BeanBuilder Example

In this example I will create a simple calculator with Demeter/Java, my BeanBuilder, and Suns BDK. This examples assumes you are using a UNIX system. The calculator accepts simple expressions and supports only addition and multiplication. It is implemented is the following Demeter/Java files:

In addition a beanspec file is created that instructs the BeanBuilder on how to package the bean. That file is Calc.beanspec .

Building the JavaBean

To build the calculator bean perform the following steps:

demjava -aspect -code -grammar Calc.cd Calc.beh
cd gen
java BeanBuilder.Main ../Calc.beanspec
java EDU.neu.ccs.demeter.tools.weaver.WMain Calc.asp CalcBean.asp
cp javafiles/* .
javacc grammar.jj
javac -d . *.java
jar -cvfm Calc.jar Calc.manifest calc

Creating an Application with Suns BeanBox

Copy the Calc.jar file into the jars directory so the BeanBox can find it.
Start the BeanBox. See Suns documentation for details. Note: Make sure the Demeter/Java classes are included in the class path. I modified run.sh so the demjava.jar was in the CLASSPATH.
When the BeanBox starts you will notice that the Calc bean now appears in the tool box. Note: An EquationField bean has been added for this demo too. Download it by saving EquationField.jar or compile EquationField.java.
Add the EquationField, ExplicitButton, and the Calc beans to the BeanBox.
Link the EquationField with the Calc beans together via the TextEvent event and the Calc.setExpr() method.
- Select the EquationField bean.
- Select the Edit/Events/text/textValueChanged menu item.
- Select the Calc bean.
- Then select the setExpr target method in the EventTargetDialog.
Link the ExplicitButton and the Calc beans together via the ActionEvent event and the Calc.exec() method.
- Select the ExplicitButton bean.
- Select the Edit/Events/button push/actionPerformed menu item.
- Select the Calc bean.
- Then select the exec target method from the EventTargetDialog.
At this point the application is built. Select the View/Disable Design Mode menu item. Enter an expression in the EquationField, then press the button. The result will be calculated by the Calc bean an printed on stdout.