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Programming Articles
Page 2460 of 2547
Preventing Object Copy in C++
In C++, when classes are created, we can copy it using some copy constructor or assignment operator. In this section we will see, how to prevent object copy of a class in C++. To prevent object copy, we can follow some rules. These are like below.1. Creating private copy constructor and private assignment operator.Example#include using namespace std; class MyClass { int x; public: MyClass() { //non-parameterized constructor } MyClass(int y): x(y) { } private: MyClass(const MyClass& obj) ...
Read MoreWhat is the most effective way for float and double comparison in C/C++?
Here we will see how to compare two floating point data or two double data using C or C++. The floating point / double comparison is not similar to the integer comparison.To compare two floating point or double values, we have to consider the precision in to the comparison. For example, if two numbers are 3.1428 and 3.1415, then they are same up to the precision 0.01, but after that, like 0.001 they are not same.To compare using this criteria, we will find the absolute value after subtracting one floating point number from another, then check whether the result is ...
Read MoreJava Connection The setClientInfo() method with example
The setClientInfo() method of the Connection interface sets values to the client info properties of the current connection object.ParametersThis method accepts a Properties object as a parameter.con.setClientInfo(properties);To set values to the client info properties file.Register the driver using the registerDriver() method of the DriverManager class as −//Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver());Get the connection using the getConnection() method of the DriverManager class as −//Getting the connection String url = "jdbc:mysql://localhost/mydatabase"; Connection con = DriverManager.getConnection(url, "root", "password");Create a properties object as −Properties properties = new Properties();Add the required key-value pairs to the above created Properties object as −properties.put("user_name", "new_user"); properties.put("password", "password");Set the above created ...
Read MoreHow to highlight multiple rows in a sequence in a table with Java Swing?
To highlight multiple rows in a table, you can use the addRowSelectionInterval() method. At first create a table −DefaultTableModel tableModel = new DefaultTableModel(); JTable table = new JTable(tableModel);Add some columns −tableModel.addColumn("Language/ Technology"); tableModel.addColumn("Text Tutorial"); tableModel.addColumn("Video Tutorial"); tableModel.addColumn("Views");Now, add rows to the table −tableModel.addRow(new Object[] { "NodeJS", "No", "Yes", "2350"}); tableModel.addRow(new Object[] { "MVC", "Yes", "No", "1500"}); tableModel.addRow(new Object[] { "ASP.NET", "Yes", "Yes", "3400"}); tableModel.addRow(new Object[] { "F#", "Yes", "No", "7890"}); tableModel.addRow(new Object[] { "Blockchain", "Yes", "No", "10600"}); tableModel.addRow(new Object[] { "SharePoint", "Yes", "Yes", "4900"});Highlight multiple rows by adding interval of rows from both ends. Set interval (index) for both the ...
Read MoreMap to create new value from int array in Java
Let’s say the following is our int array elements:10, 50, 100, 200, 250, 300, 400, 500Here, we are mapping and creating a new value by incrementing each int element with 1:Arrays.stream(new int[] {10, 50, 100, 200, 250, 300, 400, 500}).map(val -> val + 1)Now find the average:Arrays.stream(new int[] {10, 50, 100, 200, 250, 300, 400, 500}).map(val -> val + 1).average()The following is an example to Map and create new value from int array:Exampleimport java.util.Arrays; public class Demo { public static void main(String[] args) throws Exception { Arrays.stream(new int[] {10, 50, 100, 200, 250, 300, 400, 500}).map(val -> val + 1).average() .ifPresent(System.out::println); } }Output227.25
Read MoreWhat is the difference between const int*, const int * const, and int const *?
Here we will see some different types of variable declaration based on integer pointers integer constants and the integer constant pointers.To determine them we will use the Clockwise/Spiral Rule. By discussing the terms, we can understand the rules also.The const int *. This is used to tell the compiler that this is a pointer type variable, and this can store address of some constant int. The Clock rule is saying like this −Now the another one is const int * const. This is used to denote that this is one constant pointer variable, which can store the address of another ...
Read MoreHow to set the background color of a single tab in a JTabbedPane Container with Java?
To set the background color of a single tab, use the setBackgroundAt() method. This gives an option to mention the index and the color. The index here is the index of the specific tab you want to color.Let us first create a JTabbedPane −JTabbedPane tabbedPane = new JTabbedPane();Now, set the background color for one of the tabs with index 2 −tabbedPane.setBackgroundAt(2, Color.RED);The following is an example to set the background color of a single tab in a JTabbedPane container −Examplepackage my; import javax.swing.*; import java.awt.*; public class SwingDemo { public static void main(String args[]) { JFrame ...
Read MoreWhat is difference between a pointer and reference parameter in C++?
PointersPointer variables are used to store the address of variable.SyntaxType *pointer;InitializationType *pointer; Pointer=variable name;ReferencesWhen a parameter is declared as reference, it becomes an alternative name for an existing parameter.SyntaxType &newname=existing name;InitializationType &pointer; Pointer=variable name;The main differences between pointers and reference parameters are −References are used to refer an existing variable in another name whereas pointers are used to store address of variable.References cannot have a null value assigned but pointer can.A reference variable can be referenced by pass by value whereas a pointer can be referenced by pass by reference.A reference must be initialized on declaration while it is not ...
Read MoreWhat is the effect of extern "C" in C++?
The extern “C” keyword is used to make a function name in C++ have the C linkage. In this case the compiler does not mangle the function. Let us see what is the mangling in C++ first, then we can discuss about the extern “C” keyword.In C++ we can use the function overloading feature. Using this feature, we can create functions with same name. The only difference is the type of the arguments, and the number of arguments. The return type is not considered here. Now the question comes how the C++ distinguishes overloaded functions in object code?In the object ...
Read MoreHow to add empty border to JPanel in Java?
To add empty border, use the createEmtyBorder() method. Let us first create a new JLabel −JLabel label; label = new JLabel("Label with empty border!");Now, set empty border using the setBorder() method −label.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));The following is an example to add empty border to JPanel −Examplepackage my; import javax.swing.BorderFactory; import java.awt.Font; import javax.swing.JFrame; import javax.swing.JLabel; public class SwingDemo { public static void main(String[] args) throws Exception { JFrame frame = new JFrame("Demo"); JLabel label; label = new JLabel("Label with empty border!"); label.setFont(new Font("Verdana", Font.PLAIN, 16)); ...
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