JSF :: SQL Database - CRUD With Foreign Keys
Aug 12, 2014
I am trying to work with a SQL database and some JSF pages that were created with/for CRUD. The data comes up just fine but all my foreign keys show the primary key for the key not the data. So instead of having the actual Zone I get the number (my primary key) that matches the Zone.
example:
4717A Cool ReceptionTitle: Gatherer of Cool Companycom.vancowboy.lotor_db.LotroZones[ id=11 ]
The last item should read "All" not "com.vancowboy.lotor_db.LotroZones[ id=11 ]"
This was straight from a tutorial so I can learn this but the FK has got me baffled...
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Oct 22, 2010
I am new with java, eclipse, jpa(eclipselink), postgresql, and trying to make a web application. I have two tables:
bids: id, quantity, price
trades: bidid, askid, quantity, price
bidid and askid columns are foreign keys from bids table (id), and they are the primary key for the trades table.
I created the Entities from the Tables (Bid and Trade class) with eclipse and it generated a TradePK class for the primary key.
Trade.java:
@Entity
@Table(name="trades")
public class Trade implements Serializable {
@EmbeddedId
private TradePK id;
[Code] ....
I understand that this is necessary because the primary key is from two column, but as soon I want to persist a Trade back to the database Eclipselink call the column names twice:
INSERT INTO trades (price, quantity, datetime, BIDID, ASKID, bidid, askid) VALUES (?, ?, ?, ?, ?, ?, ?)
So postgres give me back an exception: ERROR: column "bidid" specified more than once
And I don't know why. According to the JPA docs I didn't found any mistake:
Introduction to EclipseLink JPA (ELUG) - Eclipsepedia
Or I just can't see it... or is there a better doc which explains it better?
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Jun 22, 2014
I would like to create a java gui (with CRUD elements) that connect to MySQL server DB and display a table records (also insert, edit, delete data to table), and I want to know how create such a gui.
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Mar 28, 2014
I'm using Netbeans IDE and Glassfish application server. I have a JSF CRUD application running with a MySQL database and everything was fine until I was asked to be able to sort a column whose MySQL datatype was Varchar.
Here is my Model for Vehicles:
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package entities;
import java.io.Serializable;
import java.sql.Date;
import java.text.DateFormat;
import java.util.Calendar;
import java.util.Locale;
[Code] ....
So I changed the datatype to Integer and updated my source code to change the column from String to Integer. When the list displays every thing seems good and the rows are sorted according to the column whose datatype I changed to Integer.
However when I then tried to edit nothing works and I get HTTP Status 505 from Glassfish with the error message
javax.servlet.ServletException: HV000030: No validator could be found for type: java.lang.Integer
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Apr 8, 2015
My system displayed fine with thailand wordings when show in screen, but problem when come to generate excel file, it shows "???" in excel file for thailand wordings. How can i solve this ??
right_enquiry_policy_csv.jsp
From this jsp it will retrieved all details from database and store in arraylist
try{
ArrayList alAll = new ArrayList();
ArrayList alHeader = new ArrayList();
[Code] ....
Here is my excel output. It shows "???" for client with thailand name.
System display for clients details
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Jan 22, 2015
Its required to create a service to embed widgets on any foreign website(server), using servlets where i'll pass encrypted widgetId and in turn i will get html for displaying it on screen. Also a refresh button with the embedded widget is to be provided so as to fetch updated computed data. The point is that user should copy some html/script code and place it on his website.
I am thinking of following approach.An empty span with id, followed by a js script to make ajax call to the server to get widget HTML.
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May 21, 2014
The problem is i want to replace some string text with foreign characters, but JTextArea returns plainText.
For Example:
str = new String();
str.replace('e', 'é');
textArea.setText(str);
but textArea returns plainText.
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Apr 5, 2014
I am asked in my assignment to make a program that accepts a text file as an example a novel and i have to sort each word as a PERSON or ORGANIZATION or LOCATION or O as in Other , example :
Microsoft/ORGANIZATION ,/O Nelly/PERSON !/O '/O
Now we notice that microsoft is and organitzation and "," is Other and Nelly is a person's name and so on ..
Now I am asked to return the numbers of tags in the text which is 4 in our case because we have (ORGANIZATION,PERSON,LOCATION,OTHER)
My question here is my logic true ? And since i made a map of String,String ; Is there any way that i can get the size of the values in our case the values are the organization etc.. ?
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
[code].....
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Feb 9, 2014
I have one doubt.In HashMap if keys contains 1,2,3,4 and values are a,b,c,d we can get values using get(key) method like 1 will A,2 will return B and so on. Can we get the keys from values like A will get 1 and also if in key if there is a String like 1,2,3,Z and value is A,B,C,7 Z should get me 7. Here I am not using any generics.
