Creating Applet With Dropdown Lists - Method Not Abstract
Oct 21, 2011
i am trying to create an applet with drop-down lists. When I compile the program the following error message appears '. . .is not abstract and doesn't override abstract method action Performed. . . Here is my code . . .
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class DavidApplet extends Applet implements ActionListener //class header {
Label fName=new Label("First Name");
I am familiar with Java but new to JSP. I have a Java Servlet app where user actions are recorded in a SQL Server database amd I now need to quickly put together a JSP front end application to view user actions. I want two drop down boxes to filter the results that will be displayed in a list box. What I need is the first drop down list box to show unique user names that have logged in. I can interrogate the database with the following SQL;
"SELECT DISTINCT(USER_ID) FROM AUDIT_MESSAGE"
Then when a user is selected from the first drop down list box (perhaps some sort of on change event) a second drop down list box shows the logins times of the selected user. Again I can interrogate the database with the following SQL;
SELECT SESSION_ID, EventTIME FROM dbo.AUDIT_MESSAGE WHERE OPERATION = 'loginResponse' AND RESULTS = 'OK' AND USER_ID = 'firstdropdownlistselection'
Then finally when a login time is selected in the second drop down list box all events for the selected user while logged in with that login time are displayed in the list box.
I am trying to implement product method below which returns the set representing the Cartesian product of the current set and a given set (the Cartesian product contains all ordered pairs (a, b) where a belongs to the current set, and b belongs to the given set). The product should be a ListSet <Tuple<E>> object where each ordered pair is a Tuple element. (I have a Tuple class which implements an ordered tuple)
What am I trying to do in the product method : Make 2 for loop and inside the for loop make an array of <E> then set the 2 elements of the tuple then again set tuple and add it to arrayList. how to set 2 elements of the tuple and set tuple ??
public class ListSet<E> implements Iterable<E>{ SinglyLinkedList<E> sl; public ListSet(){ sl = new SinglyLinkedList<E>();
The assignment is to: Use arrays to create an applet that lists five of your favorite songs.
The applet should scroll the list of song titles, one at a timeeach song title should start at the top of the applet and scroll to the middle then, scroll off the right hand sideeach new song title should scroll in a different colourthe applet should loop, that is, when it gets to the end of the list, start over again at the beginning of the list
I already have it looping the text with different colors. It's just they all loop at the same time. How to loop them separately. How to switch the program to where the strings will change with content and color on each loop that would work too.
Here is the code I got so far:
import java.awt.*; import java.applet.Applet; public class FavouriteSongs extends Applet implements Runnable { String[] Songs = {"Travelling Man-Chameleon Circuit", "Sing-Ed Sheeran", "It's Time-Imagine Dragons", "I See Fire-Ed Sheeran", "Colder Weather- Zac Brown Band"}; int yPos = 0, xPos = 50; Thread runner;
I am new to Java and have been learning it. I have a question here. I came across the following Java class and trying to understand it thoroughly but got confused how it is able to call an abstract method. Here is the code I am referring to :
package sampleapps.gui; import javax.swing.*; import java.awt.*; public class InnerClassAnimationExample { int x=70, y=70; public static void main(String[] args) {
[Code] ....
So, in the code above, there is an inner class NewMyDrawPanel which has a paintComponent(Graphics g) method. I have highlighted 2 lines of code above.
Line 1 : Graphics2D g2d = (Graphics2D) g; Line 2 : g2d.fillOval(x,y,40,40);
I understand we are type casting reference g to Graphics2D reference g2d and we are calling fillOval() method on g2d. I don't see a fillOval() method in Graphics2D class but it is there in Graphics class and fillOval method is an abstract method.
So, my question here is :
1. If we are not able to instantiate an abstract class(Graphics2D and Graphics classes), how are we able to access the fillOval() abstract method,
2. Secondly, since the fillOval() method is an abstract method, it does not have any implementation for the method.
However, when I call the method fillOval() on Graphics2D reference, I was able to draw and fill an oval of the specified co-ordinates. So, where would the actual implementation code be?
How do I create an instance of a class in a method?
I am a bit rusty whenever I think of instances. I always think of main method and objects when I see instance which gets me confused on what to do when I am not in a main method. The example:
I have a abstract class, School, and inside School I have some methods that must preform some action on an instance. For example, there is a move() method that must move the instance of School. Another method named, personOld(), which returns whether or not an instance of School surpassed some determined age.
