JTables

JTables

Creating a Simple JTable

• Create a String array that contains the headings that you would like to see at the top of the JTable 
• Initialize all the entries into a double dimension object array (Will have to constantly edit this list. Instead of the AotearoaAccommodation Array, use a double dimension object array 
• Create a JTable using (object data array, column name). 
• Can also use JTable (row data, column data) or JTable (Vector rowData, Vector columnData)
• These constructors automatically make every single text editable 
• They treat everything as a string, so instead of showing a check box or something, it'll end up showing "true" or "false"
• They force you to put all your data into an array or a vector.

Adding an Array to A Container

• Create a JScrollPane with the table in the brackets. (i.e.: JScrollPane scrollPane = new JScrollPane(table); 
• Then, setFillsViewPort(true); 
• JScrollPane is telling Java to add the table to the scroll pane. 
• setFillsViewPort(true) tells Java to allow drag and drop (by expanding or decreasing column lengths). 

User Selections

• In the normal config, it is totally fine with multiple selections I don't see how I need this in the program though. It's not like the program can sort by 2 headings.

Creating a A Table Model

• All table models use a table model object. 
• If the user does not specify what type of model object, java automatically creates the DefaultTableModel.
• Simple Model Object vs Table Demo (Simple JTable)
• The Simple Model Object has the ability to recognize what is a number, what is a boolean and what a string is. In this case, we can represent a boolean by a JCheckBox and sort by numbers unlike in the previous table example. 
• Simple Table does not let you edit the table headings. You can do this in the Simple Model Object (not sure if I want it to though). 

Listening for Data Changes

• Can use the TableModelListener 
• Notified when the data in the table is changed (if I set it to uneditable, it shouldn't be changed by the user). 

Data Change Events 

• Your class must invoke one of the data change events:
• fireTableCellUpdated: Update of one specific cell
• fireTableRowsUpdated: Update of one row
• fireTableDataChanged: Update of entire table (data only)
• fireTableRowsInserted: New rows added
• fireTableRowsDeleted: Deleted row
• fireTableStructureChanged: Invalidate structure and table (including data)

Editors and Renderers 

• Each cell in a table is ! a different component 
• Single Cell Renderer usually creates all cells that are that type of data. 
• Boolean: JCheckBox (check mark if true) 
• Number: JTextField (right aligned) 
• Double/Float: JTextField (but using NumberFormat from Java APIs). 
• Date: JTextField (rendered by a DateFormat) 
• ImageIcon: Centered JLabel 
• Object: JLabel with string's value. 

Tool Tips for Cells

• By default, it depends on the cell renderer (we can override JTable implement of getToolTipText(Mouse event)
• Override the getToolTipText(MouseEvent e) located in the java tutorials 
• To get the value of one cell, the method is getValueAt (row index, column index); 

Specifying Tool Tips for Table Headers

• For all headers: .getTableHeader().setToolTipText("Enter text here") will make this the default for all table headings
• Customization
• Create an array of what you want the tool tip headings to be. 
• When you create the JTable, use code from tutorials

Sorting 

• Easiest Way: .setAutoCreateRowSorter(true); 
• More control over sorting: Declare a TableRowSorter just for the table. 
• TableRowSorter looks at rows in the following order: 
1. Checks to see if the programmer has invoked a comparator..and if they have, then to defaultly use that one. 
2. Returns String.class: Checks to see if they are strings (and if they are, sorts it based on the "locale") 
3. Returns Comparable.class: Sorts string representations based on locale. 
4. If a string converter has been used to convert it into a different type, sort the string "mutant" 
5. If none of the above, sort by toString. 

Using a ComboBox Inside The Table 

• Just create a ComboBox, and to add things, there is an addItem class. 

Validating User Entered Text

• Default
• Error Checking is free for everything but String and Object. This should be good enough, though. 
• Error ends up being just a side effect of attempting to convert that object into something else. 
• The text turns red and you cannot move anywhere.
• Customization
• JFormattedTextField
•