Java Collection: Map Interface

A Map contains values on the basis of keys. Each key and value pair is known as an entry. It contains only unique keys. But it can contain duplicate values.

Note that a Map can't be traversed so you need to convert it into Set using keySet() or entrySet() method.

Source code of Item.java

package com.t4b.test; public class Item { String name; int id; double price; public Item(String name, int id, double price) { super(); this.name = name; this.id = id; this.price = price; } @Override public String toString() { return "Item [name=" + name + ", id=" + id + ", price=" + price + "]"; } }

Source code of TestMain.java

package com.t4b.test; import java.util.HashMap; import java.util.Map; public class TestMain { public static void main(String[] args) { Map<Integer, Item> map = new HashMap<Integer, Item>(); map.put(1, new Item("Apple", 1, 150.0)); map.put(2, new Item("Grape", 2, 250.0)); map.put(3, new Item("Mango", 3, 10)); map.put(2, new Item("Pine Apple", 4, 100)); for (Map.Entry<Integer, Item> item : map.entrySet()) { System.out.println(item.getKey() + " : " + item.getValue()); } map.remove(2); map.replace(1, new Item("Apple", 1, 220.0)); for (Map.Entry<Integer, Item> item : map.entrySet()) { System.out.println(item.getKey() + " : " + item.getValue()); } } }

Happy Exploring!