1. Field Trip #22 Creating an Excel Spreadsheet with Java By Keith Lynn

2. Java Frame To contain the contents of the Excel document, we will create a JFrame A JFrame is a graphical interface It can contains components that hold the data of the spreadsheet It can also contain a menu bar which gives an interface to the user

3. LayoutManager When we create a JFrame, we can specify how components will be layed out There are built-in layout managers like FlowLayout which will arrange components in a arow and GridLayout which will arrange components in a grid We set a layout with setLayout

4. JMenuItem We can create a JMenuItem and add it to a JMenu We can add the JMenu to a JMenuBar We can display the JMenuBar with the method setMenuBar The Menus appear in the upper left corner

5. Handling Events When we select a menu item, it creates an event In order to detect and act on the event, we attach an ActionListener to the JMenuItem ActionListener is an interface in the java.awt.event package that contains the method actionPerformed

6. Interfaces An interface is a special type of Java program that lists methods In order to use the interface, we must implement all of the methods in the interface ActionListener is found in the java.awt.event package When we attach an ActionListener to a JmenuItem, and select the item, the actionPerformed method is called We can determine the label of the JmenuItem, we use the method getActionCommand()

7. Packages Packages are collections of related classes In order to use the classes in a package, we can import them into our class It is not necessary to import packages We can use the fully qualified name of the class This is necessary if there are two packages we are using and there is a class in each package with the same name Note the import statement is not recursive

8. CLASSPATH The CLASSPATH is an environment variable that determines what directories are searched to find a class Jar files are archive files that contain Java classes If we want to include a class from a jar file in our class, we place the absolute path of the jar file in the CLASSPATH

9. POI POI, Poor Obfuscation Interface, is a project that aims to provide a Java API to read various file formats based on the Office Open XML Standard In order to read and write Excel documents, we can import the org.apache.poi.xssf.usermodel package In order to open an Excel document, we create a FileInputStream to open the document We create an instance of an XSSFWorkbook using the FileInputStream XSSFWorkbook represents the entire document

10. Sheets The XSSFWorkbook is made up of one or more XSSFSheet objects Each XSSFSheet represents a worksheet The XSSFSheet is composed of XSSFRow objects Each XSSFRow object is composed of XSSFCell objects

11. JTable To display the information on the JFrame, we will create an instance of a JTable In order to create the JTable, we need to specify a one dimensional array containing column names and a two dimensional array containing the data We then access the data of the worksheet and place that information in the JTable

12. Creating a Chart To create a new chart, we create a new instance of an XSSFWorkbook We then create a new XSSFSheet When then create rows and place data in cells We can create a new cell and set its value with setCellValue

13. Writing the Spreadsheet In order to write the spreadsheet, we create an instance of a FileOutputStream attached to a file After we create the XSSFWorkbook, we call the write method and send the FileOutputStream