Java Collection How to - Convert HashMap to TreeMap to sort key-value pair by keys

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Question

We would like to know how to convert HashMap to TreeMap to sort key-value pair by keys.

Answer

/*from   w  w  w .j  a  v a2  s. com*/
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class Main {

  public static void main(String[] a) {
    Map<String, String> yourMap = new HashMap<String, String>();
    yourMap.put("1", "one");
    yourMap.put("2", "two");
    yourMap.put("3", "three");

    Map<String, String> sortedMap = new TreeMap<String, String>(yourMap);

    System.out.println(sortedMap);
  }
}

The code above generates the following result.

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