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Articles on Trending Technologies
Technical articles with clear explanations and examples
How 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 MoreWhat is "Argument-Dependent Lookup" ("Koenig Lookup") in C++?
Argument-dependent lookup(ADL) is a protocol for looking up unqualified function names in function-call expressions.These function call expressions include implicit function calls to overloaded operators.The function names are looked up in the namespaces of their arguments in addition to the scopes and namespaces considered by the usual unqualified name lookup. Argument-dependent lookup makes it possible to use operators defined in a different namespace. Examplenamespace MyNamespace{ class A {}; void f( A &a, int i) {} } int main() { MyNamespace::A a; f( a, 0 ); //calls MyNamespace::f }The lookup of a function call to f was dependent ...
Read MoreRead a character from standard input without waiting for a newline in C++
A portable solution doesn't exist for doing this. On windows, you can use the getch() function from the conio(Console I/O) library to get characters pressed.example#include #include using namespace std; int main() { char c; while(1){ // infinite loop c = getch(); cout
Read MoreSorting a vector of custom objects using C++ STL
You can sort a vector of custom objects using the C++ STL function std::sort. The sort function has an overloaded form that takes as arguments first, last, comparator. The first and last are iterators to first and last elements of the container. The comparator is a predicate function that can be used to tell how to sort the container. example#include #include #include using namespace std; struct MyStruct { int key; string data; MyStruct(int key, string data) { this -> key = key; this -> data = data; } }; int ...
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 MoreC++ Standards Support in GCC
GCC supports different dialects of C++, corresponding to the multiple published ISO standards. Which standard it implements can be selected using the -std= command-line option.C++98 − GCC has full support for the 1998 C++ standard as modified in 2003 and renamed to C++03 and some later defect reports.C++11 − GCC 4.8.1 was the first complete implementation of the 2011 C++ standard, previously known as C++0x.C++14 − GCC has full support for the latest revision of the C++ standard, which was published in 2014.C++17 − GCC has experimental support for the next revision of the C++ standard, which is expected to ...
Read MoreWhat are Aggregates and PODs in C++?
POD is an acronym in C++ that means plain old data. It is a class/struct that ONLY has member variables and no methods, constructors, destructors, virtual functions, etc. For example, Example#include using namespace std; // POD struct MyStruct { int key; string data; }; int main() { struct MyStruct s; s.key = 1; s.data = "hello"; return 0; }The struct MyStruct has no user defined ctor, dtor, etc and hence is a POD.An aggregate is an array or a class with no user-declared constructors, no private or protected non-static data members, no base ...
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