How to use JShell in Java?

JSHELL is the command line tools for Read/Evaluate/Print/Loop (REPL) Java Statements. It can be used for learning Java Concepts. The Java Statements executed in JSHELL is called as Snippets. To run, type jshell in Terminal/Command Window.

Minimum Java Version?

• Minimum JDK9 version is required to use JSHELL

JSHELL Commands

• /help - Getting help
• /exit - Exit JSHELL
• /list - List ALL Snippets
• /edit - Edit Snippet in Editor
• /save - Save Snippets into File
• /vars - List variables
• /imports - List imported packages
• /reset - Reset the current session
• Ctrl+l - Clear the Screen
• Ctrl+C - To exit from the current snippet

Use as Calculator (Java Operators Demo)

  10 + 20
  100 * 3863

Create a String

  String str = "Hello";
  str.toUpperCase()
  str.length()

Create a List

• Creatigng a Simple List
• Getting Dynamic Help of a Method (Press Tab after typing Char(s))
• List.of() vs Arrays.asList()

  var myList = Arrays.asList(4,5,3,1,2);
  myList.sort(Comparator.naturalOrder())
  myList
  myList.sort(Comparator.reverseOrder())
  myList

Create a Greet Method

• Simple method

  String display(){
    return "Welcome to JSHELL";
  }
  display()
  

• Method with Parameter

  String greetUser(String name){
    return "Welcome " + name;
  }
  greetUser("Anthoniraj")
  

Create a Boolean Method

• If-Else Statement

  boolean isEven(int n){
    if (n % 2 == 0) {
       return true;
    }else{
       return false;
    }
  }
isEven(10)
isEven(9)

• Conditional Operator

  boolean isOdd(int n){ 
   return (n%2 !=0)? true:false; 
  }
  

Save the Snippets into File

/save C:\Users\Anthoniraj\Documents\Snippet.java