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Articles by raja
Page 34 of 38
How to define the naming conventions for JSON field names in Java?
The FieldNamingPolicy can be used to define a few standard naming conventions for JSON field names and it can be used in conjunction with GsonBuilder to configure a Gson instance to properly translate Java field names into the desired JSON field names. We can use the setFieldNamingPolicy() method of GsonBuilder to configure a specific naming policy strategy to an object's field during serialization and deserialization.Gson supports various field naming requirements with following field naming policiesFieldNamingPolicy.IDENTITY: It uses the exact same naming as the Java model when it serializes an object.FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES: It modifies a Java field name from its camel-cased form to a lower case field name where ...
Read MoreWhat is the use of underscore keyword in Java 9?
In earlier versions of Java, the underscore ("_") has used as an identifier or to create a variable name. Since Java 9, the underscore character is a reserved keyword and can't be used as an identifier or variable name. If we use a single underscore character as an identifier, the program fails to compile and throws a compile-time error because now it is a keyword and can't be used as a variable name in Java 9 or later versions.Examplepublic class UnderscoreKeywordTest { public static void main(String args[]) { int _ = ...
Read MoreHow to validate if JTable has an empty cell in Java?
A JTable is a subclass of JComponent class 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 will generate TableModelListener, TableColumnModelListener, ListSelectionListener, CellEditorListener and RowSorterListener interfaces.We can validate whether the JTable cell is empty or not by implementing the getValueAt() method of JTable class. If we click on the "Click Here" button, it will generate an action event and display a popup message like "Field is Empty" to the user.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.table.*; public class JTableEmptyValidateTest extends JFrame { ...
Read MoreHow can we filter a JTable in Java?
A JTable provides a very flexible possibility to create and display tables. The TableModel interface defines methods for objects that specify the contents of a table. The AbstractTableModel class is typically extended to provide a custom implementation of a model table. A JTable class provides the ability to edit tables using the method setCellEditor() allows an object of the TableCellEditor interface.We can filter a table using the setRowFilter() method of TableRowSorter class.Exampleimport java.awt.*; import java.awt.event.*; import java.util.regex.*; import javax.swing.*; import javax.swing.table.*; public class FilterTableTest extends JFrame { private JTable table; private TableModel model; ...
Read MoreHow 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() { ...
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