public static void main(String[] args )
The Java compiler would accept the line. But it looks sloppy to human eyes.
println()
public class Hello
{
public static void main ( String[] args )
{
System.out.println("Hello World!");
}
}
There are rules about where spaces may be used, and optional style rules about how to make a program look nice. Rather than look at a list of rules, look at some Java programs and pick up the rules by example.
The main method of this program consists of a single statement:
System.out.println("Hello World!");
This statement writes the characters inside the quotation marks on one line. (The quotation marks are not written.)
A statement in a programming language is a command for the computer to do something. It is like a sentence of the language. A statement in Java is followed by a semicolon.
Methods are built out of statements.
The statements in a method are placed between
braces { and } as in
this example.
Programs usually contain many methods. Our example program contains just one method.
The part "Hello World!" is called a string literal.
A string is a sequence of characters.
A string literal consists of characters between quote marks, but does not include the quote marks.
It can contain any valid character, including white space and punctuation.
This program writes a string to the monitor and then stops.
In a source file, a string literal must be on just one line. The following is not legal, and will not compile:
System.out.println("Hello
World!");
(Review: ) Say that the file Hello.java contains the example program. In order to run it, what two things must be done?