JGRASP Won't Allow To Declare Variables As Strings

Java Code:

import java.util.Scanner;//Imports Scanner
public class operadoreslogicos//imports a public class {
public static void main (String [] args)//defines the state of a class {
Scanner input = new Scanner (System.in);//Inputs a scanner to read user
//keyboard
boolean cierto = true,// Declares variables as boolean and applies a value

[Code] .....

The word string is supposed to turn purple when I type it, but it just stays normal, so it doesn't declare hello and bye as variables.