What is a JComboBox?
JComboBox is a part of Java Swing package. JComboBox inherits JComponent class . JComboBox shows a popup menu that shows a list and the user can select a option from that specified list . JComboBox can be editable or read- only depending on the choice of the programmer .
How do you change the size of a JComboBox?
You can control the display by using: comboBox. setPrototypeDisplayValue(“text here”); You might also consider using the Combo Box Popup to control the popup size.
Which is the superclass for JComboBox?
Other methods you are most likely to invoke on a JComboBox object are those it inherits from its superclasses, such as setPreferredSize . See The JComponent API for tables of commonly used inherited methods.
Which method is used to add items in JComboBox?
Commonly used Methods:
| Methods | Description |
|---|---|
| void addItem(Object anObject) | It is used to add an item to the item list. |
| void removeItem(Object anObject) | It is used to delete an item to the item list. |
| void removeAllItems() | It is used to remove all the items from the list. |
Which JComboBox method makes the item at the specified index the selected item?
Method Summary
| Modifier and Type | Method and Description |
|---|---|
| ComboBoxEditor | getEditor() Returns the editor used to paint and edit the selected item in the JComboBox field. |
| E | getItemAt(int index) Returns the list item at the specified index. |
| int | getItemCount() Returns the number of items in the list. |
How remove all items from JComboBox in Java?
this. combo. removeAllItems(); to remove all the items in JComboBox.
Which method can a program use to set the selected choice in a JComboBox?
Which method can aprogram use to set the selected choice in a JComboBox? The selection can only be set through the GUI by the user.
What is JViewport?
A JViewport class defines the basic scrolling model and it is designed to support both logical scrolling and pixel-based scrolling. The viewport’s child called the view is scrolled by calling JViewport.
What is DefaultMutableTreeNode?
A DefaultMutableTreeNode is a general-purpose node in a tree data structure. A node with no parent is the root of its tree; a node with no children is a leaf.
Why is setpreferredsize never called in jcombobox?
JComboBox.setPreferredSize () is never explicitly called, so I assume you get better results from telling the layout manager the preferred size and re-size properties, rather than telling the JComboBox and hoping the layout manager reads those properties behind the scenes.
How is the size of a combo box calculated?
If a prototype display value is specified, the preferred size of the combo box is calculated by configuring the renderer with the prototype display value and obtaining its preferred size. Specifying the preferred display value is often useful when the combo box will be displaying large amounts of data.
Do you need a custom renderer for a combo box?
To put anything else into a combo box or to customize how the items in a combo box look, you need to write a custom renderer. An editable combo box would also need a custom editor. Refer to Providing a Custom Renderer for information and an example. The preceding code registers an action listener on the combo box.
Why are combo boxes not editable in Java?
This is necessary because, by default, a combo box is not editable. This particular example allows editing on the combo box because its menu does not provide all possible date formatting patterns, just shortcuts to frequently used patterns.