HashMap in JAVA

Data Structures/Hash Map/hashmap.cpp

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+#include <iostream> 
+#include <iterator> 
+#include <map> 
+
+using namespace std; 
+
+int main() 
+{ 
+
+    // empty map container 
+    map<int, int> gquiz1; 
+
+    // insert elements in random order 
+    gquiz1.insert(pair<int, int>(1, 40)); 
+    gquiz1.insert(pair<int, int>(2, 30)); 
+    gquiz1.insert(pair<int, int>(3, 60)); 
+    gquiz1.insert(pair<int, int>(4, 20)); 
+    gquiz1.insert(pair<int, int>(5, 50)); 
+    gquiz1.insert(pair<int, int>(6, 50)); 
+    gquiz1.insert(pair<int, int>(7, 10)); 
+
+    // printing map gquiz1 
+    map<int, int>::iterator itr; 
+    cout << "\nThe map gquiz1 is : \n"; 
+    cout << "\tKEY\tELEMENT\n"; 
+    for (itr = gquiz1.begin(); itr != gquiz1.end(); ++itr) { 
+        cout << '\t' << itr->first 
+             << '\t' << itr->second << '\n'; 
+    } 
+    cout << endl; 
+
+    // assigning the elements from gquiz1 to gquiz2 
+    map<int, int> gquiz2(gquiz1.begin(), gquiz1.end()); 
+
+    // print all elements of the map gquiz2 
+    cout << "\nThe map gquiz2 after"
+         << " assign from gquiz1 is : \n"; 
+    cout << "\tKEY\tELEMENT\n"; 
+    for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { 
+        cout << '\t' << itr->first 
+             << '\t' << itr->second << '\n'; 
+    } 
+    cout << endl; 
+
+    // remove all elements up to 
+    // element with key=3 in gquiz2 
+    cout << "\ngquiz2 after removal of"
+            " elements less than key=3 : \n"; 
+    cout << "\tKEY\tELEMENT\n"; 
+    gquiz2.erase(gquiz2.begin(), gquiz2.find(3)); 
+    for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { 
+        cout << '\t' << itr->first 
+             << '\t' << itr->second << '\n'; 
+    } 
+
+    // remove all elements with key = 4 
+    int num; 
+    num = gquiz2.erase(4); 
+    cout << "\ngquiz2.erase(4) : "; 
+    cout << num << " removed \n"; 
+    cout << "\tKEY\tELEMENT\n"; 
+    for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { 
+        cout << '\t' << itr->first 
+             << '\t' << itr->second << '\n'; 
+    } 
+
+    cout << endl; 
+
+    // lower bound and upper bound for map gquiz1 key = 5 
+    cout << "gquiz1.lower_bound(5) : "
+         << "\tKEY = "; 
+    cout << gquiz1.lower_bound(5)->first << '\t'; 
+    cout << "\tELEMENT = "
+         << gquiz1.lower_bound(5)->second << endl; 
+    cout << "gquiz1.upper_bound(5) : "
+         << "\tKEY = "; 
+    cout << gquiz1.upper_bound(5)->first << '\t'; 
+    cout << "\tELEMENT = "
+         << gquiz1.upper_bound(5)->second << endl; 
+
+    return 0; 
+} 

Data Structures/Hash Map/hashmap.java

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+// Java program to illustrate 
+// Java.util.HashMap 
+
+import java.util.HashMap; 
+import java.util.Map; 
+
+public class GFG { 
+	public static void main(String[] args) 
+	{ 
+
+		HashMap<String, Integer> map 
+			= new HashMap<>(); 
+
+		print(map); 
+		map.put("vishal", 10); 
+		map.put("sachin", 30); 
+		map.put("vaibhav", 20); 
+
+		System.out.println("Size of map is:- "
+						+ map.size()); 
+
+		print(map); 
+		if (map.containsKey("vishal")) { 
+			Integer a = map.get("vishal"); 
+			System.out.println("value for key"
+							+ " \"vishal\" is:- "
+							+ a); 
+		} 
+
+		map.clear(); 
+		print(map); 
+	} 
+
+	public static void print(Map<String, Integer> map) 
+	{ 
+		if (map.isEmpty()) { 
+			System.out.println("map is empty"); 
+		} 
+
+		else { 
+			System.out.println(map); 
+		} 
+	} 
+}