your first cup of java (for win32).mht

Your First Cup of Java

                    <P><FONT size=3D-1>So, you've heard that with the =
Java=20
                    programming language, you can "write once, run =
anywhere."=20
                    This means that when you compile your program, you =
don't=20
                    generate instructions for one specific platform. =
Instead,=20
                    you generate Java bytecodes, which are instructions =
for the=20
                    Java Virtual Machine (Java VM). If your =
platform--whether=20
                    it's Windows, UNIX, MacOS, or an Internet =
browser--has the=20
                    Java VM, it can understand those=20
                bytecodes.</FONT></P></TD></TR></TBODY></TABLE></TD>
            <TD vAlign=3Dtop rowSpan=3D2>&nbsp;</TD></TR>
          <TR>
            <TD vAlign=3Dtop>Your first program, =
<CODE>HelloWorldApp</CODE>,=20
              will simply display the greeting "Hello world!". To create =
this=20
              program, you will:&nbsp;=20
              <UL>
                <LI><B>Create a <FONT color=3D#990099>source =
file</FONT>.</B> A=20
                source file contains text, written in the Java =
programming=20
                language, that you and other programmers can understand. =
You can=20
                use any text editor to create and edit source files. =
<BR>&nbsp;=20
                <LI><B>Compile the source file into a <FONT=20
                color=3D#990099>bytecode file</FONT>.</B> The =
<I>compiler</I>,=20
                <CODE>javac</CODE>, takes your source file and =
translates its=20
                text into instructions that the <I>Java Virtual Machine=20
                </I>(Java VM) can understand. The compiler converts =
these=20
                instructions into a bytecode file. <BR>&nbsp;=20
                <LI><B>Run the program contained in the bytecode =
file.</B> The=20
                Java interpreter installed on your computer implements =
the Java=20
                VM. This interpreter takes your bytecode file and =
carries out=20
                the instructions by translating them into instructions =
that your=20
                computer can understand. </LI></UL>
              <P>
              <CENTER><IMG height=3D218 alt=3D""=20
              =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/helloWo=
rld.gif"=20
              width=3D465 align=3Dbottom NATURALSIZEFLAG=3D"3"></CENTER>
              <P></P></TD></TR></TBODY></TABLE>
        <P><IMG height=3D16 alt=3D""=20
        =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/arrow.g=
if"=20
        width=3D13><FONT size=3D-1><A=20
        =
href=3D"http://java.sun.com/docs/books/tutorial/getStarted/cupojava/win32=
.html#top">top</A></FONT>=20
        <BR>
        <HR align=3Dleft width=3D"70%">
        <A name=3D2a></A>
        <H2><FONT face=3D"Arial, Helvetica, sans-serif" =
color=3Dred>a.</FONT> <FONT=20
        face=3D"Arial, Helvetica, sans-serif">Create a Source =
File.</FONT>=20
        </H2></FONT>
        <BLOCKQUOTE>To create a source file, you have two options:=20
          <UL>
            <LI>You can save the file <CODE><A=20
            =
href=3D"http://java.sun.com/docs/books/tutorial/getStarted/application/ex=
ample/HelloWorldApp.java"=20
            target=3Dsource><FONT=20
            color=3D#bb000f><CODE>HelloWorldApp.java</CODE></FONT></A><A =

