'Sort a Map in descending order based on value of arraylist in Java

I have a Map of type

static Map<String, ArrayList<String>> Container = new HashMap<String, ArrayList<String>>();

The value array list has two elements, the first index is an extension and the second is size,

Container : {
C:\HTML\viewer\files\output\ViewerJS\commons-io-2.11.0-src (2).zip=[zip, 919362], 
C:\HTML\viewer\files\jar_files (2).zip=[zip, 345068], 
C:\HTML\viewer\files\output\ViewerJS\rar1.rar=[rar, 1], 
C:\HTML\viewer\files\output\files.zip=[zip, 10184010], 
C:\HTML\viewer\files\check2.zip=[zip, 1]
}

I want the map to be sorted in descending order based on the number in index 1 of the map value which is the size which is also of type STRING.

A little help would be much appreciated, Thank you.

javasortingarraylisthashmap


Solution 1:[1]

This uses a TreeMap and a utility function(addElementsToMap) that would update your map.

Note: A Comparator is provided at map creation time.

public class DriverClass {


private static Map<Integer, ArrayList<String>> container = new TreeMap<>((o1, o2) -> (o2 < o1) ? -1 : 1);

public static void main(String[] args) {
    DriverClass driver = new DriverClass();
    String[] elementsList = driver.collectElements();
    driver.addElementsToMap(elementsList);
    container.entrySet().forEach(e -> System.out.println(e.getKey() + " ----- " + e.getValue()));

}

private void addElementsToMap(String[] elementsList) {
     int i = 0;
    for (int j = elementsList.length/2; j <= elementsList.length-1; j++) {
       int size = Integer.parseInt(elementsList[i+1].replaceAll("]", ""));
        container.put(size, new ArrayList<>(Arrays.asList(elementsList[i], elementsList[i+1])));
        i += 2;
    }
}

private String[] collectElements() {
    return new String[] {
        "C:\\HTML\\viewer\\files\\output\\ViewerJS\\commons-io-2.11.0-src (2).zip=[zip", "919362]",
        "C:\\HTML\\viewer\\files\\jar_files (2).zip=[zip", "345068]",
        " C:\\HTML\\viewer\\files\\output\\ViewerJS\\rar1.rar=[rar", "1]",
        "C:\\HTML\\viewer\\files\\output\\files.zip=[zip", "10184010]",
        "C:\\HTML\\viewer\\files\\check2.zip=[zip", "1]"};
 }
}

outputs:

10184010 ----- [C:\HTML\viewer\files\output\files.zip=[zip, 10184010]]
919362 ----- [C:\HTML\viewer\files\output\ViewerJS\commons-io-2.11.0-src (2).zip=[zip, 919362]]
345068 ----- [C:\HTML\viewer\files\jar_files (2).zip=[zip, 345068]]
1 ----- [C:\HTML\viewer\files\check2.zip=[zip, 1]]
1 ----- [ C:\HTML\viewer\files\output\ViewerJS\rar1.rar=[rar, 1]]

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1

Related Questions