Java Programming Netbeans

[Sourn Rose]

Its time to write your first application! These detailed instructions are for users of the NetBeans IDE. The NetBeans IDE runs on the Java platform, which means that you can use it with any operating system for which there is a JDK available. These operating systems include Microsoft Windows, Solaris OS, Linux, and Mac OS X.

When you create an IDE project, you create an environment in which to build and run your applications. Using IDE projects eliminates configuration issues normally associated with developing on the command line. You can build or run your application by choosing a single menu item within the IDE.

A source file contains code, written in the Java programming language, that you and other programmers can understand. As part of creating an IDE project, a skeleton source file will be automatically generated. You will then modify the source file to add the "Hello World!" message.

The IDE invokes the Java programming language compiler (javac), which takes your source file and translates its text into instructions that the Java virtual machine can understand. The instructions contained within this file are known as bytecodes.

To set this JDK as the default for all projects, you can run the IDE with the --jdkhome switch on the command line, or by entering the path to the JDK in the netbeans_j2sdkhome property of your INSTALLATION_DIRECTORY/etc/netbeans.conf file.

When you created this project, you left the Create Main Class checkcbox selected in the New Project wizard. The IDE has therefore created a skeleton class for you. You can add the "Hello World!" message to the skeleton code by replacing the line:

If the build output concludes with the statement BUILD FAILED, you probably have a syntax error in your code. Errors are reported in the Output window as hyperlinked text. You double-click such a hyperlink to navigate to the source of an error. You can then fix the error and once again choose Run Build Project.

When you build the project, the bytecode file HelloWorldApp.class is generated. You can see where the new file is generated by opening the Files window and expanding the Hello World App/build/classes/helloworldapp node as shown in the following figure.

The next few pages of the tutorial will explain the code in this simple application. After that, the lessons go deeper into core language features and provide many more examples. Although the rest of the tutorial does not give specific instructions about using the NetBeans IDE, you can easily use the IDE to write and run the sample code. The following are some tips on using the IDE and explanations of some IDE behavior that you are likely to see:

Once you have created a project in the IDE, you can add files to the project using the New File wizard. Choose File New File, and then select a template in the wizard, such as the Empty Java File template.

You can compile and run an individual file (as opposed to a whole project) using the IDE's Compile File (F9) and Run File (Shift-F6) commands. If you use the Run Main Project command, the IDE will run the file that the IDE associates as the main class of the main project. Therefore, if you create an additional class in your HelloWorldApp project and then try to run that file with the Run Main Project command, the IDE will run the HelloWorldApp file instead.

As you are typing in the IDE, a code completion box might periodically appear. You can either ignore the code completion box and keep typing, or you can select one of the suggested expressions. If you would prefer not to have the code completion box automatically appear, you can turn off the feature. Choose Tools Options Editor, click the Code Completion tab and clear the Auto Popup Completion Window check box.

If you want to rename the node for a source file in the Projects window, choose Refactor from IDE's main menu. The IDE prompts you with the Rename dialog box to lead you through the options of renaming the class and the updating of code that refers to that class. Make the changes and click Refactor to apply the changes. This sequence of clicks might seem unnecessary if you have just a single class in your project, but it is very useful when your changes affect other parts of your code in larger projects.

Figure 4: Adding a LibraryIf the import is successful, the imported jar file will be shown in the projects list.

Figure 5: The imported jar file is shown in the projects listNow that everything is set, we can start our code in Java.Step 5: Creating the ApplicationThere a few thing common to Java code in implementing a JDBC application. The package that contains all the required classes and interfaces for JDBC programming is java.sql. The exceptions that may occur are handled by the object of the SQLException reference defined in the same package.

When we put these together, it looks like this. This is the code we write inside the SimpleJDBCApplication.java source file, which basically fetches the record we have inserted in the books table we have created.

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