I am using mysql database and I have downloaded the library also I have managed to get the database connection and query working. I need to know if I need to create separate classes to add/remove/edit items and view items? Do I need to put my database connection script in every class that I create or should I create methods for both the connection and the queries that will be called in the additional classes or methods that I have?
Below is what I have written so far and it is working, I will change the database and query soon to reflect the task I need to do because I have followed a tutorial.
Java Code:
/**
* cdCollection.java
*/
package org.com.mm00422_prototype;
//Import for the SQL package
import java.sql.*;
//Registering the JDBC driver
//Class.forName("com.mysql.jdbc.Driver");
I think will be easy for me start with a GUI and then make things happens when the user clic on Buttons.Is there a good book about Event driven development on Java?
I have created a database driven Java app that i would like to deploy to several PCs. The App uses JReports which only worked when i installed Javac on this laptop. It worked fine within Netbeans but after building it depended on the java compiler and only worked after setting up Path variable..
Will i need to setup the Javac on every machine or is there any way of deploying it easier?
I'm reading a book titled 'Intro to Java Programming'. I understand all the Main Method stuff. I'm now reading a chapter that talks about event driven programming. I know how to do this in VBA and in C#, ut I can't figure out how this works in Java. Here's the sample code that I'm trying to run.
I'm using Net Beans IDE. When I paste that code into the IDE, I get all kinds of errors. Also, since there is no Main, I don't know how this is supposed to run. Java needs a Main Method for everything, I think. Does the Main call some kind of class?
I am new to OOP, i am not sure if this is the correct approach or not. Write a class named CreditCard that has (at least) the following member variables:
- name. A String that holds the card holder's name. - cardNumber. A field that holds the credit card number. - balance. A double that stores the current credit card balance. - spendingLimit. A double that stores the spending limit of the card holder. - Bonus: additional fields that you can think of.
In addition, the class should have the following member functions:
- Constructor. The constructor should accept the card holder's name and card number and assign these values to the object's corresponding member variables. The constructor should initialize the spending limit to $2,000 and the balance to $0. - Accessors. Appropriate accessor functions should be created to allow values to be retrieved from an object's member variables. - purchase. This function should add the amount specified as a parameter to the balance member variable each time it is called. - increaseSpendingLimit. This function should add 500 to the spendingLimit member variable each time it is called. - payBill. This function should reset the balance to 0. - Input validation: Whenever a credit card number is modified, verify that it is of reasonable length.
Demonstrate the class in a program that creates a CreditCard object and allows the user to change and view the state of the credit card with a menu driven program.
View Card Information.
- Purchase an Item: ask the user the purchase amount and increase the card balance accordingly. - Pay Bill: call payBill method to set the balance to 0. - Increase Spending Limit: ask the user how much the spending limit should be, and call the increaseSpendingLimit function the appropriate number of times.
[CODE]
import java.io.*; import java.util.Scanner; public class CreditCard { Scanner input = new Scanner(System.in); //data members private String holderName; private int cardNumber; private int accountBalance; private double spendingLimit;
I have small project to be implemented in Java, which, expected the management of a parking.
The project has a class abstract Vehicle, whence derive three classes: Car, Motorcycle, Heavy Vehicles; the cost estimated time for the 3 types of vehicles are: 2€ for Cars, 1€ for Motorcycle and 5€ for H.V.
In addition, in class Ticket will be stored the arrival time of the customer and the characteristics of his vehicle.
Finally, in the class Parking(which provides 80 places available), here it should be added the various types of vehicles.
Now, I though of using an Collection, as Set.. So that they can not, two Vheicle with same license plate.
I have a method that accepts JSONArray as parameter and returns the values of it as ArrayList Object. My question which of these ways is appropriate in populating the ArrayList object this method populates the arraylist upon creation of object (I don't know what the right term to use, but as netbeans IDE suggest, JSONArray object should be final since it was used in inner class.).
private List<String> getStringList(final JSONArray jsonArr) { return new ArrayList<String>() { { try { for (int i = 0; i < jsonArr.length(); i++) { add(jsonArr.getString(i)); } } catch (JSONException ex) { ex.printStackTrace(); } } }; }
this second method is the usual way of populating collection
private List<String> getStringList(JSONArray jsonArr) { List<String> strList = new ArrayList<String>(); try { for (int i = 0; i < jsonArr.length(); i++) { strList.add(jsonArr.getString(i)); } } catch (JSONException ex) { ex.printStackTrace(); } }
What are the advantages and disadvantages between the two? like which is faster? or which consumed larger memory?
