Creating constructors with different fields error

Question

I have created a class that takes two LinkedHashMaps as fields. I have tried adding a second constructor that takes a LinkedHashMap with different data types as its fields, however I am getting an error. From what I know, constructors simply need different fields. Why doesn't this work?

public class SpecialMap extends LinkedHashMap<LinkedHashMap<String, String>, LinkedHashMap<String, Integer>> {

    LinkedHashMap<String, String> key = new LinkedHashMap<>();
    LinkedHashMap<String, String> key2 = new LinkedHashMap<>();
    LinkedHashMap<String, Integer> value = new LinkedHashMap<>();
    LinkedHashMap<String, String> value2 = new LinkedHashMap<>();

    public SpecialMap(LinkedHashMap<String, String> _key, LinkedHashMap<String, Integer> _value) {
        this.key = _key;
        this.value = _value;
    }

    public SpecialMap(LinkedHashMap<String, String> _key, LinkedHashMap<String, String> val) {
        this.key2 = _key;
        this.value2 = val;
    }

}