Advanced Java Programming - Swing Components

The javax.swing package contains all the Swing components, which provide a more modern and flexible user interface (UI) than the older Abstract Window Toolkit (AWT).

The AbstractButton class is the superclass for all Swing buttons, including JButton, JRadioButton, and JCheckBox. It provides common functionality for buttons, such as handling clicks and setting text.

The JLabel component in Swing supports various alignment options, including TOP, LEFT, CENTER, and TRAILING. However, it does not support an alignment option called LEADING.

The alignment constants for JLabel are defined in the SwingConstants interface. This interface provides common constants for various Swing components, including alignment.

To set an icon for a JLabel, you use the setIcon() method. The setIcon() method takes an instance of the Icon interface as its argument. The Icon interface is implemented by various classes that represent different types of icons, such as image files.

The JTextField class is responsible for text fields in Swing. It's a subclass of JTextComponent, which provides common functionality for text components.

The setColumns() method is used to specify the number of columns for a JTextField. This determines the width of the text field.

The getText() method of the JButton class returns a String representing the text displayed on the button. So the return type is String.

To assign both text and an icon to a JButton, you can use the setText() and setIcon() methods respectively. You can set them in the constructor, but separating them allows for flexibility.

When a JButton is pushed, it generates an ActionEvent. This event signifies that the button has been clicked or pressed.

JCheckBox generates an ItemEvent when clicked, signifying a change in its selection state.

JRadioButton is a class specifically designed for creating radio buttons.

ButtonGroup groups radio buttons together, ensuring only one can be selected at a time.

The JComboBox constructor can be used to add an entire Vector of objects to a JComboBox.

The setEditable(false) method prevents the drop-down list of a JComboBox from being editable.

The addTab() method is used for defining tabs within a tabbed pane.

The scroll bar constants for scroll panes are defined in the ScrollPaneConstants class.

The HORIZONTAL_SCROLLBAR_ALWAYS constant ensures that the horizontal scroll bar is always visible.

JScrollPane is a direct subclass of JComponent. It provides scrolling capabilities for its content.

Arrays of objects can be directly added to a JTree using its add( ) method.

The getPathForLocation() method translates a mouse click on a specific point of a JTree to a tree path, representing the selected node's hierarchy.

The TreeNode represents a single node within a JTree. It holds data and references to its children.

The TreeExpansionEvent class is defined in the javax.swing.event package, indicating that a tree node has been expanded or collapsed.

The TreeExpansionListener interface provides the treeExpanded() and treeCollapsed() methods to handle events when a tree node is expanded or collapsed.

You can create a JTree with a Vector as data by passing it to the JTree constructor. There's no specific method like addElement or addVector for Vectors.

The JTree constructor requires a data array, representing the tree nodes, as a parameter.

The getPathForLocation() method is used to translate a mouse click on a specific point of the tree to a tree path. This path represents the selected node's hierarchy within the tree. So, option (c) is the correct answer.

The TreeNode is a class because it encapsulates data and behavior related to a single node in a JTree. It provides methods for accessing parent, children, data, and related operations.

The TreeExpansionEvent class is defined in the javax.swing.event package, indicating when a tree node has been expanded or collapsed. It provides information about the event, including the affected node and the expansion state.

The TreeExpansionListener interface provides two useful methods: treeExpanded() and treeCollapsed(). These methods are called when a tree node is expanded or collapsed, respectively.