I need to create an applet that displays a grid of command buttons which I have done. I then need to create a new class that draws a silly picture of an alien, which I have also done. Where I am completely stuck and confused, is that I do not know how to get the drawing into the applet. My code is below. I really do not fully understand why this is not working or how to get it working.
import java.applet.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class MartianGame extends JApplet implements ActionListener { DrawMartian aMartian = new DrawMartian(); DrawJupiterian aJupiterian = new DrawJupiterian();
I have been trying to get this code to work but in jGrasp it give the no main method, applet, or IMDlet. The assignment states: Design a class Message that models an e-mail message. A message has a recipient, a sender, and a message text. Support the following methods:
-A constructor that takes the sender and recipient -A method append that appends a line of text to the message body a method toString that makes the message into one long string like this:
"From:Harry Morgan To: Rudolf Reindeer. . ."
Write a program that uses this class to make a message and print it. package emailmodel;
import java.util.Scanner; public class Message { private String senderemail; private String receiveremail;
1 - I don't understand why I'm getting an empty stack error when calling the removecard method in my Table class line 13?
2 - I am trying to use a constructor to populate my deck of cards instead of a method when creating my theDeck object in my Table class line 11 but I get the following error:
java.lang.StackOverflowError at java.util.Vector.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source) at java.util.Stack.<init>(Unknown Source) at Deck.<init>(Deck.java:7) at Deck.<init>(Deck.java:34)
I'm writing a program that acts as a 'pocket' where the user is able to enter a kind of coin, such as, a quarter and the amount of quarters it has. I was assigned to do 3 different class, the Coin Class in which the coins and their values can be instatiated from, a Pocket Class, where I have to write a method that can add the coins of the user (basically the method would act like ArrayList .add() ) and the PocketClass tester. I have already written most of the code, but I am stuck as to how I could write the following method:
Java Code:
public void addCoin(String s, int i) { // s is type of coin, you are using s to instantiate a Coin and get value // i is number of coins, you are using i to keep adding value to the totalValuefor } mh_sh_highlight_all('java');
Would I use a for-loop in order to keep track of the number of coins? I would use ArrayList but the assignment calls for creating a method similar to that of .add()
How would I go about and make an enum, that has Strings and Methods?I want to make a class called GraphicalEffects, this class and be instanstiated and it has a method to apply graphicalEffects AS methods or some type of references to methods in an ArrayList.
If I have a method that creates a new variable (the name of which is a string argument for the method). Can I get that variable to appear in the workspace in the variables pane?
So instead of just using return to output the variable how do I get in that variables pane?
I am trying to create a method that takes an array of integers and prints it out using System.out.print. I'm having trouble creating the right way to print it out since I cannot find a way to convert the int array to a string to print it out.
public static String printArray(int[] num){ for (int i=0; i<num.length;i++){ String msg = num[i]; } return System.out.print(msg + " "); }
I am trying to create a method that reverses the digits of a number.
import java.util.*; public class KDowlingWeek7 { static Scanner console = new Scanner (System.in); //Scanner input = new Scanner(System.in); public static void main(String[] args) {
[Code] .....
The error I get is :
Error: cannot find symbol System.out.print(reverseDigit + " "); Symbol: variable reverseDigit Location: class KDowlingWeek7
How would I create a equals method to compare strings in a class that I'm creating. I need to create the method in my class, and then call it in a driver. How would I do this?
I am doing an assignment and I am clueless as to what I did wrong or supposed to do in terms of placement of coding.
This is what I supposed to do:
1.) Type the following shell for the class:
public class ParadiseInfo { }
2.) Between curly braces of the class, indent a few spaces and create the shell for the main() method:
public static void main(String[] args) { }
3.) Between the braces of the main()Method, insert a call to the displayInfo() method:
displayInfo();
4.) Place the displayInfo() method outside of the main() method, just before the closing curly brace for the ParadiseInfo class:
public static void displayInfo() { system.out.println ("Paradise Day Spa wants to pamper you."); system.out.println ("We will make you look good."); }
This is what I attempted to do:
I know it is wrong I am just clueless on where to put the code and why
public class ParadiseInfo { displayInfo(); public static void main(String[] args) { public static void displayInfo(); } system.out.println("Paradise Day Spa wants to pamper you."); system.out.println("We will make you look good."); }
--- Update ---
I also tried it this one and ended up with 1 error..
public class ParadiseInfo { displayInfo(); public static void main(String[] args) { } public static void displayInfo(); { system.out.println("Paradise Day Spa wants to pamper you."); system.out.println("We will make you look good."); } }
My jsp page needs to have a dropdown box. on selecting one/more than one values from this list, the same values get populated in another one.. we have a delete button too , it allows to populate the second box again.
The thing is i am to avoid scripts and use custom tags as much as i can...
