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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to prevent resizing columns in a JTable
To prevent resizing columns, use the method setResizingAllowed(). Here, we will set setResizingAllowed() to false for table header to disallow resizing of columns from header −table.getTableHeader().setResizingAllowed(false);Let us first see an example wherein we can easily resize columns in a table by resizing the table column header −Examplepackage my; import java.awt.Color; import java.awt.Font; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.table.DefaultTableModel; public class SwingDemo { public static void main(String[] argv) throws Exception { DefaultTableModel tableModel = new DefaultTableModel(); JTable table = new JTable(tableModel); tableModel.addColumn("Language/ Technology"); tableModel.addColumn("Text Tutorial"); ...
Read MoreWhat is consensus protocol in Block Chain?
Consensus protocol is one of the most important aspects that makes the Block chain network a fool proof system. It is the revolutionary protocol that makes the Block chain network an irrefutable system where the majority of devices (nodes) connected to the network agree on each and every transaction. This prevents exploitation of the system as more than 51% consensus is required to create a new block. It is the core of the Block Chain which makes it certain that the information stored on the Block Chain is accurate and honest.The very core of the Nakamoto’s Block chain consensus protocol ...
Read MoreHow to insert/store JSON array into a database using JDBC?
A Json array is an ordered collection of values that are enclosed in square brackets i.e. it begins with ‘[’ and ends with ‘]’. The values in the arrays are separated by ‘, ’ (comma).Sample JSON array{ "books": [ Java, JavaFX, Hbase, Cassandra, WebGL, JOGL] }The json-simple is a light weight library which is used to process JSON objects. Using this you can read or, write the contents of a JSON document using Java program.JSON-Simple maven dependencyFollowing is the maven dependency for the JSON-simple library − com.googlecode.json-simple json-simple ...
Read MoreMiddle of three using minimum comparisons in C++
In this section, we will see how to find the middle of three given values by comparing them. So if three numbers are given like (10, 30, 20), then it will find 20 as this is the middle element. Let us see the algorithm first, then we will implement that algorithm into C++ code.Algorithmmiddle_of_three(a, b, c): Input: Three numbers a, b and c Output: The middle of these three Begin if a > b, then if b > c, then return b else if a > c, then ...
Read MoreHow to get the list of all databases using JDBC?
You can get the list of databases in MySQL using the SHOW DATABASES query.show databases;Following JDBC program retrieves the list of databases by executing the show databases query.Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class ShowDatabasesExample { public static void main(String args[]) throws Exception { //Registering the Driver DriverManager.registerDriver(new com.mysql.jdbc.Driver()); //Getting the connection String mysqlUrl = "jdbc:mysql://localhost/mydatabase"; Connection con = DriverManager.getConnection(mysqlUrl, "root", "password"); System.out.println("Connection established......"); //Creating a Statement object Statement stmt = con.createStatement(); ...
Read MoreWhat is the difference between a destructor and a free function in C++?
Here we will see what are the differences between destructor and the free() functions in C++. The destructor is used to perform some action, just before the object is destroyed. This action may not freeing up the memory, but can do some simple action such as displaying one message on screen.The free() function is used in C, in C++, we can do the same thing using delete keyword also. When the object is deleted using free() or delete, the destructor is invoked. The destructor function takes no argument and returns nothing. This function is called when free or delete is ...
Read MoreHow to get all the column names from a ResultSet using JDBC
You can get the name of a particular column using the getColumnName() method of the ResultSetMetadata interface.This method accepts an integer value representing the index of a column and returns a String value representing the name of the specified column.Let us create a table with name MyPlayers in MySQL database using CREATE statement as shown below −CREATE TABLE MyPlayers( ID INT, First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), PRIMARY KEY (ID) );Now, we will insert 7 records in MyPlayers table using INSERT statements −insert into MyPlayers values(1, 'Shikhar', 'Dhawan', DATE('1981-12-05'), 'Delhi', 'India'); insert into MyPlayers ...
Read MoreSet whether the row in the table model can be selected or deselected in Java?
We can set or disallow selection of row in the table using setRowSelectionAllowed().Let’s say the following is our table −DefaultTableModel tableModel = new DefaultTableModel(); JTable table = new JTable(tableModel);If you want to allow selection of row, then set the method to TRUE −table.setRowSelectionAllowed(true);If you want to disallow selection of row, then set the method to FALSE −table.setRowSelectionAllowed(false);We have disallowed selection of rows in the below example −Examplepackage my; import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.table.DefaultTableModel; public class SwingDemo { public static void main(String[] argv) throws Exception { DefaultTableModel tableModel = new DefaultTableModel(); ...
Read MoreJava ResultSetMetaData getColumnName() method with example
The getColumnName() method of the ResultSetMetaData (interface) retrieves and returns the name of the specified column in the current ResultSet object.This method accepts an integer value representing the index of a column and, returns a String value representing the name of the specified column.To get the ResultSetMetaData object, you need to −Register the Driver: Select the required database register the Driver class of the particular database using the registerDriver() method of the DriverManager class or, the forName() method of the class named Class.DriverManager.registerDriver(new com.mysql.jdbc.Driver());Get connection: Create a connection object by passing the URL of the database, username and password of a ...
Read MoreHow to set JAVA_HOME environment variables on Windows OS in Java?
Once you have installed JDK version on your windows machine, you have to set up Environment Variables.Please find below steps to set the java pathGo to My Computer ---> Right Click on it ---> Advanced System Settings ---> Advanced Tab ---> Click on Environment VariablesNow you have to alter the “Path” variable under system variables such that it contains a path to Java Environment. Select the path variable and click on the “Edit” buttonBy default, Java is installed in “C:\Program Files\Java\jre version\bin” in case you have changed the location of installation, then add that pathClick on OK button and now ...
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