Swing/AWT/SWT :: What Are Parent And Child Components
Aug 11, 2014
I keep hearing these two term when it comes to painting in Swing, however, I'm not sure which is which. To my understanding is that the child components are the ones that already exist on screen (could be a JButton, JFrame, or custom painting) . and the parent components are the one to be added/drawn next. (hence, if we override the paintChildren() method when painting, the components that were already on the screen don't appear any more).
I keep hearing these two term when it comes to painting in Swing, however, I'm not sure which is which. To my understanding is that the child components are the ones that already exist on screen (could be a JButton, JFrame, or custom painting) . and the parent components are the one to be added/drawn next. (hence, if we override the paintChildren() method when painting, the components that were already on the screen don't appear any more) ....
I am very new to Java Swing. I have to create a TreeTable in Java Swing with a Parent Row having say 6 columns and its all child row having just 4 columns. like shown below
I have been working on a simple problem, but I am stuck. I am trying to learn parent and child classes and how they work. The program in broken into three classes; the DemoBook class that runs the various methods, the Book class that gathers information and displays it, and finally a child class of Book (called TextBook) that just gets one piece of data and then is suppossed to return that data back to Book. However, this is not working and I know I am missing something; I believe it has to do with Set and Get methods, but I am confused with how these work.
Java Code:
public class DemoBook { public static void main (String[] args) { Book aBook = new Book(); Textbook aText = new Textbook();
I am creating a commenting system for a side project of mine I'm building using AnuglarJS for the front-end and Spring MVC for the backend.
I am having difficulty coming up with an algorithm that will populate each comment object with a list of the comments that are responses/children of it.
The below code is what I have so far. The problem is is that it duplicates comments.
public List<Comment> getComments(int id) { MapSqlParameterSource params = new MapSqlParameterSource(); params.addValue("id", id); List<Comment> allComments = jdbc.query("select * from comments where debate_id=:id", params, new RowMapper<Comment>()
The company entity contains companyName, Sector and Segment columns. The mapping is 3 entities (Company, Sector, Segment) where Sector and Segment are used to create a company record. Sector has a OneToMany relationship with Segment and with Company. I put the Sector and Segment values into two select menus as use these to create a Sector and Segment reference for the Company table. I'm getting the following exception:
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (`testdummy`.`company`, CONSTRAINT `FK_COMPANY_FK_COMPANY_SECTORID` FOREIGN KEY (`FK_COMPANY_SECTORID`) REFERENCES `sectors` (`SECTORID`)) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
I'm thinking that the problem is that since the Segment entity is a child of Sector it must be entered through an instance of Sector. Because it's being entered as a separate value I'm getting this error. The problem is Segment is defined as a Set in the Sector entity and I can't figure out how to declare Segment as an instance using its parent entity (Sector).
My code is as follows, starting with the Sector entity:
@Entity @Table(name = "SECTORSNEW") public class SectorsNew { @Id @GeneratedValue(strategy = GenerationType.AUTO) private int sectorId; private String sectorName; @OneToMany(cascade = CascadeType.PERSIST)
Regarding the lifecycle of servlet , in headfirst servlet i can find :
You normally will NOT override the service() method, so the one from HttpServlet will run. The service() method figures out which HTTP method (GET, POST, etc.) is in the request, and invokes the matching doGet() or doPost() method. The doGet() and doPost() inside HttpServlet don’t do anything, so you have to override one or both. This thread dies (or is put back in a Container-managed pool) when service() completes.
How can I call the doGet method of the subclass from the superclass. i am not getting this .
I want to know is there any way we can call parent class method using child class object without using super keyword in class B in the following program like we can do in c++ by using scoop resolution operator
class A{ public void hello(){ System.out.println("hello"); } } class B extends A{ public void hello(){ //super.hello(); System.out.println("hello1");
I've a parent class with a argument constructor like below(a sample code)
public class Parent { Parent(String name) { System.out.println(name); } public static void main(String[] args) { } }
Also I've child.class which extends Parent.class as shown below,
public class child extends Parent { child(String name) { super(name); } }
Now, I want create/modify the constructor which is in child, by taking "int i" as an input instead of "String name". How can I do that? Run time I want to execute child constructor not a parent constructor.
Condition is: Without making any changes to the Parent class
I want to make an application and must use strategy pattern my idea is to create a super class in this case Movie Player and three sub classer and they'll komminesera with each other using strattegy pattern, one of the sub classes is Button Panel and I want to add it to Movie Player and it was to be its child,so how can I add the butt panel to Movie Player and it shall be its children?
I have a JPanel with vertical BoxLayout. It contains four components. I set the JPanel to LEFT_ALIGNMENT, which has no effect on its components. I set the first component to LEFT_ALIGNMENT, which has no effect. Only after I have set all four components to LEFT_ALIGNMENT do any of them align properly.
