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Java Articles
Page 351 of 450
How to implement the mouse right-click on each node of JTree in Java?
A JTree is a subclass of JComponent class that can be used to display the data with the hierarchical properties by adding nodes to nodes and keeps the concept of parent and child node. Each element in the tree becomes a node. The nodes are expandable and collapsible. We can implement the mouse right-click on each node of a JTree using the mouseReleased() method of MouseAdapter class and need to call show() method of JPopupMenu class to show the popup menu on the tree node.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.tree.*; public class JTreeRightClickTest extends JFrame { ...
Read MoreHow to display "No records available" text in a JTable in Java?
A JTable is a subclass of JComponent class and it can be used to create a table with information displayed in multiple rows and columns. When a value is selected from a JTable, a TableModelEvent is generated, which is handled by implementing a TableModelListener interface.In the below program, we can display "No records available" text if the rows are not available in a JTable.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.table.*; public class NoRecordTableTest extends JFrame { private JPanel panel; private JTable table; private JScrollPane scrollPane; public NoRecordTableTest() { panel = new JPanel(); panel.setLayout(new BorderLayout()); ...
Read MoreHow to restrict the number of digits inside JPasswordField in Java?
A JPasswordField is a subclass of JTextField and each character entered in a JPasswordField can be replaced by an echo character. This allows confidential input for passwords. The important methods of JPasswordField are getPassword(), getText(), getAccessibleContext() and etc. By default, we can enter any number of digits inside JPasswordField. If we want to restrict the digits entered by a user by implementing a DocumentFilter class and need to override the replace() method.Syntaxpublic void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationExceptionExampleimport java.awt.*; import java.awt.*; import javax.swing.*; import javax.swing.text.*; public class JPasswordFieldDigitLimitTest extends JFrame { ...
Read MoreHow can we add different font style items to JList in Java?
A JList is a subclass of JComponent class and it can be used to display a list of objects that allows the user to select one or more items. A JList can generate a ListSelectiionListener interface and need to implement the abstract method valueChanged(). A DefaultListModel class provides a simple implementation of a list model, which can be used to manage items displayed by a JList control. We can add the items to a JList using the addElement() method of the DefaultListModel class, we can also add items with different fonts to JList using HTML tags like for bold ...
Read MoreHow can we implement transparent JDialog in Java?
A JDialog is a subclass of Dialog class and it does not hold minimize and maximize buttons at the top right corner of the window. There are two types of dialog boxes namely, modal and non-modal. The default layout for a dialog box is BorderLayout.In the below program, we can implement a transparent JDialog by customizing the AlphaContainer class and override the paintComponent() method.Exampleimport java.awt.*; import javax.swing.*; public class TransparentDialog { public static void main (String[] args) { JDialog dialog = new JDialog(); dialog.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); ...
Read MoreHow to select different cells of a JTable programmatically in Java?
A JTable is a subclass of JComponent class and it can be used to create a table with information displayed in multiple rows and columns. When a value is selected from a JTable, a TableModelEvent is generated, which is handled by implementing a TableModelListener interface.In general, a user can select the rows and columns manually in a JTable, we can also select different cells of a JTable programmatically using setRowSelectionInterval() and setColumnSelectionInterval() methods of JTable class.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class JTableCellSelectionTest extends JFrame { private JTable table; public JTableCellSelectionTest() { ...
Read MoreHow to detect the value change of a JSlider in Java?
A JSlider is a subclass of JComponent class and it is similar to scroll bar which allows the user to select a numeric value from a specified range of integer values. A JSlider has a knob which can slide on a range of values and can be used to select a particular value. and it can generate a ChangeListener interface.We can detect the value changed when the slider is moved horizontally using the Graphics2D class and override paint() method.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; public class ValueChangeJSliderTest extends JFrame { private JSlider slider; ...
Read MoreHow can we detect the double click events of a JTable row in Java?
A JTable is a subclass of JComponent for displaying complex data structures. A JTable can follow the Model View Controller (MVC) design pattern for displaying the data in rows and columns. A JTable can generate TableModelListener, TableColumnModelListener, ListSelectionListener, CellEditorListener and RowSorterListener interfaces. We can detect the double click events of a JTable by using a MouseAdapter class or MouseListener interface. We can set the getClickCount() value to '2' of a MouseEvent class for detecting the double click events of a JTable.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.table.*; public final class DoublClickJTableRowTest extends JFrame { private JTable table; private JScrollPane scrollPane; public DoublClickJTableRowTest() { ...
Read MoreWhat is the importance of JViewport class in Java?
JViewportA 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.setViewPosition() method.A JViewport class supports logical scrolling, that is a kind of scrolling in which view coordinates are not pixels.To support a logical scrolling, JViewport defines a small set of methods that can be used to define the geometry of a viewport and a view. By default, these methods just report the pixel dimensions of the viewport and view.Exampleimport java.awt.*; import javax.swing.*; public class JViewportTest extends JFrame { public JViewportTest() { setTitle("JViewport Test"); ...
Read MoreWhat is the importance of a SwingWorker class in Java?
A SwingWorker class enables us to perform an asynchronous task in a worker thread (such as a long-running task) then update Swing components from the Event Dispatch Thread (EDT) based on the task results. It was introduced in Java 1.6 Version.SwingWorker classThe java.swing.SwingWorker class is a task worker, which performs time-consuming tasks in the background.A SwingWorker instance interacts with 3 threads, Current thread, the Worker thread, and the Event Dispatch thread(EDT).The Current thread calls the execute() method to kick off the task to the background and returns immediately.The Worker thread executes our own version of the doInBackground() method continuously in the background.The Event Dispatch Thread (EDT) wakes up from time to ...
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