Differentiate System And User Defined Classes
Mar 16, 2014
How Can I differentiate the System classes and user classes in my program written below by another program?
/**
* Employee Class containing all non-primitive data types.
*
*/
class Employee{
private String name;
private String phone;
private Integer age;
private Float salary;
[Code] ....
Any Technique that will decide which one of the fields (Integer, Address, DOB, String, Float) are user defined type. (An outsider class should used that will identify the Java classes and the user-defined classes.)
View Replies
ADVERTISEMENT
Dec 3, 2014
I know that I am not 100% comprehending try/catch blocks, but after scouring message boards, forums, and Oracle, I still can't pick out where I am going wrong.
I have a ValidateInput class where I am trying to check that a String only has letters. If not, then throw an exception message via JOptionPane. I created my own NonLetterException class. When I call the method containing the try/catch Eclipse gives me an Unhandled Exception Type error.
in main()
ValidateInput validate = new ValidateInput();
String name = "error";
for(int x = 0; x < 1;){
name = JOptionPane.showInputDialog("Welcome. What is your name?");
boolean isItName = validate.stringInput(name); //error appears at validate.stringInput
if(isItName)
[code]....
Aren't I handling it in the try/catch? What did I miss?
Also, I have have tried the NonLetterException class as nested in ValidatedInput, but also not nested. To me nested makes more sense. I have never nested classes before, but it makes sense to me because I am not using this exception in other parts of my program.
View Replies
View Related
Aug 29, 2014
My question is How to write a program to implement concept of creating user defined packages and importing the same? How to solve it.
View Replies
View Related
Apr 7, 2015
how to add an a user defined int into my existing array. Ive heard of using ArrayList but not sure how to implement it.
View Replies
View Related
Mar 15, 2015
I'm currently trying to build a project for a mock checkout system. Basically it has to allow for users to browse through a list of items and add and remove products to the shopping cart as well as keep track of everything, dynamically updating the total price of the items in the checkout. In addition I also have to allow for the use of multiple checkouts. I have the main gui built but just trying to ascertain the best manner in which to build everything behind it.
View Replies
View Related
Apr 9, 2015
I'm trying to build a program that will output what will ultimately look like a simple mario level turned on its side. As part of my output I need the user to define what mario looks like. I do this using Scanner and save the input to String mario. When I try to use that variable in another method it gives me troubles.
import java.util.Scanner;
public class Mario2
{
public static void mario() {
//user defines mario
String mario = ">->O";
Scanner keys = new Scanner(System.in);
System.out.println("What does mario look like?");
mario = keys.next();
System.out.println("Mario now looks like: " + mario);
[code]....
View Replies
View Related
Sep 1, 2014
I am trying to remove the duplicate elements from ArrayList using .contains() if elements are primitive datatype it works but user-defined datatype does not work.
public class UserBean {
String name;
String address;
public String getName() {
return name;
[code]....
View Replies
View Related
Mar 15, 2015
The question states: Design a class named LinearEquation
for a 2 x 2 system of linear equations:
ax + by = e
cx + dy = f
Where
x =
ed − bf/ad − bc
y =
af − ec/ad − bc
The class contains:
- Private data fields a, b, c, d, e, and f.
- A constructor with the arguments for a, b, c, d, e, and f.
- Six get methods for a, b, c, d, e, and f.
- A method named isSolvable() that returns true if ad−bc is not 0.
- Methods getX() and getY() that return the solution for the equation.
Write a test program that prompts the user to enter a, b, c, d, e, and f and displays the result. If ad − bc is 0, report that "The equation has no solution."
I believe that my program is correct because I am able to compile it and get no errors, however I have no clue how to display the information for x and y or display this equation has no solution if ad-bc=0.
Java Code:
import java.util.Scanner;
public class Exer911 {
public static void main(String[] args){
// Create a scanner system to hold the numbers for each variable
Scanner input = new Scanner(System.in);
// Prompt the user to enter a number for each of the variables
[Code] ....
How to get the information to display ....
View Replies
View Related
Jan 20, 2015
so i'm following a java tutorial from the book and it has a few challenge questions. and i'm stucked on one. i think i just don't understand what is it that its asking me. heres the question, Write a statement that reads a user's input integer into the defined variable, and a second statement that prints the integer. assuming scanner is given, and i checked my heading code is ok.
Scanner scnr = new Scanner(System.in);
int userNum = 0;
System.out.println("What is the product of 8 time 2");
userNum = scnr.nextInt();
[code]....