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Jul 14, 2014
I am writing a code that tries to figure out the users password by going through every possible key (brute force). Although I think its going to work, it looks EXTREMELY inefficient to me, since its just a huge switch statement for each character -- 94 total, including the shift values. Is there a built in method in the JAVA API that goes through every key or something?
Here is my code for that segment:
public char[] HackingPassword(){
char[] passChars = this.password.toCharArray();//convert the password to char[]
char[] hacking = new char[passChars.length];//make the hacking variable same size as users password
int nextCharValue = 0;//this is used to cycle through the keyboard
//check each letter of hacking to match with password
for(int i = 0; i < passChars.length; i++){
[Code] .....
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Jul 4, 2014
I want to write a method to print the all the names of a phone book. phoneBook is a HashMap<String, String> , that has names as keys and phone numbers as values.
Reading the documentation for both HashMap and Set, I have more or less an idea of how it could be done but I cant put it on code..
public String getName()
{
String[] keys = phoneBook.keySet().toArray();
return keys[0];
}
This is wrong. It doesnt compile saying incompatible types. I was thinking first to manage to succeed to get a key from my phone book and then I change it to print all the keys.
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Dec 21, 2014
I have the following hashMap declared:
private HashMap<String, Car> cars = new HashMap<String, Car>();
How can i get an array of String filled with hashMap keys?
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Apr 22, 2014
I'm learning Java using BlueJ, I have made a class that has a HashMap of (String, String) that contains an the make of a car and the model.
I want a method to return a collection of all the keys that satisfy a condition, like if someone wants to find what make a certain model is. I know it requires a loop, just not too sure how to write the loop to satisfy the condition.
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Apr 9, 2014
I Want to identify up, down, left and right keys with the keylistener() WHATE NAME DO I IDENTIFY IT WITH
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Dec 13, 2014
Here is my HashMap and a method for listing all the keys in it
HashMap<String, String> exampleOne = new HashMap<String, String>();
public void allKeys() {
int i;
i =0;
for (String name: exampleOne.keySet())
[Code]....
Now I want to return all values that associated with one key. How do I do this? Or is it possible to other way round? I mean return All keys associated with a value?
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Aug 27, 2014
I am developing a java code using netbeans for encryption decryption by RSA algorithm. Swings and file handling play a major role in these code. My encryption code is working nicely but the code for decryption is not since keys file is not being read. That is why variable mod and pri are getting null values and the following error stack is coming. I know where the problem is somewhere in void readkeys() function but cannot solve it.
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at java.math.BigInteger.modPow(BigInteger.java:1579)
at rsakeydecryption1.RsaKeyDecryption.decryption(RsaKeyDecryption1.java:167)
at rsakeydecryption1.RsaKeyDecryption.read_output(RsaKeyDecryption1.java:294)
at rsakeydecryption1.RsaKeyDecryption.actionPerformed(RsaKeyDecryption1.java:330)
[Code] .....
My code for decryption is
package rsakeydecryption1;
import java.math.BigInteger;
import java.util.Random;
import java.io.*;
import javax.swing.*;
[Code] ....
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Mar 15, 2014
Suppose that a certain BST has keys that are integers between 1 and 10, and we search for 5. Which sequence below cannot be the sequence of keys examined?
(a) 10,9,8,7,6,5
(b) 4,10, 8, 6, 5
(c)1,10,2,9,3,8,4,7,6,5
(d) 2,7,3,8,4,5
(e)1,2,10,4,8,5
I've noticed many differences, such as there is only one with an odd number of keys, and one has all integers from 1-10 inside of it, but I can't find any real reason that you wouldn't be able to search it?
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Aug 3, 2014
I've started creating a simple game in Java, so now I'm stuck. I wanted to make moving character by fast alternating arrow keys, but I don't know how. I can make a boolean variable, which disables moving by pressing the same key again, but the player can just hold the key and character is still moving. I thought about changing position of character when the key is pressed, instead of increasing speed, but then the movement wouldn't be smooth. I think this may sound incomprehensible, so I will add a link to game like an example of what I mean.
Play Mini Sports Challenge game online - Y8.COM
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Nov 21, 2014
I need to get a clone of a fairly deep object tree. All objects are entities and I need to set the primary keys to null. The root object:
public class Grundentscheidung implements Cloneable {
@OneToMany(cascade = CascadeType.ALL)
@JoinColumns({
@JoinColumn(name = "gesamtentscheidung_dstNr"),
@JoinColumn(name = "gesamtentscheidung_id")
[Code] .....
When I call
Grundentscheidung grundentscheidungClone = grundentscheidung.clone();
grundentscheidungClone contains the whole object tree with all dependencies, but the Tatbestand objects have their primary keys. When I use the debugger I see that Tatbestand.clone() is never called.
Is my code faulty? I would like to avoid to write a large method which sets all primary keys on the object tree to null.
