Servlets :: Calling DoGet Of Child Class From Service Of Parent Class
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 .
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
For some reasons my servlet doGet method is being called twice. I am calling servlet from the index.jsp page by using servlet annotation "/Profile/*. And it passes path as localhost:1919/Profile/username to getPost method.
My profile.jsp page uses java code to show all the data (and it shows it perfectly). But then I click link to the next update_profile.jsp page. Just simple link. Then I realize that on this step for strange reasons for me doGet method from Profile servlet is called the second time. And passes path as localhost:1919/Profile/update_profile.jsp
And update_profile.jsp file is just simple file with <h1>hello</h1> output. I have looked in the internet that this might be a mapping problem or my css relative path connection problem. As you see I have commented out my css connection and problem still exists. My run output in the IDE also shows these errors:
org.apache.jasper.JasperException: An exception occurred processing JSP page /profile.jsp at line 27
Stacktrace: at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:335) at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
[Code] .....
And my tomcat run configuration settings: [URL] .... and [URL] ....
I have a quick polymorphism question. I have a parent class and a sub class that extends the parent class. I then declare an array of parent class but instantiate an index to the sub class using polymorphism. Do I have to have all the same methods in the child class that I do in the parent class? Here is an example of what I mean.
public class ParentClass { public ParentClass(....){ } public String doSomething(){ } } public class ChildClass extends ParentClass { public ChildClass(....)
[Code] ....
Is polymorphism similar to interfaces where the child class needs all the same methods?
I have an Abstract Class called GameColorEffect which contains a number of non-static Inner Classes that extend their Parent Class, GameColorEffect. I want to be able to create instances of the Inner Classes, however my IDE, eclipse, prompts me with the error:
No enclosing instance of type GameColorEffect is accessible. Must qualify the allocation with an enclosing instance of type GameColorEffect
And eclipse shows me a possible solution which is to turn the Inner Classes to static, this would allow me to create instances, but not really. This is because using methods from the static Inner Classes that change values in the Inner Classes will do this for every instance of the same Inner Class which is literally like a single instance. However, I want these Inner Classes to be individual with their values and still be able to use them outside as instances. I've found out a possible solution, which I'm not sure works like I want it to:
Java Code : GameColorEffect = new GameColorEffect.ExampleEffect(); mh_sh_highlight_all('java');
However, this is in-compact because sometimes all I need is to use just a method like:
Java Code : new GameColorEffect.ExampleEffect(intensity).applyEffect() mh_sh_highlight_all('java');
And another solution that I already knew prior was that I could make the Inner Classes proper classes not inside of the GameColorEffect class, but this is also in-compact because I will have to have so many classes for the so many effects that I have.
1. I want to use a scanner in my child class so that I may populate my parent class. It won't allow me something about scanner constructor. I posted this issue second which is my child's method Tests
2. I can't call my addTestsAnswers method from main to my child class but can call my child's display method from main.
import java.util.Scanner; public class Tests extends Assessment{ private String q; private String a; private int userInput; Scanner scan = new Scanner(); Scanner scn = new Scanner(); Scanner u = new Scanner(); public void addTestsAnswers(){
i am having a problem while calling a method..i am having a class
Java Code:
public class MySer implements Runnable { public void getMessage(String msg) { ..., }.., } mh_sh_highlight_all('java'); i use the above class in another class
In the process of creating a new class, I need to move my main method from the class SaveDate to the class DynamicTest. Below I have listed the code of both classes.The objective is to be able to run my program from the DynamicTest Class. I need understanding the process of moving my main method to a different class and creating an Object of a class and calling its method.
public class SaveData { private static final Map<String, Object> myCachedTreeMap = new TreeMap<String, Object>(); public static final List<String> getLines(final String resourceParam, final Charset charset) throws IOException{ System.out.println("Please get: "+resourceParam); if (myCachedTreeMap.containsKey(resourceParam) ) { // Use the cached file, to prevent an additional read.
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 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>()
// Add range to Vehicle. class Vehicle { int passengers; // number of passengers int fuelcap; // fuel capacity in gallons int mpg; // fuel consumption in miles per gallon
// Display the range. void range() { System.out.println("Range is " + fuelcap * mpg);
[Code] ....
I'm compiling it in Eclipse and this continues to show in the console display
Minivan can carry 7. Exception in thread "main" java.lang.NoSuchMethodError: Vehicle.range()V at AddMeth.main(AddMeth.java:34)
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) ....
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)
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'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;
I am working with a program where I am required to use a JFrame in a child class. The only way that I know how to access a JFrame is to do, example (public class Example extends JFrame), but since it is already extending the parent class, I am kind of stuck. I do not think that you can extend two separate classes, so..... I am stuck.
I created a new servlet to download a pdf-file from a unix-server and display it in an iFrame. The servlet gets called, downloads the pdf, throws away the session parameters and then... starts over again. The session parameters aren't there anymore and the servlet returns an error. The strangest thing is, in our development environment the thing works.
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...
I am new to web services and need to call a web service that has already been written. Below is the wsdl for the web service.I need to call the web service from my java program. provide the code to call the webservice?
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