This suggests that it is impossible to have varying alignments in a container. They must all be the same alignment.
I accept that this is just the way things are: "Java works in mysterious ways." And I'm sure that it is possible to work around this limitation by stacking boxes that themselves have different internal alignments.
But I still wonder what in the world was going on in the minds of the Java developers. Is there a rational reason for this oddity?
This raises my most serious criticism of Swing: the hidden gotcha. Swing is a tangled mess of cross-connecting requirements that are impossible to divine by simple inspection of the documentation. If you want to use, say, a JRadioButton, it's not enough to study the documentation on JRadioButtons; you must also consult lots of documents for which there is no obvious connection to JRadioButton other than it being part of Swing.
I am trying to send a JPanel object to the server. While doing so I get the error -
java.io.NotSerializableException: javax.swing.filechooser.WindowsFileSystemView at java.io.ObjectOutputStream.writeObject0(Unknown Source) at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source) at java.io.ObjectOutputStream.writeSerialData(Unknown Source) at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
I have swing UI designed and I want the components to resize when the frame is manually resized. The design is as shown in the fig Project UI.jpg
The panel 4 and panel 5 will change their contents according to the list item clicked. Panel 4 just has text area but panel 5 a panel with numerous components as label, combo box, text field,check box will be present.Now if the frame resizes, I won't all the components to resize according to the frame size.
Let me explain by simplifying the GUI to a simple frame in which I have a JCheckbox and a JPanel mypanel.mypanel has a Textfield tf,JComboBox cmb as it's components.So now if I deselect the JCheckbox, all the components in the mypanel should be disabled. I used a code like:
but the components inside the panels are not disabled. In my actual program I have a large number of different kinds of components in mypanel.So disabling/enabling each of them on each actionPerformed of the mycheckbox will be laborious. Isn't there any way by which I can disable/enable the mypanel to disable/enable all the components in it?
I trying to replace original (and empty) JPanel in JFrame with my own made one, components does no appear right, when I pass the mouse first button appears:
My panel named panelIncomeInfo are not showing the components that I have added.
public class PayrollGUI { private JPanel panelIncomeInfo = new JPanel (); private JPanel panel = new JPanel (); private JPanel panelPayCheckInfo = new JPanel (); private JButton close = new JButton ("Close");
My JPanel when adding components to it will never make its self larger but it will make my components inside smaller even though I have set the minimum and preferred sizes for those components? I am using the GridBagLayout for my layout manager as I am trying to get used to it.
I wish to display a progress bar during a lengthy file translation process. When I created a ProgressBar class to do this and tested it with a short test program, it seemed to work fine. But when I add my ProgressBar class to a package containing various other classes, put that package in a jar file, and then execute the class using the progress bar from a menu in my main program, the frame of the progress bar shows up with the appropriate caption but the JLabel, JProgressBar, and JButton are not displayed. I have gone over my code numerous times and checked that the ProgressBar class constructor is getting the proper arguments.
// package gov.nasa.jpl.ephemeris; import java.awt.*; import java.awt.event.*; import javax.swing.*; /** * Progress bar with message text above the bar and a Cancel button below it */ public class ProgressBar extends JFrame { private boolean _cancelled = false; private JProgressBar _progressBar = null;
[Code] ....
I have also been wondering whether I need a separate instance of the border for each panel, or whether I can just create one instance and use it for all three panels.
I'm working on Ubuntu with resolution 1600*900; I used MigLayout to place the components of the application; but when I go with higher resolutions,components adjustment and alignment are not up to the mark.
I have quite a specific view for how I want my components layed out. No matter what I try I can get them to display how I want! I'm using three JPanels. There's a main panel that goes inside the tabbed pane. This main panel contains two other panels. The First panel is a gridbaglayout panel, with labels on the left column, and components on the right column. The second panel is underneath the second, and contains a label, and a button beneath it. THis uses a basic box layout, with one component per line. The label doesn't always appear (depends if a component is changed). With everything showing, this is how it looks so far:
However, I want the Labels on the left of the pane. The right hand column should be aligned horizontally and have more space from the labels. Ideally I'd like a gap between the last label/checkbox and the Note label.
This is my current code for the panel/s inside the tabbed pane window.
videoPanel = new JPanel(); applyVidBtn = new JButton("Apply Settings"); applyVidBtn.setVisible(false); warningLbl = new JLabel("Note. Applying these settings causes a program restart."); warningLbl.setVisible(false);
class Test3 { } class MySub extends Test3 { } class Test4{ public static void main(String args[]) { MySub m = new MySub(); } }
I learned that if a class and its parent class both have no constructors, the compiler is supposed to complain. When I compiled Test4, i got no errors. why did it give no errors?
