map map = new HashMap<>();
// Add entries to the Map map.put(1, "Geeks"); map.put(2, "forGeeks"); map.put(3, "A computer Portal");
// Print the Map System.out.println("Map: " + map);
// Convert the Map to Stream Stream > stream = convertMapToStream(map);
// Print the TreeMap System.out.println("Stream: " + Arrays.toString(stream.toArray())); } } ```
Output:
```java Map: {1=Geeks, 2=forGeeks, 3=A computer Portal} Stream: [1=Geeks, 2=forGeeks, 3=A computer Portal]
```
-
Converting only the Keyset of the Map into Stream: This can be done with the help of Map.keySet() method which returns a Set view of the keys contained in this map. In Java 8, this returned set can be easily converted into a Stream of key-value pairs using Set.stream() method.
算法:
- 获取地图。
- 使用 Map.keySet()方法将地图转换为集合。
- 使用 Set.stream()将获得的集合转换为流
- 返回/打印地图流。
程序:
```java // Java Program to convert // Map into Stream
import java.util.; import java.util.stream.;
class GFG {
// Generic function to convert List of // String to List of Integer public static Stream convertMapToStream(Map map) {
// Return the obtained Stream return map
// Convert the Map to Set .keySet()
// Convert the Set to Stream .stream(); }
public static void main(String args[]) {
// Create a Map Map map = new HashMap<>();
// Add entries to the Map map.put(1, "Geeks"); map.put(2, "forGeeks"); map.put(3, "A computer Portal");
// Print the Map System.out.println("Map: " + map);
// Convert the Map to Stream Stream stream = convertMapToStream(map);
// Print the TreeMap System.out.println("Stream: " + Arrays.toString(stream.toArray())); } } ```
Output:
```java Map: {1=Geeks, 2=forGeeks, 3=A computer Portal} Stream: [1, 2, 3]
```
-
Converting only the Value of the Map into Stream: This can be done with the help of Map.values() method which returns a Set view of the values contained in this map. In Java 8, this returned set can be easily converted into a Stream of key-value pairs using Set.stream() method.
算法:
- 获取地图。
- 使用 Map.values()方法将地图转换为集合。
- 使用 Set.stream()将获得的集合转换为流
- 返回/打印地图流。
程序:
```java // Java Program to convert // Map into Stream
import java.util.; import java.util.stream.;
class GFG {
// Generic function to convert List of // String to List of Integer public static Stream convertMapToStream(Map map) {
// Return the obtained Stream return map
// Convert the Map to Set .values()
// Convert the Set to Stream .stream(); }
public static void main(String args[]) {
// Create a Map Map map = new HashMap<>();
// Add entries to the Map map.put(1, "Geeks"); map.put(2, "forGeeks"); map.put(3, "A computer Portal");
// Print the Map System.out.println("Map: " + map);
// Convert the Map to Stream Stream stream = convertMapToStream(map);
// Print the TreeMap System.out.println("Stream: " + Arrays.toString(stream.toArray())); } } ```
Output:
```java Map: {1=Geeks, 2=forGeeks, 3=A computer Portal} Stream: [Geeks, forGeeks, A computer Portal]
```
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