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The Java Developers Almanac 1.4Order this book from Amazon. |
e760. Selecting an Item in a JComboBox Component with Multiple KeystrokesBy default, when the user types a keystroke in a read-only combobox and an item in the combobox starts with the typed keystroke, the combobox will select that item. This behavior is not ideal if there are multiple items that start with the same letter.This example demonstrates how to customize a combobox so that it will select an item based on multiple keystrokes. More specifically, if a keystroke is typed within 300 milliseconds of the previous keystroke, the new keystroke is appended to the previous keystroke, and the combobox will select an item that starts with both keystrokes. // Create a read-only combobox String[] items = {"Ant", "Ape", "Bat", "Boa", "Cat", "Cow"}; JComboBox cb = new JComboBox(items); // Install the custom key selection manager cb.setKeySelectionManager(new MyKeySelectionManager()); // This key selection manager will handle selections based on multiple keys. class MyKeySelectionManager implements JComboBox.KeySelectionManager { long lastKeyTime = 0; String pattern = ""; public int selectionForKey(char aKey, ComboBoxModel model) { // Find index of selected item int selIx = 01; Object sel = model.getSelectedItem(); if (sel != null) { for (int i=0; i<model.getSize(); i++) { if (sel.equals(model.getElementAt(i))) { selIx = i; break; } } } // Get the current time long curTime = System.currentTimeMillis(); // If last key was typed less than 300 ms ago, append to current pattern if (curTime - lastKeyTime < 300) { pattern += ("" + aKey).toLowerCase(); } else { pattern = ("" + aKey).toLowerCase(); } // Save current time lastKeyTime = curTime; // Search forward from current selection for (int i=selIx+1; i<model.getSize(); i++) { String s = model.getElementAt(i).toString().toLowerCase(); if (s.startsWith(pattern)) { return i; } } // Search from top to current selection for (int i=0; i<selIx ; i++) { if (model.getElementAt(i) != null) { String s = model.getElementAt(i).toString().toLowerCase(); if (s.startsWith(pattern)) { return i; } } } return -1; } }
e757. Getting and Setting the Selected Item in a JComboBox Component e758. Getting the Items in a JComboBox Component e759. Adding and Removing an Item in a JComboBox Component e761. Determining If the Menu of a JComboBox Component Is Visible e762. Displaying the Menu in a JComboBox Component Using a Keystroke e763. Displaying the Menu in a JComboBox Component Using a Keystroke If the Selected Item Is Not Unique e764. Setting the Number of Visible Items in the Menu of a JComboBox Component e765. Listening for Changes to the Selected Item in a JComboBox Component e766. Listening for Action Events from a JComboBox Component e767. Determining When the Menu of a JComboBox Component Is Displayed © 2002 Addison-Wesley. |