Statement oriented approach against expression oriented one

Question

I was going through this article on java9 and came across this line where it states that Java is statement-oriented whereas REPLs are expression-oriented.

Can somebody explain the difference between these two?

Answer 1

A very quick and coincidently visible difference is that following types of expressions can be made into a statement by terminating the expression with a semicolon (;).

• Assignment expressions
• Any use of ++ or --
• Method invocations
• Object creation expressions
• Such statements are called expression statements.

So when in your HelloWorld.java class the following would not compile -

int z = 1 //(; missing)

Jshell on its prompt successfully stores the value as:

jshell> int z = 1
z ==> 1

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Morevoer

Statements are roughly equivalent to sentences in natural languages. A statement forms a complete unit of execution.

whereas an Expression is a construct made up of variables, operators, and method invocations, which are constructed according to the syntax of the language, that evaluates to a single value.