The last line seems half cut. Does that indicate that there is memory leak in my application? I have not seen the app throwing the out of memory error.
I need to create an algorithm that finds the common element(s) in all arrays that has a signature of public Comparable[] findCommonElements(Object[] collection) that has an efficiency of at most O(knlogn), uses a query array, and accepts as input a collection of arrays. I am aware my time would be better spent learning how to use array lists and hash sets, but I am supposed to use concepts already covered, and these have not been.
I feel like this code should work, but it is returning null for the array of common elements. Which means it obviously is not working correctly. I am also likely going to need implementing the sort algorithm, but I wanted to get the part of finding the common elements set first.
public class CommonElements2<T extends Comparable<T>> { Comparable[] tempArr; Comparable[] common; Comparable[] queryArray; /* sort algorithm goes here */ public Comparable[] findCommonElements(Object[] collections)
Write a function (or functions) that given a collection of files will produce a sum of integers from each line of each file. Each file can have any number of lines from 1 to N. Each line can contain only one integer and no other alphanumeric characters. All of the numbers from all of the files should be added to the final result. The result is just one number.
17/03/2015 09:38:39 AM 17/03/2015 10:52:26 AM 10/03/2015 08:30:56 AM 02/03/2015 09:18:10 AM 02/03/2015 09:37:23 AM 02/03/2015 11:25:01 AM 02/03/2015 11:29:00 AM 02/03/2015 11:42:38 AM 02/03/2015 12:04:39 PM 02/03/2015 12:09:05 PM 02/03/2015 01:17:09 PM 02/03/2015 01:29:08 PM
I want them to sort them as per below result: (Same date one should be sort by timestamp)
17/03/2015 10:52:26 AM 17/03/2015 09:38:39 AM 10/03/2015 08:30:56 AM 02/03/2015 01:29:08 PM 02/03/2015 01:17:09 PM 02/03/2015 12:09:05 PM 02/03/2015 12:04:39 PM 02/03/2015 11:42:38 AM 02/03/2015 11:29:00 AM 02/03/2015 11:25:01 AM 02/03/2015 09:37:23 AM 02/03/2015 09:18:10 AM
I tried using Collection.sort using compareTo but result is not expected...
public class Person { private String name; private int age; public Person (String name, int age) { this.name = name; this.age = age;
[Code] .....
And I need to write a simple main method that creates lots of instances of the Person class and adds them to a generic instantiation of a Collection (ArrayList). And I need to make it so I as a programmer can define how many instances to create.
I am looking at a snippet of code in my "learning Java 4th edition" by Orielly and there is a small snipped of code which says:
Java Code: Date date = new Date(); List list = new ArrayList(); list.add( date ); ..
Date firstElement = (Date)list.get(0); // Is the cast correct? Maybe. mh_sh_highlight_all('java'); so I am typing the same thing in my compiler in a small Driver class and for some reason I have an error and Im dumbfounded...
I am having a hard time trying to wrap my head around trying to get a couple of columns in a datatable populated with values from a @OneToMany collection. The concept is simple but my brain refuses to grasp it!! I will try to make this brief...
I have several forms built with primefaces 3.5 using NetBeans 8 IDE on a JBoss EAP 6.21 server, and JPA 2.1 annotations. Data is extracted from an Oracle 11 database, which consists of several lookup tables, as well as a primary table and secondary table. Using the EntityManager createQuery method I query the database, which of course returns a resultset. The query grabs all records from the primary, as well as values from 2 specific columns of the secondary database, based on search criteria entered by the user on a primefaces search form. The returned results are then iterated through, this is where I am trying to get the values from the secondary table to populate specific fields in the datatable.Here is the applicable code from the list.xhtml form containing the datatable:
As odd as the code may look (and I will completely understand anyone cringing as to some of the coding methods I use), specifically with the ui:repeat tags nested inside the datatable tag of the list.xhtml form, I strangely do see the values from the secondary table showing up in the form showing the results in a datatable. However, when the user clicks on a specific record in the returned resultset listed in the datatable, another form is opened and populated with the values from the datatable, but the 2 fields on that form that should be populated with the 2 values I referred to before from the secondary table (i.e. policy1Num and totalPayoutAmt) do not have the values in them.
