Creating a FunctionCall class

The FunctionCall class contains definitions for your custom functions. It also registers the FunctionCall object and each of the custom functions that it supports with the Forms System so that the functions and packages that it contains will be recognized.

Create a new Java™ source file called FciFunctionCall.java.
Define the Java package. For example:
```
   com.yourcompany.samples;
```

Import the following API packages:

   com.ibm.form.api.ifx.IFX
   com.ibm.form.api.xfdl.FormNodeP
   com.ibm.form.api.xfdl.FunctionCallManager
   com.ibm.form.api.xfdl.FunctionCallImplBase
   com.ibm.form.api.xfdl.FunctionCall
   com.ibm.form.api.error.UWIException

Import any other required files. In this case the following files are needed to implement the convertDate function:

   java.util.Date
   java.util.Locale
   java.text.DateFormat
   java.text.SimpleDateFormat
   java.text.ParseException

Create a FunctionCall class that extends the pre-defined superclass com.ibm.form.api.xfdl.FunctionCallImplBase and implements the pre-defined interface FunctionCall.
- In the following example the name of the FunctionCall class is FciFunctionCall.
```
   public class FciFunctionCall extends FunctionCallImplBase 
      implements FunctionCall
      {
         /* Additional code removed */ 
      }
```
Define a unique identification number for each custom function that you are going to create using the FCI.
- In the following example,FciFunctionCall contains a function called convertDate that converts any date to the date format and language of a specific country. The convertDate function in FciFunctionCall has an ID number of 1:
```
   public class FciFunctionCall extends FunctionCallImplBase 
      implements FunctionCall
      {
         public static final int CONVERTDATE = 1;
         /* Additional code removed */ 
      }
```
Define a FunctionCall class constructor that takes as its parameter the IFX Manager.
- In the following example, the constructor for the FciFunctionCall class is FciFunctionCall.
```
   public class FciFunctionCall extends FunctionCallImplBase 
      implements FunctionCall
      {
         public static final int CONVERTDATE = 1;
         
         public FciFunctionCall(IFX IFXMan) throws UWIException
         {
               /* Additional code removed */ 
         }
      }
```
- The IFXMan object represents the IFX Manager. Through this object all other objects and services can be reached.
- UWIException is a generic exception.