Trap Primary Key Violation Exception?
May 30, 2014
i have a table with two columns as primary key i what to trap exception if the use in UI try to enter duplication in the table i don't what to throw ORA ERROR i what to display meaningful error massage,my database is oracle 11g
this is how i what to do it
i what to add integrity constraint to the table, and i use explicitly name it.
- i test the database to figure out what exception it returns for that constraint. With luck the name i used will be in the text of the exception.
- i add a catch to my database layer that catches SQLException, looks for the error message, and then throws a different exception, probably my own message
- In my UI layer catch that specific exception and convert it to something appropriate.
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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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May 29, 2014
How do you do validation in java for primary key lets say the table got combination of two columns as primary key,how can i validate that if use enter already existing value...
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Jan 20, 2015
I thought numeric literal were by default int or doubles, depending on if have a . and numbers after the But I wrote a quick test program as listed below. I understand the float float floatA = 5.5; failed to compile since 5.5 is a literal of type double and you are trying to assign this to a floag
What I am having problems with is byte byteA = 5; 5 is a literal of type int and this is being assigned to a byte and compiler should complain.The compiler does not allow two byte values to be added and assigned to a byte since the result of the addition is an int
class literalTesting{
public static void main(String[] arg){
byte byteA = 5; // allowed WHY I thought literal is an int and assigning int to byte
byte byteB = 10; // allowed
[code]...
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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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Jan 24, 2014
I was giving a quick skim to some tutorials on the internet where I have found the exception that is handled is also declared in the throws clause of the method wrapping the try-catch block. For a code representation consider the following:
public void methodName() throws IOException {
try {
...
} catch (IOException ex) {
.... TODO handle exception
}
}
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Sep 29, 2014
Right, so I got this program. It takes input from the user and assigns it to fields on an object. But, it's meant to check the users input. If the user enters bad input, it's supposed to throw this exception. For each of these exceptions, theres a class specifically for it.
public class PayrollDemo
{
public static void main(String[] args)
{
Payroll pr = new Payroll ("Test Name", 234);
System.out.println("Current Employee Information.
");
System.out.println("Name: " + pr.getName());
System.out.println("ID: " + pr.getID());
System.out.println("Hourly Pay Rate: " + pr.getHourlyPayRate());
[Code] ....
And this is the exception class.
public class InvalidNameException extends Exception
{
/**
No-arg constructor
*/
public InvalidNameException()
{
super("Invalid name");
}
}
PayrollDemo.java:43: error: cannot find symbol
InvalidNameException.InvalidNameException();
^
symbol: method InvalidNameException()
location: class InvalidNameException
1 error
It's just meant to tell the user that they entered an invalid value, which would mean if they entered an empty string instead of a name.
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Jan 4, 2014
I have a program which runs perfectly fine in Eclipse. however, the same program after exporting to jar in desktop and then executing in cmd gives exception.
why is this difference.
in eclipse. it is built up 1.6 JDK and run using 1.6 JRE.
in CMD, it runs by 1.7 JRE.
can this JRE version make a difference. Technically should not i believe.
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Mar 15, 2014
value1 = text1.getText();
value2 = text2.getText();
Connect c = new Connect(value1,value2);
if(c.check()== true)
{
Menu start = new Menu(c.getID());
dispose();
[code].....
I get an error "unreported exception java.SQLException; must be caught or declared to be thrown" how can i solve this I have taken a few basic classes but never got to exceptions.
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Oct 16, 2014
I want to encrypt and decrypt a txt file by using PGP.I completed my PGP Encryption.I'm getting an error in PGP Decryption. The error msg as follows
Quote:
Exception in thread "main" java.lang.IllegalArgumentException: Invalid PGP message
at com.newpackage.bouncy.PGPUtils.getDataList(PGPUtil s.java:502)
at com.newpackage.bouncy.PGPUtils.decryptFile(PGPUtil s.java:198)
at com.newpackage.bouncy.PGPFileProcessor.decrypt(PGP FileProcessor.java:56)
at com.newpackage.bouncy.Tester.testDecrypt(Tester.ja va:46)
at com.newpackage.bouncy.Tester.main(Tester.java:61)
I am getting this error in the following line of my code.
PGPObjectFactory factory=new PGPObjectFactory(PGPUtil.getDecoderStream(is));
=>> Object obj=factory.nextObject();//here i am getting obj as null
if (obj == null) {
//System.out.println("Invalid PGP Message");
//System.exit(0);
[Code] .....
