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Java™
by example!
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How do I create a JTable with a TableModel?
A JTable can be passed the values the table should contain during construction, using a 2d array or a Vector. Creating a table with these constructors has some restrictions, like all data elements are rendered as String values or all cell elements are editable. To be more flexible, you can create your own custom TableModel that basically encapsulates the table data and provides some semantic knowledge about the data to be able to render it with an appropriate visual component. For example, you may wish to get the table values from a database as they become available or you might want to render a JProgressBar inside a table cell. Your custom table model should implement the interface TableModel, but you could simply extend from AbstractTableModel (a standard JDK class that implements TableModel) and override its methods.
The following example will create a simple table model that contains data about wines. The table is not editable but rows can be added by calling the method addWine to the model. Notice that this method contains a call to fireTableRowsInserted to tell the view to render the added row. Internally, the model uses a Vector to hold the data. The following API methods were implemented:
- getColumnCount: called by the view to determine how many columns there are. The column names (headers) are hardcoded in an array. Return the length of this array.
- getRowCount: called by the view to determine how many rows there are. As the vector contains our data, we return the size of the vector.
- getColumnName: called by the view to render the column headers. Returns the element in our hardcoded header array.
- getColumnClass: called by the view to determine what renderer to use for the specified column index. In the superclass, AbstractTableModel, this method returns Object.class, meaning it will treat and render all cells the same (as Objects, the toString() method is called on them when rendering). However, we'd like our member variable inStock to be rendered as a CheckBox instead of "true" or "false". Therefore we return the Class of the column (hardcoded in the array columnClasses). This is enough for the view to know it should render column 4 as a JCheckBox instead of a JLabel. The data types Boolean, Number, ImageIcon and Object are recognized automatically and the view will use an appropriate cell renderer for them. Check out other questions in this category on how to create your own renderers eg. JProgressBar.
- getValueAt: called by the view to determine a value at a particular row and column. From the row, we can get the Wine element out of our vector. The column determines what method to call on that object.
- isCellEditable: called by the view to determine if a cell is editable or not. We return false in all cases.
Main.java:
Further Information
Author of answer: Joris Van den Bogaert
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