Prerequisite : JShell in Java 9 We can declare variables and use anywhere throughout Jshell session. Let’s create an integer variable. 
Semicolon (;) is optional, we can leave it and it works fine. See, variable b is created without using semicolon.
Scratch Variables
If we don’t provide variable name, Java create implicit variable to store the value. These variables start with $ sign. We can use these variable by specifying implicit variable, as we did in the following screen-shot.
Expressions
We can test any valid Java expression to get instant output. See, the following example. Adding two integers Compound expression Creating and Calling Methods To test method business logic, create a method and get result immediately. See, the following example
