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How to sort HashMap by key and by value

Sort HashMap by Key ::
By default hashmap does not maintain order of the elements,so we can not guarantee how the elements will be printed/accessed in hashMap. For maintaining order we can use another data structure called “TreeMap” which implements “SortedMap” interface and sorts the map by key in ascending order.

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Sort HashMap by Value::
To sort Hashmap by value ,we need to pass the entrire map to a list and then call Collections.sort() method to sort the list.Using Compartor class of java.util package we can override compare(object1,object2) to sort the values.
compare() method returns 1 if valueof firts object is greater than second and -1 if value of first object is less than value of second object and it returns 0 if values of first and second object are equal.

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