Create a new Application workspace to hold the business model components. Select File | New, then select the Application workspace node.
Click OK.

This will open a dialog where you can define location, templates, and application package prefix

Change the name of the application to HRApplication. Accept the other defaults for the application and click OK.

On completion you should have an application named HRApplication and two projects named Model and ViewController. You will only use the Model project for this exercise.

It is generally easier and more effective to start with a set of default business components than to create each one individually. Whichever technique you use will result in a set of components that you can customize to fit your specific business needs.

To create a set of default business components, right-click the Model project node in the System Navigator and select New.

This opens the New Gallery wizard. From this gallery, select the Business Components category and Business Components from Tables and click OK. You can also double-click Business Components from Tables.

Selecting Business Components from Tables opens the Business Components wizard. The first step of this wizard is to establish a connection to your database. Select the connection name that connects to the HR schema. If the welcome page is displayed, click Next to go the step 1 of the wizard.

Note: If you have not established this connection to the HR schema, please see the prerequisites section.

In step 1 of the Business Component wizard, select the tables for which you want to create entity objects. Select the Departments, and Employees tables.

In step 2 of the wizard, select which view objects you want to create from the default entity objects These view objects will be updateable. In the next step, you can create view objects that are read-only and that are based on tables, not on entity objects. Select all of the available entity objects and click the shuttle button.

In step 3 of the wizard, you can create view objects that are based on tables, not on entity objects. These view objects are useful for any view that will not be updateable.

In step 4 of the wizard, change the name of the Application Module to HRAppModule. If the Application Module checkbox is checked, the wizard will create a default application module for you.

If it is not checked, check it.

The last step of the wizard confirms what Business Component objects you are about to create. Click Finish to accept your choices.

Your project should now include an application module with entity and view objects.

JDeveloper includes a built-in Business Components Browser that tests business components. The browser works without requiring you to build any client code.

To invoke the tester, right-click the Application Module you just created in the System Navigator and select Test from the context menu.

The first step of the Tester is to select a database connection to use for this test. Select the database connection you used to create the default objects and click Connect.

The Business Components Browser shows all of the View objects defined in your Application Module.

Double-click a view object instance to display a single-record data viewer.

You can scroll through the rows in this View object using the controls on the top of the window. You can double-click other View objects to run multiple data viewers.

The Business Components Browser gives you a view of the application module that you have just created.

When you are finished testing your application, close the Business Components Browser.

In the System Navigator, click HRAppModule. This will show the contents of the Application Module in the Structure pane. Notice the two source files: HRAppModule.xml and HRAppModuleImpl.java

Double click the source file HRAppModuleImpl.java to open the code editor.

Now that we have a code editor open, we can start adding the custom code. The first step is to create the method signature.
Enter the following code after the end of the default constructor.

 public Number getDeptSalaryTotal(String dept_id){   
return 
new Number(0);}

Since we will be using the Oracle implementation of Number, add an import statement to the top of the class as follows:

import oracle.jbo.domain.Number;

You should compile your class periodically to make sure that you have not introduced errors in your code that the compiler will catch. To compile the class, right-click anywhere in the code editor window and select Make from the context menu.

Check the message window for any compile errors. If there were no errors, the compilation was successful.

Before you can use data from the Departments View Object, you must instantiate it. JDeveloper ADF provides methods that make this a simple task. To instantiate the view object call getDepartmentsView1() to your method.

 // get a department view object DepartmentsViewImpl 
dept = getDepartmentsView1();

Once you have access to the Departments View object, you can manipulate it by calling standard methods on the object. In our case, we need to modify the where clause to include the department ID. Add the following code to your method which:

• Sets the where clause
• Executes the query
• Sets the current row to the first row of the rowset

   public 
  HRAppModuleImpl() { }

   public Number getDeptSalaryTotal (String dept_id) 
  { // get a department view object 
  DepartmentsViewImpl dept = this.getDepartmentsView1(); 
  dept.setWhereClause("DEPARTMENT_ID = " + dept_id); 
  dept.executeQuery(); 
  dept.first(); return new Number(0); }

Make sure to compile your code periodically to find any coding errors you may have introduced.

Next you will use another method that is part of ADF Business Components to get all of the Employees that are related to the Department you just retrieved. To get the Employee rows, add a call to the getEmployeesView3() method.

EmployeesViewImpl 
emps = getEmployeesView3(); 

The ADF Business Components framework automatically coordinates the master detail relationship between Departments and Employees. This means the Employee rowset you just created will contain only Employees that belong to the department you queried in the previous step. Now all you have to do is loop through the Employee rows and summarize the salary attribute.
Before you can loop through the Rows, you need to import oracle.jbo.Row. JDeveloper provides automatic advice on import statements. When you enter the following code, you will notice that JDeveloper underlines the Row object and prompts you to import oracle.jbo.Row. If you hit Alt + Enter, JDeveloper will add the import for you.
You need to create a temporary RowSetIterator. You will use this iterator to loop through the employee rows.When you are through with the iterator, make sure to close it.

