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Articles by raja
Page 35 of 38
How 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 ...
Read MoreHow to call an interface method in Java?
In order to call an interface method from a java program, the program must instantiate the interface implementation program. A method can then be called using the implementation object.Examplepublic interface InterfaceDemo{ default public void displayNameDefault(String name){ System.out.println("Your name is : " + name); } public void displayName(String name); public void displayNameAndDesignation(String name, String designation); }The above interface defines three methods for displaying a name and optionally a job title. One method is a default method that contains implementation logic. The remaining two methods do not include implementation logic.public class InterfaceDemoImpl ...
Read MoreHow to set Temporary and Permanent Paths in Java?
There are two ways to set the path in java, First is Temporary Path and second is Permanent Path.Setting Temporary PathOpen command prompt in WindowsCopy the path of jdk/bin directory where java located (C:\Program Files\Java\jdk_version\bin)Write in the command prompt: SET PATH=C:\Program Files\Java\jdk_version\bin and hit enter command.Setting Permanent PathGo to My Computer ---> Right Click on it ---> Advanced System Settings ---> Advanced Tab ---> Click on Environment VariablesClick on New tab of User variables, assign value JAVA_HOME to Variable Namejava\jdk_version\bin path (copied path) to Variable Value and click on OK ButtonFinally, click on OK button.
Read MoreHow can we implement a moving text using a JLabel in Java?
A JLabel is a subclass of JComponent class and an object of JLabel provides text instructions or information on a GUI. A JLabel can display a single line of read-only text, an image or both text and an image. A JLabel can explicitly generate a PropertyChangeListener interface. We can also implement a moving text in a JLabel by using a Timer class, it can set a timer with speed(in milliseconds) and this as an argument.Exampleimport java.awt.*; import java.awt.event.*; import java.util.*; import javax.swing.*; import javax.swing.Timer; public class MovingTextLabel extends JFrame implements ActionListener { private JLabel label; public MovingTextLabel() { setTitle("MovingTextLabel"); label= new JLabel(" ...
Read MoreHow can we set the background/foreground color for individual column of a JTable in Java?
A JTable is a subclass of JComponent class for displaying complex data structures. A JTable component 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, RowSorterListener interfaces. We can change the background and foreground color for each column of a JTable by customizing the DefaultTableCellRenderer class and it has only one method getTableCellRendererComponent() to implement it.Exampleimport java.awt.*; import javax.swing.*; import javax.swing.table.*; public class JTableColumnColorTest extends JFrame { private JTable table; private TableColumn tColumn; public JTableColumnColorTest() { setTitle("JTableColumnColor Test"); table = ...
Read MoreHow can we add/insert a JButton to JTable cell 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. We can add or insert a JButton to JTable cell by customizing the code either in DefaultTableModel or AbstractTableModel and we can also customize the code by implementing TableCellRenderer interface and need to override getTableCellRendererComponent() method.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.table.*; public class JTableButtonTest extends JFrame { private JTable table; private JScrollPane scrollPane; public JTableButtonTest() { ...
Read MoreHow to implement the search functionality of a JTable in Java?
A JTable is a subclass of JComponent for displaying complex data structures. A JTable component 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, RowSorterListener interfaces. We can implement the search functionality of a JTable by input a string in the JTextField, it can search for a string available in a JTable. If the string matches it can only display the corresponding value in a JTable. We can use the DocumentListener interface of a JTextField to implement it.Exampleimport java.awt.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.table.*; public ...
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