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With JDK 7, we can create a translucent window using swing very easily. With following code, a JFrame can be made translucent.// Set the window to 55% opaque (45% translucent). frame.setOpacity(0.55f);ExampleSee the example below of a window with 55% translucency.import java.awt.GridBagLayout; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.SwingUtilities; public class Tester { public static void main(String[] args) { JFrame.setDefaultLookAndFeelDecorated(true); // Create the GUI on the event-dispatching thread SwingUtilities.invokeLater(new Runnable() { @Override public void ... Read More
A toast message is an alert which disappears with time automatically. With JDK 7, we can create a toast message similar to an alert on android very easily. Following are the steps needed to make a toast message.Make a rounded rectangle shaped frame. Add a component listener to frame and override the componentResized() to change the shape of the frame. This method recalculates the shape of the frame correctly whenever the window size is changed.frame.addComponentListener(new ComponentAdapter() { @Override public void componentResized(ComponentEvent e) { frame.setShape(new RoundRectangle2D.Double(0, 0, frame.getWidth(), frame.getHeight(), 20, 20)); } ... Read More
You can sleep for any period of time from one millisecond up to the lifetime of your computer. For example, the following program would sleep for 3 seconds −Example Live Demoimport java.util.*; public class SleepDemo { public static void main(String args[]) { try { System.out.println(new Date( ) + ""); Thread.sleep(5*60*10); System.out.println(new Date( ) + ""); } catch (Exception e) { System.out.println("Got an exception!"); } } }This will produce the following result −OutputSun May 03 18:04:41 GMT 2009 Sun May 03 18:04:51 GMT 2009
Swing API is a set of extensible GUI Components to ease the developer's life to create JAVA based Front End/GUI Applications. It is built on top of AWT API and acts as a replacement of AWT API since it has almost every control corresponding to AWT controls.Following example showcases a simple calculator application.import java.awt.BorderLayout; import java.awt.GridBagConstraints; import java.awt.GridBagLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JTextField; public class Calculator implements ActionListener { private static JTextField inputBox; Calculator(){} public static void main(String[] args) { createWindow(); } ... Read More
With JDK 7, we can create a shaped window using swing very easily. Following are the steps needed to make a shaped window. Add a component listener to frame and override the componentResized() to change the shape of the frame. This method recalculates the shape of the frame correctly whenever the window size is changed.frame.addComponentListener(new ComponentAdapter() { @Override public void componentResized(ComponentEvent e) { frame.setShape(new RoundRectangle2D.Double(0, 0, frame.getWidth(), frame.getHeight(), 20, 20)); } });ExampleSee the example below of a shaped window.import java.awt.Color; import java.awt.GridBagLayout; import java.awt.event.ComponentAdapter; import java.awt.event.ComponentEvent; import java.awt.geom.Ellipse2D; import java.awt.geom.RoundRectangle2D; import ... Read More
MySQL allows us to add a FOREIGN KEY constraint on more than one field in a table. The condition is that each Foreign Key in the child table must refer to the different parent table.ExampleSuppose we have a table ‘customer2’ which have a Primary Key constraint on the field ‘cust_unq_id’ as follows −mysql> describe customer2; +-------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+-------------+------+-----+---------+-------+ | cust_id | int(11) | YES | | NULL | | | First_name | ... Read More
We can remove composite PRIMARY KEY constraint from multiple columns of an existing table by using DROP keyword along with ALTER TABLE statement.ExampleSuppose we have a table ‘Room_allotment’ having a composite PRIMARY KEY constraint on columns ‘ID’ and ‘RoomNo’ as follows −mysql> describe room_allotment; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | id | int(11) | NO | PRI | 0 | | | Name | varchar(20) | NO | PRI | ... Read More
We can set PRIMARY KEY constraint on multiple columns of an existing table by using ADD keyword along with ALTER TABLE statement.ExampleSuppose we have a table ‘Room_allotment’ as follows −mysql> Create table Room_allotment(Id Int, Name Varchar(20), RoomNo Int); Query OK, 0 rows affected (0.20 sec) mysql> Describe Room_allotment; +--------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+-------+ | Id | int(11) | YES | | NULL | | | Name | varchar(20) | YES | | NULL ... Read More
Python doesn't have an equivalent of do-while loop as in C/C++ or Java. The essence of do-while loop is that the looping condition is verified at the end of looping body. This feature can be emulated by following Python code −Examplecondition=True x=0 while condition==True: x=x+1 print (x) if x>=5: condition=FalseOutputThe output is as follows −1 2 3 4 5
As we know the AUTO_INCREMENT column must have the PRIMARY KEY constraint on it also hence when we will try to drop PRIMARY KEY constraint from the AUTO_INCREMENT column the MySQL returns an error message regarding the incorrect table definition. The example below will demonstrate it −ExampleSuppose we have ‘Accounts’ table having the following description −mysql> Describe accounts; +--------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------+-------------+------+-----+---------+----------------+ | Sr | int(10) | NO | PRI | NULL | auto_increment | ... Read More