Java Equivalent to Python Dictionaries

Java Equivalent to Python Dictionaries

Pythons dict class is an implementation of what the Python documentation informally calls mapping types. Internally, dict is implemented using a hashtable.

Javas HashMap class is an implementation of the Map interface. Internally, HashMap is implemented using a hashtable.

There are a few minor differences in syntax, and I believe the implementations are tuned slightly differently, but overall they are completely interchangeable.

The idea of dictionary and Map is similar. Both contain elements like

key1:value1, key2:value2 ... and so on

In Java, Map is implemented different ways like HashMap, or TreeMap etc. put(), get() operations are similar

import java.util.HashMap;

Map map = new HashMap();
// Put elements to the map
map.put(Ram, new Double(3434.34));
map.put(Krishna, new Double(123.22));
map.put(Hary, new Double(1378.00));
//to get elements
map.get(Krishna); // =123.22
map.get(Hary); // = 1378.00 

See documentation of HashMap in java8 https://docs.oracle.com/javase/8/docs/api/java/util/HashMap.html

Java Equivalent to Python Dictionaries

One difference between the two is that dict has stricter requirements as to what data types can act as a key. Java will allow any object to work as a key — although you should take care to ensure that the objects hashCode() method returns a unique value that reflects its internal state. Python requires keys to fit its definition of hashable, which specifies that the objects hash code should never change over its lifetime.