Java: Identifier Names with Unicode Characters

Identifier Names with Unicode Characters

function, variable names must be Unicode: Letter Character . (Math symbols NOT allowed (e.g. ⊕°).)

Class name cannot contain unicode letter. e.g. Xλ

Error: Could not find or load main class Xλ
Caused by: java.lang.ClassNotFoundException: Xλ

class Xtt {
    public static void main(String[] arg) {

    String λ = "😸";
    double π = 3.1;

    System.out.println( λ );
    System.out.println( π );
    }
}