LinkedHashMap in Java

The LinkedHashMap is HashMap with an additional feature that the elements can be accessed in their insertion order. 
<b>Important Features:</b>
* A LinkedHashMap contains values based on the key. It implements the Map interface and extends the HashMap class.
* It contains only unique elements.
* It may have one null key and multiple null values.
* It is non-synchronized.
* It is the same as HashMap with an additional feature that it maintains insertion order. 
```
import java.util.*;

public class Main {
    public static void main(String a[]) {
        LinkedHashMap<String, String> lhm = new LinkedHashMap<>();

        lhm.put("one", "1");
        System.out.println(lhm);
    }
}
```
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