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Aug 10, 2014
So I've been working on this program to make tournament matches for beach volley.
First little info: (I'm Belgian so some words are Dutch)
-Class Speler: has arraylist with information with which player already has been played (codesLijst)
-Class Inschrijvingen: makes players sign up with their level and name
-Class Wedstrijd: makes matches, checks with Inschrijvingen if the players already have played together. If so, gives message that they need to change partner. If not, makes them a team.
Now if I run the program with fresh players, none of them have had a partner, it works fine. If I make just one new team and the other already exists, it also works fine. It's when I make the two teams with existing records (to see whether they already played together), that the error comes.I know there's a lot of code duplicate, will clear out eventually, this is just a raw version.
CLASS SPELER
import java.util.ArrayList;
public class Speler {
private Wedstrijden wedstrijd;
private Inschrijvingen inschrijving;
private String naam, ploeg;
private int setPunten, winPunten;
private long time;
private String code;
private ArrayList<String> lijstCodes = new ArrayList<String>();
[code]....
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Feb 3, 2015
class Arg
{
public void rt()throws Exception
{
System.out.println("hi");
throw new RuntimeException();
}
public static void main(String args[])
[code]...
the way to handle the exception that has been in the catch block{b.rt()} .
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Jan 18, 2014
I have the below code :
public class Beyond {
static Float i;
public static void main(String[] args) {
float y = 7 * i;
}
}
It gives : Exception in thread "main" java.lang.NullPointerException : Line 5...Why is it giving NPE? Isnt the variable defaulted with 0.0f? Also, I am not performing any dot operation, it's just a multiplication operation.
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Nov 24, 2014
Why I have this out of bounds exception? I highlighted the code that the error is in
public String encrypt() {
//TODO: Complete this method
int groupMoves = 0;
int testing = 0;
String encrypted = "";
//a b c d e f g h i j k l
//1 2 0 1 2 0 1 2 0 1 2 0
[Code] ....
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Feb 10, 2015
i rewrote this code from head first java book . but every time i try to compile it it gives me this exception
java.lang.ExceptionInInitializerError
Caused by: java.lang.RuntimeException: Uncompilable source code - simpleFrame is not abstract and does not override abstract method actionPerformed(java.awt.event.ActionEvent) in java.awt.event.ActionListener
at simpleFrame.<clinit>(simpleFrame.java:6)
how can i instantiate simpleFrame class if i shoild make it abstract?
public class simpleFrame implements ActionListener{
JFrame f;
public static void main(String[] args){
simpleFrame s = new simpleFrame();
[code]....
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Apr 4, 2013
I was trying to contact many servers. The lookup was successful, but the procedure call caused the error:
java.rmi.ConnectException: Connection refused to host: 127.0.1.1; nested exception is:
* java.net.ConnectException: Connexion refusée*
What would cause this error during the call.
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Mar 3, 2014
I'm trying to insert numbers in a array of Integer neatly. When i try to insert the following numbers i have this exception.
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at time.Historico.insere_ordenado(Historico.java:35)
Line 35 in my code is:
"while (num >= arry[i] && arry[i] != null && i < arry.length - 1)"
Numbers:
71516357248031
I have this exception when i try to instert 80.
public Integer[] insert_neatly(Integer[] arry, Integer num)
{
Integer i, acum, aux, temp;
i = acum = 0;
if (arry[i] == null)
[Code] ....
What is wrong with this code?
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Jan 29, 2014
I have studied that Generics are used to shift the Class Cast Exception into Compile time errors , So that we get errors at compile time error and we do correct them before executing ,but Here is a program in which i am getting Class Cast Exception
class Animal
{
}
class Dog extends Animal
{
}
class Cat extends Animal
[code]..
Getting Exception at line no 29 which i know why it occurs but just wanna ask that isn't it should be caught at compile time According to Generics ?
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Aug 17, 2014
Is there any connection between packages and exception handling in java. Means is it necessary to create a package before trying exception handling examples?
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Jun 10, 2014
how inheritence and exception work together ?? what are the rules ??
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Apr 22, 2014
Is there a special mechanism through which exception can be handled in a constructor?
Suppose while creation of an object there occurred an exception while creating an object, and the object is half constructed. How do we make sure we handle this kind of exceptions in a constructor?
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Dec 15, 2014
I am trying send email .So I have downloaded javaEE and javamail jar files and added buildpath.And wrote this code below .But I am getting this exception.
