How do I convert Map to Array in Java
Learn how to convert Maps into ArrayLists in Java, a useful technique for storing keys, values, and HashMap nodes effectively at rrtutors.com.
Rather than declaring separate variables for each item, you can store multiple values in an array by converting a map to an array. A Map consists of a key and a value pair. Among the list objects, it can contain key values while the other can contain map values separately.
How to convert a Map to Array in Java
Here are the simple steps you need to follow to convert a map to a list:
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Step 1: First, create the Map object.
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Step 2: Input elements into it as key-value pairs by calling the put() method
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Step 3: For the keys of the map, create an ArrayList of integer type. Call keySet() of the Map class in its constructor.
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Step 4: Assign the values of the map to an ArrayList of String type. Call the values() method of the Map class in its constructor.
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Step 5: Lastly, print the results of both lists.
Example
In this example we are going to follow the above steps to convert Map to an Array
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import java.util.ArrayList; import java.util.HashMap; import java.util.Map; public class Convert_Map_to_Array { public static void main(String[] args) { Map<Integer, String> ManMap = new HashMap<>(); ManMap.put(20, "Python"); ManMap.put(30, "Java"); ManMap.put(50, "Ruby"); ManMap.put(60, "Python"); ArrayList<Integer> keyList = new ArrayList<Integer>(ManMap.keySet()); ArrayList<String> valueList = new ArrayList<String>(ManMap.values()); System.out.println("Map content ::"+keyList); System.out.println("Arraylist ::"+valueList); } } |
Output:
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Map content ::[50, 20, 60, 30] Arraylist ::[Ruby, Python, Python, Java] |
Keywords: How to convert a Map to Array in Java , Java Collections, Java