Parent-Child Commenting Algorithm
Sep 11, 2014
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>()
[Code] ....
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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).
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Jan 25, 2014
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();
[Code] .....
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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) ....
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Oct 31, 2014
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)
[code]....
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Mar 1, 2015
Does child class gets a copy of the methods and variables of parent class?
public class test1 {
public static void main(String a[]) {
Child c = new Child();
c.print();
[Code] ....
why is the output 1?
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May 28, 2014
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 .
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Feb 4, 2015
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");
[code]....
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Dec 2, 2005
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
Parent row:
-Column1-+-Column2-+-Column3-+-Column4-+-Column5-+-Column6-+
Child row:
--CloumnC1--+--CloumnC2--+--CloumnC3--+--CloumnC4--+
Can this be achieved using JSwing ?Also, Can I be able to Change the Column Headers Correspondingly when user clicks on Parent row and Child rows?
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Feb 7, 2014
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
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Mar 7, 2014
I've Parent and child(extends Parent) class To initialize the constructors, I'm injecting from google.juice#injector. Let me show the code,
Parent.class
public class Parent{
private Animal animal;
@inject
Parent(Animal animal){
this.animal = animal;
[code].....
When I do this, ClassCastException is happening. Why is it so? Is there any way to convert instance of parent to child instance.
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Mar 10, 2014
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?
I read this article : [URL] ....
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Mar 2, 2014
Are there any alternatives to JFrame that can be used as a parent Frame?
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Jan 29, 2014
I'm working on a program using GUI. My problem is that I'm reaching **1000 Line** and this is stressful because all my code are in one file. I'm not liking this. So I research the internet about Inheritance. However, what I know about Inheritance that Inherit everything in the parent class. However, when I try to use a variables in the child class to override it in the parent class I can't for example let say that I have in the parent class something like this:
JButton getButton = new JButton("Enter");
Now when I go to the child class. I want to Inherit and use this variable so I can use the ActionListener on the getButton and override for the parent class, but it's not working.
This is my code:
public class H_Store extends JFrame {
private String s ="Kinds: ";
private JButton calculateButton;
private JPanel mainPane;
private JPanel getProfitPanel;
private JTextField ground_M_QTextField;
[Code] ....
What I want to do exactly is to take the last code into another class or do something with it so I can use it in the Parent class, in other word any math calculation method or class I want them outside the Parent class. I mean this code :
private class CalcButtonListener implements ActionListener{
// vairbles for the ground Meat check box
private double total_GM;
private double weightPrice_1;
private String stringQ;
private String stringW;
private String stringP;
[Code] ....
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Apr 21, 2015
I have a requirement to read all the xml files from a parent folder and write in a spreadsheet(separate spreadsheet for each xml file)
I have written the below code in which xml and excel file name are hardcoded. The format of xml file is same.
package xmlexcel;
import org.apache.poi.hssf.usermodel.*;
import java.util.ArrayList;
import java.awt.List;
import java.io.*;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.SAXException;
[Code]...
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Jan 22, 2014
We created one web application which runs on tomcat 7.0.35 using spring mvc 3.0 . Its working perfectly on 32-bit windows machine in IE 8 on Windows 7 OS, when we tried to run this on 64-bit windows 2008 Server, jquery is not working. Also I populate data from Pop-up JSP to parent JSP, and it works 3/10 times only and does not work always.
We used the following jquery plugins in our project
jquery 1.8.3
jquery.ui.custom.1.9.2
jquery.ui.custom.min-1.9.
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Jan 1, 2015
I have the following objects:
User Object:
public class User implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(unique = true, nullable = false)
private int id;
@OneToMany(fetch = FetchType.EAGER, mappedBy = "user", cascade = CascadeType.ALL)
private List<UserReason> userReasons;
....
Code :
public List<UserReason> getUserReasons() {
return userReasons;
}
public void setUserReasons(List<UserReason> userReasons) {
this.userReasons = userReasons;
}
public UserReason addUserReason(UserReason userReason) {
if (userReasons == null) {
userReasons = new ArrayList<UserReason>();
[Code] ....
I want to be able to add userReason to the list, and that Hibernate will automatically update the reference between the parent & child object.
When using the above code, when trying to start the server, i'm getting the error message:
Repeated column in mapping for entity: com.commit.safebeyond.model.UserReason column: userId (should be mapped with insert="false" update="false")
Please notice that i mapped the userId in UserReasonPK with insertable = false, updatable = false.
