void
clear()
Removes
all of the mappings from this map.
import java.util.*; class HashMapClear{ public static void main(String args[]){ Map<Integer, String> myMap1 = new HashMap<> (); /* Add data to the myMap1 */ myMap1.put(1, "First"); myMap1.put(2, "Second"); myMap1.put(3, "Third"); myMap1.put(4, "Fourth"); System.out.println("Data in myMap1 is"); System.out.println(myMap1); System.out.println("\nCalling clear method on map"); myMap1.clear(); System.out.println("\nData in myMap1 is"); System.out.println(myMap1); } }
Output
Data in myMap1 is {1=First, 2=Second, 3=Third, 4=Fourth} Calling clear method on map Data in myMap1 is {}
1. Implement
the clear functionality for the HashMap
import java.util.*; class HashMapClearEx{ static void clearMap(Map myMap1){ Set<Integer> mySet = myMap1.keySet(); int size = myMap1.size(); Object keys[] = new Object[size]; int i=0; Iterator iter1 = mySet.iterator(); while(iter1.hasNext()){ keys[i] = iter1.next(); i++; } for(i=0; i < size; i++) myMap1.remove(keys[i]); } public static void main(String args[]){ Map<Integer, String> myMap1 = new HashMap<> (); /* Add data to the myMap1 */ myMap1.put(1, "First"); myMap1.put(2, "Second"); myMap1.put(3, "Third"); myMap1.put(4, "Fourth"); System.out.println("Data in myMap1 is"); System.out.println(myMap1); System.out.println("\nCalling clear method on map"); clearMap(myMap1); System.out.println("\nData in myMap1 is"); System.out.println(myMap1); } }
Output
Data in myMap1 is {1=First, 2=Second, 3=Third, 4=Fourth} Calling clear method on map Data in myMap1 is {}
Method
“clearMap” gets all the keys of the given Map using iterator and
removes each key, value mapping from the Map.
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