ch39.htm

Java_by_Example,初级经典例子哦,珍藏版本

		show();

	}

	

	public boolean handleEvent(Event e) {

		if (e.id == Event.WINDOW_DESTROY) {

			dispose();

			return true;

		} else 

			return super.handleEvent(e);

	}



	public static void main(String args[]) {

		myFrame app = new myFrame("myFrame");

	}

}

</PRE>

</BLOCKQUOTE>

<HR>

<P>

<CENTER>

<TABLE BORDER=1 WIDTH=80%>

<TR VALIGN=TOP><TD><B>NOTE</B></TD></TR>

<TR VALIGN=TOP><TD>

<BLOCKQUOTE>

You'll notice that the color of various words change as you enter the listing into the Diva editor. This cool feature is called syntax highlighting.</BLOCKQUOTE>



</TD></TR>

</TABLE>

</CENTER>

<BLOCKQUOTE>

</BLOCKQUOTE>



<LI>Enter Listing D.1 into the editor window. When done, select

File, Save and use myFrame.java as the file name. The file name

and the class name must be identical in order to compile. As you

save, Diva will ask if you want to add the file to the current

project. Say yes. The saved file will be added to the myFrame

project, as shown in Figure C.4.<BR>

<A HREF="fc-4.gif"><B>Figure C.4</B> : <I>myFrame.java is now part of the myFrame project</I>.</A>

<LI>Select Build, Compile Active Java File. This will start the

javac compiler. Any messages produced by the compiler will be

displayed in the window along the bottom of the IDE.

<LI>Right-click the myJava.java file in the project window, and

then select Project Settings from the context menu. The Settings

for the open project dialog box should appear with the Files tab

displayed. If not, select the Files tab.

<LI>Click myFrame.java entry in the list and then click Mark as

&quot;main.&quot; This lets Diva know which Java file contains

the main procedure. You'll notice that myFrame.java is now marked

with a yellow star in the project window. You click OK to close

the dialog box.

<LI>Click Build, Run Java to display the Run java dialog box.

Then, click the Run button to actually start the Java interpreter.

First, a DOS Window will appear entitled Java Console and then

the myFrame application will appear.

<LI>Click the Close button to exit the myFrame application.

</OL>

<P>

The Java console will continue running after the Java application

is finished. Leave it running. It will be used for the next interpreted

Java program that you run. After you close Diva, you can click

the Close button of the DOS window to close it also. Be warned,

however, that it may take a while to close.

<H4>The Hierarchy Window</H4>

<P>

The middle window in the top row of the Diva IDE shows the hierarchy

of the open Java file. Figure C.5 shows the Hierarchy window for

myFrame.java file.

<P>

<A HREF="fc-5.gif"><B>Figure C.5</B> : <I>The Hierarchy window for myFrame.java</I>.</A>

<P>

The Hierarchy window is very useful because you can collapse and

expand sections of the file so that it's easy to see what a file

contains-handy when looking at someone else's code. You'll also

see that all of the procedures are shown. You can click any procedure

name, and its corresponding code will be displayed.

<H4>Other Features</H4>

<P>

Diva has a primitive user interface design ability. You access

this by creating a new file and selecting Diva Design Document

as the new file type. However, very little documentation exists

for this feature. You might be better off waiting for the beta

version.

<P>

You can also use Diva to automatically generate skeleton code

to handle a variety of common programming situations. Figure C.6

shows part of the list of code snippets that Diva has available.

You access this list by selecting Edit, Insert Skeleton Code.

<P>

<A HREF="fc-6.gif"><B>Figure C.6</B> : <I>Diva lets you insert code snippets by selecting from a list</I>.</A>

<P>

You can also add your own code to the list of snippets so that

you can share code with other programmers or simply avoid retyping.

<H3><A NAME="Java">

Java+</A></H3>

<P>

The Java+ IDE, shown in Figure C.7, seems to be designed to work

with applets. You can compile your Java classes and the IDE will

display any compiler messages in a separate window. This IDE does

not use project files to group source files. Therefore, it is

useful for only small development projects.

<P>

<A HREF="fc-7.gif"><B>Figure C.7</B> : <I>The myFrame.java file inside the Java+ IDE</I>.</A>

<H3><A NAME="JavaMaker">

JavaMaker</A></H3>

<P>

This is another IDE that automates the compilation process. It

does have a nice Print Preview mode so that you can see how your

Java code will print. Some people like to try to have only one

procedure per page so that the code is more understandable. You

can also launch the compiler and Appletviewer from inside the

IDE. Figure C.8 shows what the myFrame.java file and the output

of the compiler looks like inside the JavaMaker IDE.

<P>

<A HREF="fc-8.gif"><B>Figure C.8</B> : <I>The myFrame.java file inside the JavaMaker IDE</I>.</A>

<H2><A NAME="Tools"><FONT SIZE=5 COLOR=#Ff0000>

Tools</FONT></A></H2>

<P>

There are some programs out on the Net that are not directly related

to compiling and running Java programs. Some programs will help

you create a base program to start your project, and some will

help with finding Java documentation.

<P>

This section describes a few of the tools that are available.

<H3><A NAME="AppletGen">

AppletGen</A></H3>

<P>

This extremely useful program is a source code generator. AppletGen

creates a skeleton applet customized according to your needs.

It has no provisions to help you compile or edit the code; it

simply generates a text file. However, this ability might come

in very handy. For example, it will free you from needing to remember

how to add a menu to a frame. If you specify that your applet

needs a menu, the basic menu code will be added to the text file.

<P>

When AppletGen is first started, you will see the window shown

in Figure C.9.

