Build A Servlet That Does Simple Addition And Subtraction?
Dec 10, 2014
I am trying to build a servlet that does simple addition and subtraction then re displays the result on the same screen. I started the building the servlet I am just not sure I understand how to assign the value from a text area to a variable, so that I can complete the logic its still early stages, but its a simple app so it wont be a very long project(I hope lol). My question is how to assign the value that the user inputs to the text area to a variable that I can use?
My code and compile time errors:
C:UsersReignDesktopHTMLBank.java:89: cannot find symbol
symbol : variable Amount
location: class HTMLBank
if(Amount.equals("")||Amount.equals(null))//||Amount.equals(<0))
I need creating a code that will create random addition or subtraction from 0-500 depending on their grade level. I know how to create a random for the math and subtraction. I just dont know how to get it to change depending on their grade level. Example I need it to ask their name, grade level, addition or subtraction then five addition or subtraction questions depending on what they chose.
Started ok i guess? But when it comes to the save and get methods im totaly lost.. (See the code)
import java.util.HashMap; public class Model { HashMap<Integer,Long> m = new HashMap<Integer,Long>(); Integer value; Long result = 2 * computePower(value-1); public long computePower(int value){ if(value <= 0 )
I'm new to Java. I have a problem with this code, wherein you have to count how many times you borrow in order to do subtraction.
For example: x = 312; y = 34;
The output should be: 2 because you have borrowed 2 times in subtraction.
My problem is like this, whenever I input x=12, y=2, the output is 1, also, when x = 12, y = 1. It should be 0.
Here's my code:
import java.util.Scanner; public class BorrowOut{ public static void main (String [] args){ Scanner in = new Scanner (System.in); int x; int y; int i = 0; int j = 0;
I work as a golf staff I would like to create application which would tell me the playing time and the time when players need to reach certain playing field/hole. my ideas is to make a program which would ask the user to input their starting time and than select the hole number, where the end result would be amount of actuall time.
I have been having hard time to figure out howe to properly structure the input conversion so it is recognized as a time (Exampke: 10:15). Do I need to use the calendar method in Java or ?
When addition operation is performed on the character variables ,then it specifies actually that the ASCII values are added because the character variable stores ASCII value of the character constant ,then why after the addition the result cannot be stored inside a character variable ,why it needs to be stored in an integer variable only ,when actually the character variable stores the ASCII value then why is it an error to store the added result in an character variable.
import java.util.*; public class SumOfAllEvens { public static void main (String[] args) { Scanner s = new Scanner (System.in); //for (int i=1; i<4; i++){ int usernumber;
[code]....
I'm supposed to use a for loop that runs until it reaches the number input by the user, but I'm not sure how to tell the program to add the user's number along with all of the even numbers in between the user input and 2.
I am trying to learn how to use file input/output in addition to exception handling... The problem is my textbook wrote this chapter for a version of Java that hasn't come out yet, so everything I do "according to the textbook" doesn't work. any feedback on correcting these exception errors because I am not sure what is causing them or how to fix them.
I was able to have it display the name of the book in the Book.txt file, but when I added the second part if the file doesn't exist, that's when the errors came up and it wouldn't compile.
import java.io.*; import java.util.*; public class DisplayBook { public static void main(String[] args) { try { File book = new File("Book.txt"); FileInputStream in = new FileInputStream(book);
[Code]...
These are the compilation error messages I am receiving: (I have managed to get it down from 7 errors to just 4, but now I'm stuck)
DisplayBook.java:15: error: unreported exception IOException; must be caught or declared to be thrown while ((letter = in.read()) != -1) //if file exists, displays book title ^ DisplayBook.java:24: error: unreported exception FileNotFoundException; must be caught or declared to be thrown
how to build a GUI. I typed (not copy and paste) this code line by line to understand and get a meaning to each command. I ran into some errors while compiling and decided I would try to fix it. I ran into a problem there.....
He said that if you need something that Swing can't provide, like a bar graph, you build it. Now, being used to just writing a method that will open up a JFrame, how you would actually build graphics on your own. How in the world would that work? How would one write their own methods to make a window or to build a graph?
how to build GUI's with JFrame and I was firstly very confused as to when and what is always needed for any GUI in Java. How do I know everything I need for a GUI? Are there certain things every GUI will need by default?
Additionally below I have a code snippet of when this person used the "this" as an argument to a JButton and Im just really confused for when I can use it and when I can't.
public UIStuff(){ super("Multiple Button Events"); init(); } // end multi-button
Got a problem with generics, which I'm still pretty new at. Here's a program that compiles fine:
import java.util.ArrayList; import javax.swing.JComponent; public class Experiments { public static void main(String[] args) { ListHolder holder = new ListHolder();
[Code] ....
It's useless, but it compiles. If I change Line 14, however, to add a generic type parameter to the ListHolder class, Line 10 no longer compiles:
import java.util.ArrayList; import javax.swing.JComponent; public class Experiments { public static void main(String[] args) { ListHolder holder = new ListHolder();
[Code] ....
I get this error:
Uncompilable source code - incompatible types: java.lang.Object cannot be converted to javax.swing.JComponent at experiments.Experiments.main(Experiments.java:10)
Apparently, the introduction of the type parameter leaves the compiler thinking that aList is of type Object. I can cast it, like this:
JComponent c = ((ArrayList<JComponent>)holder.aList).iterator().next();
That makes the compiler happy, but why is it necessary? How does adding the (unused) type parameter to the ListHolder class end up making the compiler think the aList member of an instance of ListHolder is of type Object?
i have a problem, i need build a calender in BlueJ. The program need to found if I put this one year have to give me the full schedule but only the first semester.
I am trying to build an address book, and I started from what i know how to do.
public class Persona { String nome; String indirizzo; int cellulare; public Persona(String nom, String ind, int cel) { nome = nom; indirizzo = ind; cellulare = cel;
[code].....
Now I would like the program to take a string I insert on command line (for example java Cerca"Robert Baratheon") and compare it to the nome field of every Persona in the address book.
I need a summary of the steps involve in building java application.I have my source code, already compiled but I don't know the next step to make it run on a particular device. I know of emulator but I need more information.
And in the server log there is a long list of comments, the first which looks to be of significance to this issue is:
WARNING [http-apr-8080-exec-57] org.apache.catalina.deploy.NamingResourcesImpl.cle anUp Failed to retrieve JNDI naming context for container [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/transBoard]] so no cleanup was performed for that container javax.naming.NameNotFoundException: Name [comp/env] is not bound in this Context. Unable to find [comp].
There are others further down the list which might also be significant such as:
SEVERE [http-apr-8080-exec-59] org.apache.catalina.core.ContainerBase.addChildInt ernal ContainerBase.addChild: start: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/transBoard]]
The corresponding line of code for the first warning that I listed is for the DataSource object and I wrote it as follows:
