First Udemy module I took covered basic Java commands.   It discussed primitives and non-primitives.   

Double in Java is what Float is in C#.   Double is 64-bit with 15 decimal places.  Float is 32-bit with 7 decimal places

package com.michael.test;

// class is a page
public class Main {

// public static void is like a paragraph
public static void main(String[] args) {

// Non-Primtitive
System.out.println("This is a test");
Integer number2 = 2;
Double double2 = 2.2;
Boolean boolean2 = false;
Character character = 'D';

// Primitive
int number = 5;
double decimalNumber = 102.5;
boolean trueFalse = true;
char letter = 's';
System.out.println(letter);

printMessage("Test message from other method");
int result = printMessageInt("result");
System.out.println(result);
// sout is the short cut
}

private static void printMessage(String message) {
System.out.println(message);

}

private static int printMessageInt(String message) {
System.out.println(message);
return 12;

}


}
This is a test
s
Test message from other method
result
12