How can we implement a map in JShell in Java 9?

JavaObject Oriented ProgrammingProgramming

JShell is a java shell tool that has introduced in Java 9. It is an interactive tool that reads input, executes it, and prints it in the command-line prompt. We don't need to write a main() method to execute it like Java class.

We can implement different collections includes set, list, and map in the JShell tool. The important collection is the Map interface, and it is a key-value pair. A Map doesn't contain duplicate keys and each key maps to at most one value.

In the below example, we can able to implement the non-empty map.

| Welcome to JShell -- Version 9.0.4
| For an introduction type: /help intro

jshell> Map<String, String> map = new HashMap<String, String>();
map ==> {}

jshell> map.put("raja", "ramesh");
$2 ==> null

jshell> map.put("adithya", "sai");
$3 ==> null

jshell> map.put("jai", "dev");
$4 ==> null

jshell> map.put("chaintaya", "krishna");
$5 ==> null

jshell> Map<String, String> immutableMap = Collections.unmodifiableMap(map);
immutableMap ==> {raja=ramesh, jai=dev, chaintaya=krishna, adithya=sai}

Updated on 20-Mar-2020 08:09:49