Exception in thread "main" java.lang.RuntimeException: javax.mail.AuthenticationFailedException: 534-5.7.14 <https://accounts.google.com/ContinueSignIn?sarp=1&scc=1&plt=AKgnsbskV
534-5.7.14 ggcPi6MBZ4h8CCyCk2TG9EhiTGyE5MVBv7B3k7DsCldqjCuFvMTQG6aAbatrAWggH29muG
534-5.7.14 dzVh1kUYgMgNHAN558QRCnTjrNtUGv34Ul4pzUaansBuBfB0Kpz6_q7JTbrUuAmlZplouA
534-5.7.14 AHDXpFtuCkd-W17tHrZS5mqgVVxAcuKc-7TkhCDGShnfRBWU2R8v-gfvIQShszqsZmCl0i
[Code] .....
What am i missing here.
public static void main(String[] args) {
final String username = "mymail@gmail.com";
final String password = "mypass";
Properties props = new Properties();
props.put("mail.smtp.auth", "true");
[Code] .....
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Nov 25, 2014
For one of my last labs for the semester, my professor is having the class go back to our very first program and apply some of the exception handling that we just recently learned about. Here's my improved code so far:
Java Code: import java.util.*;
import java.lang.*;
public class Lab2Part1 {
public static void main (String [] args) {
Scanner input = new Scanner (System.in);
[code]....
My code compiles fine, but even if I enter an integer or a double, it saves the number as a string, and prints that out as the name. Is there any way to get around this? Or do I need to use something besides a try-catch?
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Sep 28, 2014
Why I have to place two parameters in the Verify constructor. If the numbers are being typed in by the user and passed through the validate method, what is the point of having them in Verify() ?
First, create three exception classes named NumberHighException, NumberLowException, and NumberNegativeException. Both NumberHighException and NumberLowException should be directly subclassed from the Exception class, but NumberNegativeException should be subclassed from NumberLowException. You can use the BadDataException class that was defined in this module as the model for your exception classes.
Next create a class called Verify that will be used to validate that a number is within a specified range. It should have one constructor that has two int parameters. The first parameter is the minimum number in the range, and the second parameter is the maximum number in the range.
In addition to the constructor, the Verify class should have one method that is named validate. The validate method should have a single parameter of data type int. The parameter contains the number that is being validated. If the value of the parameter is less than zero, the method should throw a NumberNegativeException. If the value is less than the minimum value of the range, it should throw a NumberLowException. If the value is greater than the maximum value of the range, it should throw a NumberHighException. If the value is within the specified range, no exception should be thrown.
Once all of these classes are created, create the driver class called Program5. The driver class should instantiate a Verify object with a range of 10 to 100. It should then do the following:
-Prompt the user to input a number within the specified range.
-Use a Scanner to read the user input as an int. You can ensure that an int was entered because the nextInt method throws an --InputMismatchException if any non-digits are entered.
-Call the validate method to validate that the number is within the range.
-Print an appropriate error message if the value is not within the range, or print the value if it is within the range.
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Oct 10, 2014
need to navigate/render a jsp when a custom exception is thrown from a code block in my app.for that in web.xml I have configured the error handling
<error-page>
<exception-type>com.exampl.RecordNotFoundException</exception-type>
<location>/WEB-INF/errorpages/recordnotfound.jsp</location>
</error-page>
Code block
@RequestMapping(value = "/record", method = RequestMethod.GET)
public ModelAndView getPages() throws RecordNotFoundException{
throw new RecordNotFoundException("E888", "This is custom message X");
}
My questions are:
Is this the correct way to invoke a jsp when my code throws an exception?Do I need a try catch block to handle the thrown RecordNot Found Exception, if yes how would I navigate to the jsp from the catch block?
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Aug 14, 2014
It is supposed to create an array of random strings and sort them according to their HTML numbers. It creates the array correctly and even compiles correctly, but has a null pointer exception when it comes to the sorting. (I have cut out other parts of the program that were irrelevant).
the lines that produces the null Pointer Exception is line 24. if(array[i].charAt(0)>array[maxIndex].charAt(0))...and 53.stringSelectionSort(stringArray);
import java.util.Arrays;
import java.util.Random;
/**tests the array.sort() subroutine vs. a
'selection sort' that I will write. a random list
of integers is used first and times are recorded to
determine which one is more efficient. A random list
of strings is also tested.**/
[code]....
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