This is partly because I have those 2 fields in the editable form pointing to the managed bean of the secondary table (code from that bean not shown here), rather than the same "polNum. policy1 Num" and "totPayout.totalPayoutAmt" var I am using in the list.xhtml form. How those values are being successfully returned into the datatable of the list.xhtml form - I happened to "stumble" across the use of the "polNum" and "totPayout" vars with the "policy Payment Collection" list. I do not know how to do the same thing for those 2 fields in the editable form.how a datatable gets populated, specifically with values in a @OneToMany collection,
17/03/2015 09:38:39 AM 17/03/2015 10:52:26 AM 10/03/2015 08:30:56 AM 02/03/2015 09:18:10 AM 02/03/2015 09:37:23 AM 02/03/2015 11:25:01 AM 02/03/2015 11:29:00 AM 02/03/2015 11:42:38 AM 02/03/2015 12:04:39 PM 02/03/2015 12:09:05 PM 02/03/2015 01:17:09 PM 02/03/2015 01:29:08 PM
I want them to sort them as per below result: (Same date one should be sort by timestamp)
17/03/2015 10:52:26 AM 17/03/2015 09:38:39 AM 10/03/2015 08:30:56 AM 02/03/2015 01:29:08 PM 02/03/2015 01:17:09 PM 02/03/2015 12:09:05 PM 02/03/2015 12:04:39 PM 02/03/2015 11:42:38 AM 02/03/2015 11:29:00 AM 02/03/2015 11:25:01 AM 02/03/2015 09:37:23 AM 02/03/2015 09:18:10 AM
I tried using Collection.sort using compareTo but result is not expected.
I'm doing a project with very defined requirements. Input and output will be done to and from a file. Both the input and output files should have the same format. Each file will consist of a series of lines formatted as follows:
Year Rank Artist Title
That is, each line of the file will consist of the year, rank, artist, and title of a single song, with each of the fields separated by tabs ( ). Output files must maintain this format—you should be able to use the output file of one run of the program as the input to another run.
The first part of my project is to make a Song class, with 6 methods:
public static Song parse(String s) { //Parse a string of the form “Year Rank Artist Title” and create a Song object with the given values. } public int getYear() { //returns the year of the song } public int getRank() { //returns the rank of the song
[Code] .....
So far, I have worked out my Song class like this:
Java Code:
import java.util.Scanner; public class Song { private int year; private int rank; private String artist; private String title;
[Code] ....
I know there's definitely a problem with my parsing, as I am getting the
Exception in thread "main" java.util.NoSuchElementException
when I attempt to input a test String at my variables.
Should I try using StringTokenizer and Integer.parseInt()? I think that perhaps the reason why an error is occuring is because the String is being parsed into Strings and there are no int values to be inputted into the year and rank variables.
I am currently working on a Java project, below are my attempts at coding so far:
public class MyZoo { // zoo identifier private String zooId; // a number used in generating a unique identifier for the next animal to be added to the zoo private int nextAnimalIdNumber; // zstorage for the Animal objects private TreeMap<String, Animal> animals;
[Code] ....
I currently cannot get the printAllAnimals() method to work as it should.
When executing the method printAllAnimals(), it does not do anything, when it is supposed to use the Collection object c, so that animals stored in the zoo can easily be checked.
I have one table in DB i.e. emp. I want to perform all CRUD (insertion,selection,deletion,updation) in DB. Now i want to populate that data in jsp page. Which Collection framework?
Where should I keep a collection of instances of my custom class? In the class itself in a static variable?
class Item { int quantity; static ArrayList<Item> list = new ArrayList<Item>(); Item(int q) { quantity = q; list.add(this); } // Some methods and whatnot. }
Is it fine like this or should I implement the collection elsewhere? What say you?
I am using a IN clause in Oracle DB to pass a collection of custId to retrieve the customer details. If it was 10 or 50 custId's as a collection in IN clause it works fine. But if the collection grows bigger to 500 or 1000 then it is pretty slow to load the JSP page with the customer details.
Here is the query:-
select CustName, CustAge, CustCity, CustPin from CUSTOMER where custId IN (....)
The list of custId that is passed through Hibernate query.setParameterList()
How to optimize this query to make sure it displays the customer details faster even if the collection of elements which we pass is huge?
I am basically a Dot net developer. now im working on one Android project. my requirement is,
1. I have to call a web service, that will return XML data as String. 2. I have to read that XML string data. 3. Store those xml data into class collection(Collection is C# word, i dont know how here calling)
#1 i have done, #2 & #3 is pending. I knew reading xml is using SAX parser but, i dont know how to read from String using SAX.? Then how to store those XML data into a collection object.?
i tried with this link [URL] .... but, its confusing bcos, I am writing code Activity class but, there explaing with some Void Main class.