            =
href=3D"http://java.sun.com/docs/books/tutorial/getStarted/application/ex=
ample/HelloWorldApp.java"><IMG=20
            height=3D11 alt=3D"(in a .java source file)"=20
            =
src=3D"http://java.sun.com/docs/books/tutorial/images/sourceIcon.gif"=20
            width=3D11 align=3DabsMiddle border=3D0></A></CODE> on your =
computer and=20
            avoid a lot of typing. Then, you can go straight to <A=20
            =
href=3D"http://java.sun.com/docs/books/tutorial/getStarted/cupojava/win32=
.html#2b">step=20
            b</A>.<BR><BR>
            <LI>Or, you can follow these longer instructions: </LI></UL>
          <P><B><FONT color=3D#ff0000>1.</FONT></B> Start NotePad. In a =
new=20
          document, type in the following code:</P>
          <TABLE cellSpacing=3D2 cellPadding=3D2 width=3D500 border=3D1>
            <TBODY>
            <TR>
              <TD width=3D"100%"><PRE>/**
 * The HelloWorldApp class implements an application that
 * displays "Hello World!" to the standard output.
 */
public class HelloWorldApp {
    public static void main(String[] args) {
        // Display "Hello World!"
        System.out.println("Hello World!");
    }
}
</PRE></TD></TR></TBODY></TABLE>
          <BLOCKQUOTE>&nbsp;=20
            <TABLE cellSpacing=3D0 cellPadding=3D10 width=3D450 =
border=3D1>
              <TBODY>
              <TR bgColor=3D#ffffcc>
                <TD bgColor=3D#ffffdb>
                  <TABLE cellSpacing=3D0 cellPadding=3D0 width=3D402 =
border=3D0>
                    <TBODY>
                    <TR>
                      <TD width=3D"77%">&nbsp;<B><FONT=20
                        face=3D"Arial, Helvetica, sans-serif"><FONT=20
                        color=3D#990000>Be Careful When You=20
                      Type</FONT></FONT></B></TD>
                      <TD width=3D"13%"><IMG height=3D30 alt=3D""=20
                        =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/typeA.g=
if"=20
                        width=3D30></TD>
                      <TD width=3D"10%"><IMG height=3D30 alt=3D""=20
                        =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/typea2.=
gif"=20
                        width=3D30></TD></TR></TBODY></TABLE>
                  <P><FONT size=3D-1>Type all code, commands, and file =
names=20
                  exactly as shown. The Java compiler and interpreter =
are=20
                  <I>case-sensitive</I>, so you must capitalize=20
                  consistently.</FONT></P>
                  <CENTER>
                  <P><CODE>HelloWorldApp <IMG height=3D19 alt=3D""=20
                  =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/notequa=
l.gif"=20
                  =
width=3D20>&nbsp;helloworldapp</CODE></CENTER></P></TD></TR></TBODY></TAB=
LE></BLOCKQUOTE><B><FONT=20
          color=3D#ff0000>2.</FONT> </B>Save this code to a file. From =
the menu=20
          bar, select <FONT color=3D#990099>File</FONT> &gt; <FONT=20
          color=3D#990099>Save As</FONT>. In the <FONT =
color=3D#990099>Save=20
          As</FONT> dialog box:&nbsp;</BLOCKQUOTE>
        <UL>
          <UL>
            <LI>Using the <FONT color=3D#990099>Save in</FONT> drop-down =
menu,=20
            specify the folder (directory) where you'll save your file. =
In this=20
            example, the directory is <CODE>java</CODE> on the =
<CODE>C</CODE>=20
            drive.=20
            <LI>In the <FONT color=3D#990099>File name</FONT> text box, =
type=20
            <CODE>"HelloWorldApp.java"</CODE>, including the double =
quotation=20
            marks.=20
            <LI>From the <FONT color=3D#990099>Save as type</FONT> =
drop-down menu,=20
            choose <FONT color=3D#990099>Text Document</FONT>.&nbsp; =
</LI></UL></UL>
        <BLOCKQUOTE>When you're finished, the dialog box should look =
like=20
          this:=20
          <P>
          <CENTER><IMG height=3D165 alt=3D""=20
          =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/saveas.=
gif"=20
          width=3D426 align=3Dbottom NATURALSIZEFLAG=3D"3"></CENTER>
          <P></P>Now click <FONT color=3D#990099>Save</FONT>, and exit =
NotePad.=20
        </BLOCKQUOTE><IMG height=3D16 alt=3D""=20
        =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/arrow.g=
if"=20
        width=3D13><FONT size=3D-1><A=20
        =
href=3D"http://java.sun.com/docs/books/tutorial/getStarted/cupojava/win32=
.html#top">top</A></FONT>=20
        <BR>
        <HR align=3Dleft width=3D"70%">

        <H2><A name=3D2b></A><FONT face=3D"Arial, Helvetica, =
sans-serif"><FONT=20
        color=3D#ff0000>b. </FONT>Compile the Source File.</FONT></H2>
        <BLOCKQUOTE>
          <P>From the <FONT color=3D#990099>Start</FONT> menu, select =
the <FONT=20
          color=3D#990099>MS-DOS Prompt</FONT> application (Windows =
95/98) or=20
          <FONT color=3D#990099>Command Prompt</FONT> application =
(Windows NT).=20
          When the application launches, it should look like this:</P>
          <P>
          <CENTER><IMG height=3D120 alt=3D""=20
          =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/dos.gif=
"=20
          width=3D489 align=3Dbottom NATURALSIZEFLAG=3D"3"></CENTER>
          <P></P>
          <P>The prompt shows your <I>current directory</I>. When you =
bring up=20
          the prompt for Windows 95/98, your current directory is =
usually=20
          <CODE>WINDOWS</CODE> on your <CODE>C</CODE> drive (as shown =
above) or=20
          <CODE>WINNT</CODE> for Windows NT. To compile your source code =
file,=20
          change your current directory to the directory where your file =
is=20
          located. For example, if your source directory is =
<CODE>java</CODE> on=20
          the <CODE>C</CODE> drive, you would type the following command =
at the=20
          prompt and press <FONT color=3D#990099>Enter</FONT>:</P>
          <BLOCKQUOTE>
            <TABLE cellSpacing=3D2 cellPadding=3D0 border=3D1>
              <TBODY>
              <TR>
                <TD width=3D"100%"><CODE>&nbsp;cd=20
              =
c:\java&nbsp;</CODE></TD></TR></TBODY></TABLE></BLOCKQUOTE>
          <P>Now the prompt should change to =
<CODE>C:\java&gt;</CODE>.</P>
          <BLOCKQUOTE>
            <HR align=3Dleft>
            <B>Note: </B>To change to a directory on a different drive, =
you must=20
            type an extra command. <BR>&nbsp;=20
            <TABLE cellSpacing=3D2 cellPadding=3D0 width=3D486 =
border=3D0>
              <TBODY>
              <TR>
                <TD width=3D"50%"><IMG height=3D68 alt=3D""=20
                  =
src=3D"http://java.sun.com/docs/books/tutorial/figures/getStarted/extrast=
ep.gif"=20
                  width=3D198> </TD>
                <TD width=3D"50%">As shown here, to change to the=20
                  <CODE>java</CODE> directory on the <CODE>D</CODE> =
drive, you=20
                  must reenter the drive, =
<CODE>d:</CODE></TD></TR></TBODY></TABLE>
            <HR align=3Dleft>
          </BLOCKQUOTE>
          <P>If you enter <CODE>dir</CODE> at the prompt, you should see =
your=20
          file.</P>
          <P>
          <CENTER><IMG height=3D260 alt=3D""=20
          =