View Replies
View Related
Jan 10, 2015
I'm using a PrimeFaces UploadedFile xhtml page to select a csv file to read and write using a managed bean (SuperCSVParser.java). The file is read and written to an entity class which then persists the data to a database. The application works fine if I specify a file path on the physical server and select a csv file on that file path. But for the production version I want the user to select ANY file name from ANY directory on their local system.
I know about the FacesContext methods and I've looked at some methods from the java.io File class. Most of these methods are about getting the path from the server, where I want to 'pass' the path String from the client machine to allow the uploaded file to go through. When I try with the below code I get:
java.io.FileNotFoundException: data.csv (The system cannot find the file specified)
I'd like to know what I'm doing as I prefer not to explicitly declare a path in the final app. I'm almost sure that's possible.
<h:form enctype="multipart/form-data">
<p:fileUpload value="#{SuperCsvParser.file}"
mode="simple"
auto="true"
[Code].....
View Replies
View Related
Mar 16, 2014
I understand that the following is an example of valid reference in java. I also understand that at class creation, first i and j are initialized to 0. j is then re-initialized to 5, as a result of which i's value is 0 and j's is 5 inside main.
class J
{
static int test() {
return j;
}
static int i = test();
[Code] ....
But why is the same not true for the following ? Why is it that i and j are not initialized to the default value of 0 in this case and gives an illegal forward reference?
class test
{
static int i = j;
static int j=5;
public static void main(String[] args) {
System.out.println(i);
System.out.println(j);
}
}
Why is it legal forward reference when using a method, and illegal when pretty much the same thing is done using a variable ?
View Replies
View Related
Apr 23, 2014
In My application I want to implement functionality to let user login from only one system at a time. I am searching for something that can Identify the system uniquely (Like IP address or Mac address ). I am using servlet and I don't know how to access Mac in servelt
View Replies
View Related
Jun 6, 2014
So I'm trying to create a simple user database that I could eventually turn into a login system. I created a simple table on MySQL with a name and address for the sake of simplicity. I tried to create simple statement inside my main method that would connect to my MySQL server and when I run my program I get a ClassNotFoundException from "org.gjt.mm.mysql.Driver"..Here is what I have in my main method thus far:
public static void main(String args[]) {
try {
Class.forName("org.gjt.mm.mysql.Driver"); //Load the driver
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/data", "root", ""); //Connect
/*
conn.createStatement().execute("CREATE TABLE people (" + "id int(64) NOT NULL AUTO_INCREMENT," + "name varchar(255) NOT NULL," + "address varchar(255) NOT NULL," + "UNIQUE (id)," + "FULLTEXT(name, address))");
[code]....
I downloaded Connector/J in the the binary .zip form and extracted it to my C: drive and put the .jar file into my java directories lib folder. I also added the directory of the .jar file into my CLASSPATH and I still get the exception.
View Replies
View Related
Apr 14, 2014
I am new a creating GUIs and am not quite sure how to correctly make one. I have done the inheritance parts, and created two extra appliances: a washer and dryer. Now Creating the GUI ....
Here are the instructions to my project.
Introduction to GUIs (+ some inheritance)
For this assignment, you are going to create a user interface that interacts with the setters and getters of some classes that you will create.
First, create an abstract class called Appliance. This abstract class should have two attributes (dealing with household appliances) and two abstract methods called turnOn() and turnOff(). These methods should return void.
Then, create two subclasses of Appliance that represent household appliances (like a Refrigerator or Stove ((don't use those!))). These subclasses should have two attributes that are specific to the various appliance. Each subclass should implement the turnOn() and turnOff() methods. These methods should print to the command line some information about the appliance as it turns on and off.
Now, the fun part! Create a GUI interface!
Your window should have two panels: one for each appliance subclass. Each panel should have 4 textboxes (with appropriate labels) to receive/display information that correspond to the 4 attributes (2 from Appliance and 2 from the subclass) for each subclass.You also need 2 buttons on each panel: A Get button and a Set button.
When the Get button is pressed, the text boxes should be filled with the information from the instantiated object of the appropriate subclass. When the Set button is pressed, the object should then contain the information contained that the user has altered.
In your main method, you should create an object of each subclass, and prefill it with information (either using the constructor or the setters), then display your GUI. You should now be able to get and set the information for your objects from the GUI.
