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1 Mẹo Hướng dẫn Map Mới Nhất

Mẹo Hướng dẫn Map Mới Nhất

Pro đang tìm kiếm từ khóa Map được Cập Nhật vào lúc : 2022-01-15 12:04:36 . Với phương châm chia sẻ Mẹo Hướng dẫn trong nội dung bài viết một cách Chi Tiết 2022. Nếu sau khi đọc tài liệu vẫn ko hiểu thì hoàn toàn có thể lại Comment ở cuối bài để Mình lý giải và hướng dẫn lại nha.

This Java program shows how to iterate a HashMap that contains arraylists of String.

In the Java program to iterate a HashMap containing ArrayLists there is a method getMap() where 3 lists are created and stored in the HashMap.

First you need to iterate the HashMap, though there are several ways to iterate over a HashMap, but here I have used the for-each loop for iterating the created HashMap. Each Map.Entry object is a key-value pair where value is the ArrayList stored with the given key. That’s the list retrieved using listEntry.getValue() method.

In the second for-each loop List that is retrieved using listEntry.getValue() is iterated and the elements that are in the list are displayed.

Java Program to Iterate HashMap of ArrayLists

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MapLoop
public static void main(String[] args)
MapLoop mapLoop = new MapLoop();
Map<String, List> cityMap = mapLoop.getMap();
int i = 0;
// iterating over a map
for(Map.Entry<String, List> listEntry : cityMap.entrySet())
System.out.println(“Iterating list number – ” + ++i);
// iterating over a list
for(String cityName : listEntry.getValue())
System.out.println(“City – ” + cityName);

/**
* A method to create a list and store it in a Map
* @return
*/
private Map<String, List> getMap()
Map<String, List> cityMap = new HashMap<String, List>();
// First List
List temp = new ArrayList();
temp.add(“Delhi”);
temp.add(“Mumbai”);
// Putting first list in the map
cityMap.put(“1”, temp);
// Second List
temp = new ArrayList();
temp.add(“Hyderabad”);
temp.add(“Bangalore”);
// Putting second list in the map
cityMap.put(“2”, temp);
// Third List
temp = new ArrayList();
temp.add(“Kolkata”);
temp.add(“Chennai”);
// Putting third list in the map
cityMap.put(“3”, temp);
return cityMap;

OutputIterating list number – 1
City – Delhi
City – Mumbai
Iterating list number – 2
City – Hyderabad
City – Bangalore
Iterating list number – 3
City – Kolkata
City – Chennai

That’s all for this topic How to iterate a Hash map of arraylists of String in Java. If you have any doubt or any suggestions to make please drop a comment. Thanks!

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