<P>

<A HREF="fc-9.gif"><B>Figure C.9</B> : <I>The AppletGen program</I>.</A>

<P>

As you can see, AppletGen has eight tabs. Here is a summary of

the tabs:

<BLOCKQUOTE>

Applet Info-This tab lets you add some documentation to your applet.

You can also specify which packages you need to import.

</BLOCKQUOTE>

<BLOCKQUOTE>

Applet Tab-This tab lets you specify the information that will

be added to the <TT>&lt;applet&gt;</TT> HTML tag when AppletGen

generates a HTML file. You can also list out the parameters needed

for your applet.

</BLOCKQUOTE>

<BLOCKQUOTE>

Applet Attributes-This tab has two subtabs. One, called Options,

lets you select the font, colors, and determine if menus, frames,

or a stand-alone app is used. The other, called Constants, lets

you enter a list of constants that your applet will be using.

</BLOCKQUOTE>

<BLOCKQUOTE>

Events-This tab lets you select which events your applet will

respond to. Procedure stubs will be created for each events that

you select.

</BLOCKQUOTE>

<BLOCKQUOTE>

Threading-Shown in Figure D.9 above, this tab will let you specify

information about how you would like threads to be used in your

application.

</BLOCKQUOTE>

<BLOCKQUOTE>

URLs-You can indicate which URLs your applet will be using as

a resource.

</BLOCKQUOTE>

<BLOCKQUOTE>

Resources-This is a listing of the AU, GIF, or JPEG files that

your applet will be using. If the files are not local, the resource

names defined on the URLs tab will be used.

</BLOCKQUOTE>

<BLOCKQUOTE>

Code Options-This tab lets you determine which types of files

AppletGen will create. You can choose to create HTML, Java Code,

Documentation, Debug info, and an INI file. The INI file stores

all of the choices that you made during the AppletGen session.

</BLOCKQUOTE>

<BLOCKQUOTE>

Code Window-This tab displays the Source code that AppletGen has

created. You can also see the HTML and INI files. Each type of

file has its own subtab. You need to click the button near the

file name (top left of the tab) in order to save the files.

</BLOCKQUOTE>

<P>

The AppletGen program is great if you are just learning Java.

By changing the options on the various tabs and then looking at

the source code that is generated, you will be able to see a lot

of different situations. In addition, you can always recreate

any given situation if you need a base of code to start developing

from.

<P>

<CENTER>

<TABLE BORDER=1 WIDTH=80%>

<TR VALIGN=TOP><TD><B>NOTE</B></TD></TR>

<TR VALIGN=TOP><TD>

<BLOCKQUOTE>

You can download this application-in beta form-from <A TARGET="resource window" HREF="http://ugWeb.cs.ualberta.ca/~nelson/AppletGen/AppletGen1.html.">http://ugWeb.cs.ualberta.ca/~nelson/AppletGen/AppletGen1.html.</A></BLOCKQUOTE>



</TD></TR>

</TABLE>

</CENTER>

<P>

<H3><A NAME="VbToJava">

VbToJava</A></H3>

<P>

This application will let you design using Visual Basic and then

convert the design into Java code. It has only one screen, shown

in Figure C.10, which lets you specify which FRM file to convert.

You will also need to specify the Java class name and .java file

to create.

<P>

<A HREF="fc-10.gif"><B>Figure C.10</B> : <I>The Visual Basic to Java Convertor</I>.</A>

<H3><A NAME="PortaFilter">

PortaFilter</A></H3>

<P>

The Java documentation is a little difficult to search because

it is in HTML format. Bill Bercik has converted the documentation

into the Windows Help format and made the files available for

you to download. You can download the 1.4M file by looking at

this URL:

<BLOCKQUOTE>

<PRE>

<A TARGET="resource window" HREF="http://www.dippybird.com/download.html

">http://www.dippybird.com/download.html

</A></PRE>

</BLOCKQUOTE>

<P>

The following documents have been converted into the Windows Help

format:

<BLOCKQUOTE>

Java-- Language Specification

</BLOCKQUOTE>

<BLOCKQUOTE>

Java-- White Paper

</BLOCKQUOTE>

<BLOCKQUOTE>

Java-- API

</BLOCKQUOTE>

<BLOCKQUOTE>

Java-- Man Pages

</BLOCKQUOTE>

<BLOCKQUOTE>

Java-- Virtual Machine Specification

</BLOCKQUOTE>

<BLOCKQUOTE>

Java-- FAQ's

</BLOCKQUOTE>

<BLOCKQUOTE>

Java-- Tips and Tricks

</BLOCKQUOTE>

<BLOCKQUOTE>

Java-- Resource Guide

</BLOCKQUOTE>

<P>

The help file was last updated on March 3, 1996, so it is pretty

up-to-date.

<H2><A NAME="Summary"><FONT SIZE=5 COLOR=#Ff0000>

Summary</FONT></A></H2>

<P>

This has been a small sampling of the IDEs and tools available

to you for downloading from the net. By monitoring the comp.lang.java

newsgroup, or searching the Alta Vista for Java + IDE, you can

easily find others. Take a few moments to look at each tool to

see if it will be useful to you. Every programmer uses a different

set of utilities and it takes effort to find the set that is right

for you.

<P>

One important determinate of which tools to use is the scope of

your project. If you are just learning Java, your tools should

be simple and easy to learn. If you are an accomplished programmer,

using a complicated tool with many options might make more sense.

Similarly, if you are developing a large program, a tool that

tracks many files in a project-oriented way like Diva will be

more useful than Java+, which does not.

<P>

Finally, the Java language itself is still evolving. It will change

and so will the tools that support it. Java has a bright future

ahead. Don't be blinded by it and don't wait for the perfect tool.

Start coding today!

<HR>











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