If i change it, and add this on the User property in UserReason object, server is up, but when trying to insert new User I'm getting the following error:
Hibernate: insert into UserReasons (reasonId, userId) values (?, ?)
WARN 2015-01-01 13:25:17,488 [http-nio-8080-exec-2] org.hibernate.engine.jdbc.spi.SqlExceptionHelper - SQL Error: 1452, SQLState: 23000
ERROR 2015-01-01 13:25:17,488 [http-nio-8080-exec-2] org.hibernate.engine.jdbc.spi.SqlExceptionHelper - Cannot add or update a child row: a foreign key constraint fails (`SafeBeyond`.`UserReasons`, CONSTRAINT `FK_UserReasons_Users` FOREIGN KEY (`userId`) REFERENCES `Users` (`id`))
[Code] ....
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Aug 27, 2014
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?
MoviePlayer:
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import com.github.sarxos.webcam.WebcamPanel;
[code]....
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May 7, 2015
I can call a child method from a main method. If I have a parent called "Assessment", a child called "Quiz", and another child called "test". Can I instantiate an object like Assessment a = new test(); and call a method in test.
I know the method can be called if I instantiate the test t = new test() but that defeats the purpose of inheritance...
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Apr 4, 2014
i have created two(displaypanel & buttonpanel) main panels in a JFrame and many child panels,one of the panel is for holding buttons and displaypanel mainly swap child panel as directed from buttonpanel, but the problem arises i cannot navigate from child panel to another child panel,
as i have made a button on one of a child panel and from button panel i add the childpanel to displaypanel.it is working but when i tried to navigate from the button which is on child panel nothing happened. "i have made a function in main form which swap the content of mainpanel (displaypanel) and in childpanel i have acces the function through object of mainform"
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May 7, 2015
I can call a child method from a main method. If I have a parent called "Assessment", a child called "Quiz", and another child called "test". Can I instinate an object like Assessment a = new test(); and call a method in test.I know the method can be called if I instinate the test t = new test() but that defeats the purpose of inheritance which I'm learning in class.
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Apr 19, 2015
I understand how to write a child object. I know what can access what and the order of execution of each statement, including fields, initialization blocks, and constructors. I know what will be inherited by the child and how private fields and methods are not inherited. I also know that private fields and methods in Parent are still accessible indirectly through constructors, and non-private methods. I know how to use super() and this() with or without parameters. I know when super() will be automatically inserted by the compiler and how the Object class will always be the ultimate parent class. However, I have not been able to find an explanation of exactly (or even approximately) how all this is actually put together into an actual object in memory.
For instance, if Parent.field is private and Parent.fieldGetter() is public then Child inherits fieldGetter() and can call it directly as if it is a member of Child. In fact other classes can call Child.fieldGetter() with no clue that it is not an actual member of Child. But, if fieldGetter() is now part of Child and Parent was never actually instantiated, then how is Parent.field available for Child.fieldGetter() to read? In fact, how does Parent.field exist at all? Where is it stored? (OK, I know, "on the heap.") But I want to know what it is associated with in memory. Is it treated like part of Child? Is there really a Parent object on the heap and Child simply contains references to the parts of Parent that it inherited? What?
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Jun 22, 2014
package com.mkyong.persistence;
import java.util.Date;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
[Code] ....
Everything is working fine but in my case One customer has Many orders but when i do customer.getOrders() the child objects are not loading . I dont know why.am i missing something here im using MYSQL database
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Sep 29, 2014
Below mentioned classes, create object system accept in both way so what is it significant.
============
ABC obj = new Test();
Test obj = new Test();
==================
--file ABC class
class ABC{ public void disp() { System.out.println("disp() method of parent class"); }
public void abc() { System.out.println("abc() method of parent class"); } }
--file Test class
class Test extends ABC{ public void disp(){ System.out.println("disp() method of Child class"); }
public void xyz(){ System.out.println("xyz() method of Child class"); }
public static void main( String args[]) { //Parent class reference to child class object
ABC obj = new Test(); obj.disp(); obj.abc(); }}
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May 10, 2014
Is there a way to forward the text child of an anchor tag to its hyper reference?
For example, suppose I have an HTML file:
<a href = "ABC.jsp">SomeText</a>
Is there a way to send text 'SomeText' to ABC.jsp so it can be processed?
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Mar 23, 2014
sale s = new sale();
jDesktopPane1.add(s);
s.show();
says not a suitable method?
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