Lesson One: The first programme that does absolutely nothing at all.
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Copy the next code and past it in your text editor. Save it under the
name Main.java (mind the capital M).
//---------------------------------------------
// Class
//---------------------------------------------
public class Main {
//---------------------------------------------
// Methods
//---------------------------------------------
public static void main(String args[]) {
System.out.println("Starting the
calculator...");
}
}
Compile this programme by executing ´javac Main.java´ in your
DOS/UNIX window and execute it in the same window with ´java Main´.
This programme does nothing but display a text string in your
DOS/UNIX window. It seems little, but this piece of code will serve as a
tree trunc to which we can attach everything else.
Reviewing the code:
In a line, text after // is not regarded by the compiler, and this can
be used to comment your code. ´public class Main {´ defines this class.
By convention, names of a class start with a capital. A class is a piece
of java code that can be re-used as a building block somewhere else.
Because this is the starting class, the function main is defined. This
allows the programme to be started by executing ´java Main´ in your
DOS/UNIX window. In the main function, a text string is printed to this
window.
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