Swing/AWT/SWT :: Relationship Between Super And Child?
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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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 12, 2014
I am trying to make a ChessBoard class composed of an array of JLabels inside a JPanel with a grid layout. I am also trying to override the getPreferredSize method so that the board will change size when I resize the main window (in another class in which I will instancize this class as part of a larger GUI). I got this kind of layout working before, but now I am trying to get it to work with multiple classes. However, after copying in the part of the previous code corresponding to the panel's layout, I am encountering some errors that I don't know how to solve. Specifically, when I try to override the getPreferredSize method, the compiler tells me "method does not override or implement a method from a super type, " and that it can't find the method "getPreferredSize"
Here's my code:
public class ChessBoard extends JPanel//the panel that this class extends is the boardHousing
{
//mental chess board piece array
Piece mentalBoard[][] = new Piece[8][8];
//actual GUI chessboard JLabel Array
static JLabel chessBoard[][] = new JLabel[8][8];
[Code] ....
I would just think that I was overriding the method incorrectly, but the weird thing is that I got that specific section of code to work before -- the only thing different now is that there are multiple classes, so my ChessBoard class itself is extending JPanel.
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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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Mar 23, 2014
sale s = new sale();
jDesktopPane1.add(s);
s.show();
says not a suitable method?
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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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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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Apr 21, 2014
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
PrintWriter pw = response.getWriter();
String connectionURL = "jdbc:mysql://localhost:3306/userdb";// userdb is the database
Connection connection;
[Code] .....
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Aug 9, 2014
I'm trying to understand the relationship between JAAS and JDBC..In WebSphere, when setting up a Dynamic cluster I have to first define the JAAS..Then, the datasource..The JAAS has one account/password and the datasource another..I'm not getting the relationship between needing both JAAS and JDBC docs.oracle.com/cd/E19225-01/820-5594/ahteo/index.html
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Mar 28, 2014
I am having difficulty with a sorting routine. I believe that the concept is valid (although not necessarily the most efficient), but I keep running into a problem. I am trying to use the compareTo function to identify the relationship between two values in an array, but it seems to have an issue with it being a comparison of two float values.
Java Code:
for (int x = 0; x < 430; x++) {
for (int y = 0; y < 430; y++) {
if (dataArray[y].compareTo(dataArray[y + 1]) > 0); {
tempOpen = dataArray[y];
[Code] ....
It gives the compile error as follows:
File: C:UsersBradDownloadsAssignment 3Calculations.java [line: 157]
Error: Cannot invoke compareTo(float[]) on the array type float[]
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May 8, 2012
I am implementing JPA hibernate simple application using one to many relationship.
Relation ship is Comapny (1)----------- Department(*)
Company.java is as follow :
package com.web.pojo;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
[Code] .....
What I am doing is , I am adding new department to existing company. After execution above code
Table created are :
1. Company table with id and name
2. Department table with deptId , deptName , compId.
so at the time adding department , it does not threw any exception but updates records in department as
1(Id),Development(DeptName),null(compId) .
I am not getting why it is not updating compId column.
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Jun 17, 2014
Set<? super TreeMap> s = new HashSet<SortedMap>();
SortedMap<String,String> sm = new TreeMap<String,String>();
TreeMap<String,String> tm = new TreeMap<String,String>();
s.add(sm); //This fails
s.add(tm);
Why does adding sorted map to a Set that allows ? super TreeMap and instantiated as such fail?
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Feb 14, 2014
Suppose I have
class A {
public void speak() {
System.out.println("I am class A");
}
}
class B extends A{
public void speak() {
System.out.println("I am class B");
}
}
class C extends B{
public void speak() {
System.out.println("I am class C");
}
}
Why this doesn't work while A is a super type of B ?
public static void insertElements(List<? super B> list){
list.add(new A()); //not OK, why?
}
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Feb 12, 2014
what does super(); do in the following method, I understand its uses to access variables belonging to the superclass but i am unsure of what that one line does. Here is a sample constructor..
public CreditCard()
{
// fill in the default constructor and use the super call
super();
id = "000000";
year = 0;
}
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Aug 9, 2014
I created a superclass Ships and under that a class CivilShips. Under that HumanBulkFreighter.
I declared variables in Ships and CivilShips and wanted to have them set in HBF to a specific value. When I know try to compile them I get the following:
HumanBulkFreighter.java:2: error: <identifier> expected
cargo=1500;
^
HumanBulkFreighter.java:3: error: <identifier> expected
size=200;
[Code] ....
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Jul 9, 2014
The super keyword when used explicitly in a subclass constructor must be the first statement but what about if i have a this(parameters) statements ? As the this one must also be the first statement... Does this means that i can have only one or the other ? What about when the super constructor is not explicit (aka implicit ) , can i use the this( parameters) in the same constructor ?
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Sep 18, 2014
Its written that every constructor calls its super class constructor. And we know, constructors are called to create an object. Does it mean that if I am creating an object of a class, I am actually creating objects of all its super class???
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Dec 2, 2014
how to get access from variables in a super class or a subclass. Here is what I got:
1) I have a super class that is in Jar file, I created a link in Eclipse, I know that the link is created correctly, I am going to concentrate just in one variable, so I don’t have to put all the code here firstName; in the super class(the one that is define in the path)
public class CommissionEmployee {
// Field descriptor #6 Ljava/lang/String;
private java.lang.String firstName;
in my class i have 6 argument constructor
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Nov 7, 2014
I am creating a set of 3 subclasses, 1 superclass, and an application. In my instructions it says to make set methods in my super and subclass by using dialog boxes. In the application you have 3 different arrays where you create objects and are supposed to call the methods from the subclasses to be used in the application. I don't know how to make the dialog boxes from my subclasses to show up in my application.
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Jan 3, 2015
//constructor
class Base
{
Base(int a) {
System.out.println("in base"+a);;
}
}
class Cons extends Base
[Code] .....
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Aug 13, 2014
I'm writing a simple program in which I have a super class Person, inherited by the subclasses Customer and Employee (they inherit the variables ID, name and surname).
Java Code:
public class Person {
int id;
String name;
String surname;
public Person () {
[Code] .....
However the problem is here: when I try to get the variables ID, name and surname through my main class, they fail to return (0,null,null). Why is this? I have get-Methods in my subclasses which should return the super variables, but they are not.
Java Code:
public String getUser() {
return username;
}
public String getName() {
return super.name;
} mh_sh_highlight_all('java');
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Dec 1, 2014
While reading the design patter book, i got one doubt ,There is a List an interface having sub classes ArrayList, LinkedList etc.,
Q1) My question is Why they declared the List as interface rather than Abstract class?
Q2) i read some site -
List l = new ArrayList(); Why it is GOOD line?
ArrayList l = new ArrayList() ; Why it is BAD line?
Answer required with detailed information for Q1 and Q2.
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Apr 15, 2014
For example I create an object like this:
BankAccount b = new SavingsAccount();
Now lets say that I want to access a method 'addInterest()' that is in the 'SavingsAccount' class I would have to do: '((SavingsAccount)s).addInterest();'
The question I have is why do I have to cast 'b' to SavingsAccount? Isn't the actual object reference of 'b' already an instance of 'SavingsAccount' class? How does the 'BankAccount' affect the object itself? I'm really confused as to what class is truly getting instantiated and how BankAccount and SavingsAccount are both functioning to make the object 'b'.
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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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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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