13 Java-Related Issues

13.1 Using oracle.ewt Classes in Pluggable Java Components

Pluggable Java Components (PJCs) and JavaBeans use classes that are part of the oracle.ewt framework. The sample PJCs and JavaBeans provided by Oracle are re-coded to use Swing classes or oracle.ewt classes. When upgrading to Oracle Forms, there are steps you must take to ensure equivalent functionality.

• The Oracle Forms Jar files (frmall.jar and frmall_jinit.jar) contain only the EWT classes that are required by the Forms Java Client. Therefore, PJCs that had been used with Forms 6i may fail at runtime in Oracle Forms because the classes that were available in Forms 6i can no longer be located. Missing oracle.ewt classes are available in ewt.jar, which is supplied with Oracle JDeveloper.

• Because of security constraints related to Java 1.3 and later (Oracle Forms 11g uses Java 1.6), you must re-sign all of the classes (including the Forms classes) with your own certificate. Java 1.3 requires that all classes from the same package be signed with the same certificate. Therefore, to use extra classes from ewt.jar in combination with frmall.jar, you must re-sign all of the classes with your own certificate.

13.2 JDK Versions and Font-Rendering Issues

When upgrading Forms applications from JDK 1.1 to JDK 1.3 or higher, you may encounter font height changes. This is because the code that renders fonts underwent significant changes from JDK 1.1 to JDK 1.3. As a result of these changes, the font height for logical fonts of the same size increased in JDK 1.3. For example, a dialog font of size 12 points has a height of 15 points in JDK 1.1 and a height of 17 points in JDK 1.3.

In Forms applications, the font size changes may affect labels, which can overlap text fields. One possible workrooms is to set the following applet parameter to "yes":

<PARAM NAME = "mapFonts" VALUE = "yes" >

After making this change, check the appearance of the font size to be sure it is acceptable. Modify the form if this workaround does not provide acceptable font sizes. See the Oracle Fusion Middleware Forms Services Deployment Guide for details.

Another workaround is that when the font is unspecified, the default font name and size in Registry.dat is used. The default font in registry.dat is Dialog with a default size of 900. The size of this font can be modified to a smaller value in the registry.dat file. In cases where the font is not specified, you can work around the problem without modifying the form. However, use caution because it modifies the font size for the entire application.