Number salaryTotal = new Number(0);
 

RowSetIterator empsIter = emps.createRowSetIterator(null);
while(empsIter.hasNext())
{ 
Row empsRow = (Row)empsIter.next();
salaryTotal = salaryTotal.add((Number)
(empsRow.getAttribute("Salary")));
}
empsIter.closeRowSetIterator();
return 
salaryTotal; 

Your completed method should look like the following:

public Number getDeptSalaryTotal(String 
dept_id)
{
// get a department view object
 DepartmentsViewImpl dept 
= getDepartmentsView1();
 dept.setWhereClause("DEPARTMENT_ID = " 
+ dept_id);
 dept.executeQuery();
 dept.first();
 
 EmployeesViewImpl 
emps = getEmployeesView3();
 
 Number salaryTotal = new Number(0);
 
 
RowSetIterator empsIter = emps.createRowSetIterator(null);
 while(empsIter.hasNext())
 
{
 Row empsRow = (Row)empsIter.next();
 salaryTotal = salaryTotal.add((Number)
 (empsRow.getAttribute("Salary")));
 
}
 empsIter.closeRowSetIterator();
 return salaryTotal;
}

In the System Navigator, right-click the Model project and select New from the context menu.

In the New Gallery, select Simple Files and Java Class. This will open the Create Java Class Wizard.

In the Java Class Wizard, rename the class to TestClient. Make sure to check the box that has the wizard create a Main method for you. Click OK to accept all the other default values.

JDeveloper has now created a simple Java class named TestClient and has opened it in the editor window. The next step will be to add the code to test your custom method.

First, let's create a couple of String variables to hold the name of the application module and the name of the configuration. The application module name is whatever you named it when you created the Business Components. It should be HRAppModule. The default configuration name is the application module name appended with Local (HRAppModuleLocal). You also need to include the package name as part of the application module. Add the following code the your TestClient. The code will go within the Main() method and replaces the default code "TestClient testClient = new TestClient();"

 String amDef = "model.HRAppModule";
 String config = "HRAppModuleLocal";

Next we'll call a method the instantiate the application module. The method we call accepts two arguments: the application module name, including the package name, and the configuration name. For the next few steps, you will import the classes that are required by letting JDeveloper remind you which ones are needed and hitting Alt+Enter to include the import. Add the following code:

 ApplicationModule am = 
 Configuration.createRootApplicationModule(amDef, 
config);

Now that we have an generic application module, we will need to cast it to our specific application module. This will allow us access to any application specific code you have added, like your custom method. Add the following line of code to cast the application module.

 HRAppModuleImpl myAm = (HRAppModuleImpl)am;

At this point, you should be able to compile and run your class. It won't do anything interesting but it will prove that your code can successfully find and instantiate the application module.
To run the application, right-click anywhere in the code editor window and select run. Your program should run successfully. Your code should look like the following:

package model;
import oracle.jbo.ApplicationModule;
import oracle.jbo.client.Configuration;

public 
class TestClient { public TestClient() { }

 /** * * @param args */ public 
static void main(String[] args) 
{ 
String amDef = "model.HRAppModule"; 
String config = "HRAppModuleLocal"; ApplicationModule am = 
Configuration.createRootApplicationModule(amDef, 
config); HRAppModuleImpl myAm = (HRAppModuleImpl)am; 
} 
} 

Now that we have an instance of our application module, we can simply call the method. Remember that the method returns an oracle.jbo.domain.Number object. The following code calls the method. Notice that we have hardcoded the department Id. We could have passed an argument to the program but this is a little easier for now. When you create a more robust client application, you will call the method with a department number probably derived from a form field or the like.

Number salaryTotal 
= myAm.getDeptSalaryTotal("10");

That last line of code set your salaryTotal variable to the results of the call. All we have left to do is display the results. You can display the results by calling System.out.println() with some text concatenated with salaryTotal variable. The code should look like:

 System.out.println("Total 
salary for Department 10: " + salaryTotal);

Now we need to do a little housekeeping. Whenever you create an instance of an application module, you should remove it when you are done. The last step in creating this test client is to release the application module. The code for that is:

 Configuration.releaseRootApplicationModule(am,true);

You have successfully created a test client that calls your custom method. Your code should look like:

package model;
import oracle.jbo.ApplicationModule;
import oracle.jbo.client.Configuration;
import 
oracle.jbo.domain.Number;

public class TestClient { public TestClient() 
{ }

 /** * * @param args */ public static void main(String[] args) { 
String amDef = "model.HRAppModule"; 
String config = "HRAppModuleLocal"; 
ApplicationModule am = 
Configuration.createRootApplicationModule(amDef, config); 
HRAppModuleImpl myAm = (HRAppModuleImpl)am; 
Number salaryTotal = 
myAm.getDeptSalaryTotal("10"); 
System.out.println
("Total salary for Department 10: " + salaryTotal); 
Configuration.releaseRootApplicationModule(am,true); } } 

Of course the last step is to run the TestClient to see the results. Remember, to run an application, right-click anywhere in the code editor and select Run from the context menu. You will see the results in the message window at the bottom of the JDeveloper window.