Doubt when picking map value

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Doubt when picking map value

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#1 by (4 votes)

4

Hello. When I print the values and keys of Map , it comes from the bottom up. I wanted to know how I can get it from top to bottom.

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

public class ClassDebug {
    public static void main(String a[]){
        Map<String, Integer> map = new HashMap<String, Integer>();
        map.put("Alemanha", 7);
        map.put("Brasil ", 1);
        for(Entry<String, Integer> entry: map.entrySet()) {
            System.out.println(entry.getKey());
        }
           // Imprime: Brasil
           // Imprime: Alemanha

         // Eu quero que imprima:

        // Alemanha e Brasil :V
    }
}

java

asked by anonymous 10.01.2017 / 14:03

1 answer

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score 4 · Accepted Answer

HashMap gives no guarantee as to the order of the elements. The elements there may end up being removed in any order.

However, if you use LinkedHashMap instead of Map :

Map<String, Integer> map = new LinkedHashMap<>();

This will get them sorted by insertion order.

Another way is to get them sorted alphabetically. Use TreeMap in this case:

Map<String, Integer> map = new TreeMap<>();

You can customize the order of the elements also by using constructor of TreeMap that receives Comparator .