At least one of your attributes for each subclass should be numeric
Note that you will need to handle incorrectly formatted input (You can use exception handling to do this if you want to. Wrapper classes also will work)
If there is text in the boxes when the "Get" button is pressed, it should be overwritten by what is in the object. Remember that these two panels should both be on screen at the same time.
You don't need 2 different windows, one window: 2 panels.
View Replies
View Related
Apr 20, 2015
I need to write out code for a seat booking system. So far I have the seats displayed but when I ask the user to enter their seat column and row I don't know how to mark out that specific seat they have booked with an X or such? This is what I've done so far.
import java.util.Scanner;
public class show2
{
public static final int column = 20;
public static final int row = 10;
public static void makeReservations(int[][] seatarray, Scanner input)
[Code] ....
View Replies
View Related
Mar 9, 2015
I am new to java and I am creating a system that will ask the user to create a file that will store to a text file, Once the user created the file I have a class that will let the user input the subject name that has been created, However, I keep on getting this java.util.nosuchelementexception.Here's my code:
public void display_by_name()
{
String id, name,total;
String key[]=new String[30];
String value[]=new String[30];
int i=0;
[code]....
View Replies
View Related
May 2, 2014
I have Spring/CXF project in RAD. I have the following problem message:The servlet mapping "XXX" refers to a servlet that is not defined.
<servlet>
<servlet-name>XXX</servlet-name>
<display-name>XXX</display-name>
<servlet-class>org.apache.cxf.transport.servlet.CXFServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>XXX</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
However, The servlet was defined in the web.xml file.I searched the internet and tried a few things but to no avail.
View Replies
View Related
May 23, 2015
I am trying to create a simple programme that adds two defined matrices together,
public class Question4 {
int [][] numeros1 = { {1,2,3},
{4,5,6}
};
int [][] numeros2 = {{2,5,8},
{3,7,9}
[Code] ....
View Replies
View Related
Feb 13, 2014
In my main method I am trying to create a Timer, but when I put new Timer(1000,listener) the constructor is not defined. It is when there is nothing in it. I find this super weird because in all my other programs this does not happen. I looked at the documentation and can't see what I am doing wrong, so I turn here.
ActionClass Java Code: import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.*;
public class Action extends JComponent {
[Code] .....
View Replies
View Related
May 25, 2011
I'm having an issue when I try to define a variable in a JSP scriptlet, and then in a separate scriptlet on the same page attempt to use the variable. It looks like it goes out of scope.
I also cannot reference a variable from a servlet in a JSP expression tag. So I've had to write the entire page basically in one scriptlet.
I'm using Tomcat 6.0.
View Replies
View Related
Apr 1, 2014
I have a small issue understanding the following error message that Eclipse returns when i try to run the following code:
class Film {
String tytul;
String rodzaj;
int ocena;
void odtworz() {
System.out.println("Odtwarzamy film.");
[Code] .....
The message itself reads: "Exception in thread "main" java.lang.Error: Unresolved compilation problem:
at FilmTester.main(Film.java:13)"
and the following on the line where the problem arises:
What gives? I'm positive i'm missing something obvious but i can figure it out why
View Replies
View Related
Jul 11, 2014
1.Is there any way by which i can see what is happening inside pre defined methods.
i.e. can i see there source code?
2.Somewhere i learned how to see the content of a pre defined class i.e. by using:
javap java.io.classname
but i dont know what javap means!
View Replies
View Related
Feb 15, 2014
Can a class be defined inside an Interface .
interface Inter{
class x{
public static void main(String[] args){
System.out.println("Hello World!");
}
}
}
View Replies
View Related
Feb 15, 2014
What happens to a static variable that is defined within a method of a class ?
View Replies
View Related
Aug 7, 2014
I am currently in the middle of a certification program and doing quite well but now I am a bit stuck.
I have two classes in the program, one defines a box based on drawRectangle, the other is a simple Applet to display the box. This is the Box - Class :
import java.awt.Color;
import java.awt.Graphics;
public class Box {
private int upperLeftX, upperLeftY, height, width;
private Color boxColor;
[Code] .....
View Replies
View Related
Mar 30, 2014
Why I cannot use 2 public classes like below?
public class Hello {
public static void main(String[] args){
Welcomer welcomer=new Welcomer();
welcomer.sayHello();
[Code] ....
Exception in thread "main" java.lang.Error: Unresolved compilation problem:
The public type Welcomer must be defined in its own file
at Welcomer.<init>(Hello.java:9)
at Hello.main(Hello.java:5)
View Replies
View Related