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Mar 28, 2014
I've visited this great site been following this java tutorial on making the snake game, and as I followed along at added the second player. Right up to the point I got into the resetting if I hit borders or myself or the other player, the snakes stopped moving when i tried hitting keys...problem started up to the point where I added snake2 in the GenerateDefaultSnake method
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.LinkedList;
import java.util.Random;
[code]....
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Feb 16, 2015
My objective here is to process a HashMap's key's in order. I found SortedSet as a way to do it.
The HashMap is like this:
nobelPrizeWinners = new HashMap<String, PrizeWinner[]>();
// 2009:
nobelPrizeWinners.put(new String ("2009 Physics"), new PrizeWinner[] {new PrizeWinner("Charles K.", "Kao"), new PrizeWinner("Willard S.", "Boyle"), new PrizeWinner("George S.", "Smith")});
[Code] ....
This is the method I am trying to write
public void displayAllYearsAndWinners_2()
{
// Creation of the SortedSet
SortedSet sortedSet = new TreeSet();
[Code] ....
However, the compiler gives me a warning of NobelPrizeWinners.java uses unchecked or unsafe operations. Recompile with -Xlint:unchecked for details.
As I said, my objective here is to process them in order. If this compiler warning cannot be resolved, I am open to other methods of accomplishing my objective.
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Jan 7, 2014
I'm working on a Java 2D game which requires a max of six keys be held down at the same time.
The game is for two players on the same keyboard, playing simultaneously.
However, all three computers I ran the program on only allow a max of three keys held at a time. They all have trouble with reacting to more than three keys being held.
It seems that pressing a new key after three are already held, either cancels some other key-holding or is ignored.
I've been told that this is a hardware issue. Most keyboards can't handle more than three keys held at a time. But a lot of games do require this, and they do not require special gaming-keyboards to run on my computer without problems.
So there has to be a solution that will make the game playable on any standard keyboard.
(I use Key Bindings).
The game's controls:
Player 1
- Rotate sprite and set angle of movement: LEFT arrow
- Rotate sprite and set angle of movement: RIGHT arrow
- Move forward: UP arrow
- Shoot missile: ENTER key
Player 2
- Rotate sprite and set angle of movement: 'A' key
- Rotate sprite and set angle of movement: 'D' key
- Move forward: 'W' key
- Shoot missile: 'T' key
Relevant code:
The Key Bindings part:
Java Code:
// An action for every key-press.
// Each action sets a flag indicating the key is pressed.
leftAction = new AbstractAction(){
public void actionPerformed(ActionEvent e){
keysPressed1[0] = true;
[Code] .....
This is mostly how reacting to key-presses and key-releases works in my program. When a key is pressed or released, a flag is set. The Board class reades the flags every game-loop cycle and reacts accordingly.
As I said, the program doesn't react correctly to more than 3 keys held at a time, probably because of the keyboard. Is there a way to code a solution?
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Mar 7, 2014
I remember, it's possible to collect multiple parameters from each line in a .txt file (with commas used as delimiters to separate each parameter on each line). My EmployeeData.txt file looks like this:
EDR2014,Bob,Marley,02/12/2011,1000.00
ARR1234,John,Fuzzy,03/23/2013,12.00
XXX0666,Matt,Pagel,08/10/2011,23.00
DIE4273,John,McLane,07/22/1995,45.00
FUK0330,Kevin,Young,12/02/2003,7.00
NFN7734,Sam,Peterson,08/01/1999,8.00
the parameters of each line are: employeeNum, firstName, lastName, hireDate, payRate
To match the specifications in the following EmployeeInfo.java class:
Java Code:
package employeepunch;
//import org.joda.time.DateTime;
import java.io.*;
public class EmployeeInfo {
[code]...
The validation of making sure the employee uses the correct format while entering his employee number is just the first part. I also need to add validation code to make sure his employee number matches one of the ones in the EmployeeData.txt file (shown earlier above).
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Apr 23, 2014
i'm new withh java netbeans, and i want to make program where variable from database. how to get value from database to use in variable/
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Jan 4, 2015
I am trying out jsp and servlets now for the first time. I have to insert two data, car code and car name into a mysql table. I got those details using jsp but if I use form, it redirects to another page for insertion. I want the data to be inserted and still remain in same jsp page. I am thinking of using onClick from javascript but as I googled this many places have said it is a bad idea to use jsp inside javascript. If so how can we insert data to mysql table without redirecting to another page?
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Apr 8, 2014
This is a general question about best practices for handling persisted data in JSF. My JSF page is going to have several fields that map to a managed bean. Upon a button click the fields of this bean are going to be persisted in a database. Is it better to use another bean with application scope to handle the JDBC code, or should I have a method in the bean itself to handle that? Similarly I'll need a method to retrieve the information upon a user request.
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