Loop Through Objects And Call Method For Each One
Nov 22, 2014
I want to loop through each of my objects and call the method for each one. ( polymorphic array )
Error: Constructor Dog in class Dog cannot applied for gives Types
Required String,String
Found: no arguments
Reason actual and formal argument lists differ in length
Java Code:
public class animal {
private String m_type="";
private String m_name="";
public static void main (String[] args) {
[Code] ....
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Apr 15, 2015
if some of you worked with Unity Game engine (C#) the idea is that game has main loop and once per cycle it call for example Update() method in all objects which implement certain interface.
I would like to repeat such pattern in Java for another another program, not even game related, but I would still need a main loop and event driven behaviour with async call backsSo question is how to implement the fallowing scenario:
Imagine i have interface which implement some methods and one of them is Execute()
I have the main controller class which implement main loop, also multiple other classes which implement the same interface with method Execute(). How can i call this Execute() method on all objects which implement that interface each loop cycle?
Should i keep and track reference of each object which was implemented with this interface and go through inner "for" loop trough each reference and call manually Execute() method in each of them?what if each object implementing interface have to run Execute() method simultaneously? in parallel independent from each other?
Referring back to Unity engine and their Update() method - there is exactly the same situation:you can have multiple objects with script attached, thats script implement interface which has multiple methods and one of them is Update() and once per cycle all objects with that Update() method will be executed in parallel independently
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Feb 13, 2014
I am just trying to test this array, for a locker combination program that involves classes...but the array is printing out the whacky numbers for the location. When I try to call the method in the main, it does not work. How do I call a method that exist within a class into the main method?
public class locker {
public static void main(String[] args) {
CombinationLock();
[code]....
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Dec 2, 2014
I have been baffled by the functioning of repaint() - and the SwingPaintDemo3 with the moving square seems mysterious - you call repaint(x,y,w,h) twice and the first time it clears the clip area and the 2nd time it paints the red box. The code in paintComponent tells it to paint the box both times, yet somehow it ignores the initial box and only paints the 2nd one.
I've been writing code to bounce some balls in a box to try and understand the behavior. I set up an array of ball objects, loop through them, move them adjusting for collisions with walls and each other, then repaint(). I call repaint x2 for each ball, just like in the example. In my paintComponenet code, if I try to just paint the current ball only one ball will move, even if I send a different ball object each time. The only way to get all the balls to show up is to put a loop in paintComponenet that goes through all 100 balls every time I call it. I was worried that to move 100 balls I was painting 100x100 times.
So I put some System.out.println commands in my ball move loop, inside my object ball draw commands, and inside the paint component.
private void calculateMoveBall(BoxBalls oneBall) {
System.out.printf("
Entering calculateMoveBall [%1$2d]
",
[Code].....
So even though I called repaint() 200 times (twice for each ball), repaint was actually only called once, drew all the balls at once, and then went back. And I just noticed it appears to have waited until I exited the calculateMoveBall loop to go into paintComponent! The spooky things is how does it know to do that? Does the Java machine 'see' that it is inside of a loop, and perhaps also sees the loop inside of paintComponent, and somehow correctly guesses that it doesn't have to do it 200 times, but can wait and do it once? If I attempt to do the same thing in code, take the loop out of paintComponent() and call repaint() with the current ball, expecting the machine to do exactly what I tell it, it refuses and does it's own thing, waiting to call paintComponent on the 100th ball, drawing only the last ball (so I guess the loop inside paintComponent is not in the logic).
So a call to repaint() is a request for a higher being to decide if it has the time or energy to repaint the clip. If not, it ignores the call, or stacks them up for later (maybe I should try a million and see if it has room for that!) - well so far up to 4000 it behaves the same. This is useful if you are happy with "this is how it works so use it that way". However I really don't like having some kind of hidden logic that I have to trust to work the right way. If I don't want it to wait until later I'm not sure what to do. And I don't trust the machine to do whatever whenever. How do you debug that???
Questions: Is there documentation to know what repaint() will do or how it decides when to call paintComponent? The Swing tutorial gives the example but not the why. "By now you know that the paintComponent method is where all of your painting code should be placed. It is true that this method will be invoked when it is time to paint" "An important point worth noting is that although we have invoked repaint twice in a row in the same event handler, Swing is smart enough to take that information and repaint those sections of the screen all in one single paint operation. In other words, Swing will not repaint the component twice in a row, even if that is what the code appears to be doing." (What the code appears to be doing - now we have to guess what it is doing)
Is there a way to force repaint() to call paintComponent on a clip rectangle (not just on the whole thing?) I would think invalidate() would force repainting of the whole componenet.
Perhaps this is when you draw to a bitmap in memory and paint the whole thing on the screen...
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Sep 29, 2014
I've never had to do a void method call. I have my void method in one class and my main (where I want to do the call) in another. How do you actually call a void method?
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Feb 12, 2014
Is it possible to use a loop to create objects? I'm trying to put together a program (just as a way of learning) to run a horse race.
What I'd like to is have the user enter the number of horses they want in the race, and then create the objects as the user enters the various attributes of the horse (at least the horse's name), and then once all the instance variables have been set, create the first horse object and then move on to the second one, etc, until all the horse objects have been created.
I know I can't use something like a for loop to do it, so how would the code be writte
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May 18, 2014
How to call/define/describe self method.. below is my code :
Java Code:
public static void main(String[] args) {
banana1();
banana2();
banana3();
banana4();
banana5();
banana6();
[code]....
how exactly to call a self method ?
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Oct 3, 2014
My code has a method where the users input a bunch of variables and then those variables get added together in a new variable. What I want to know is how do I call the variable that is in the other method to another method?
import java.util.*;
public class Calc{
public static void main (String [] args){
determinevalue1();
determinevalue2();
determineTotalvalue(double value1, double value2);
[Code] ....
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Dec 6, 2014
I am trying to get the program to ask the user to enter the project grade and if it is less than 65, then I want the program to display "fail" or if it is greater than 64 than I want it to display "passed". In this project I have to include a method and I am trying to call it in my if-else statement. I keep getting an error message saying "Project.java:143: error: incompatible types: void cannot be converted to int". I posted my code below. It's a long program, but this part is toward the bottom.
import java.util.Scanner;
public class Project {
public static void main(String[] args) {
//call method
welcomeMessage();
[Code] ....
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Oct 30, 2014
I have two comboBoxes - one in main and another in my 'windows' class. The code below is in main and references the comboBox in main but I need to use the comboBoxEnv out of my 'windows' class. How can I do that so it says ComboBoxEnv rather than comboBox?
JMenuItem menuExport = new JMenuItem("Export");
menuExport.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(comboBox.getSelectedItem() == null){
[Code] ....
I've gotten access to it by changing my code and making a method of it but I'm not sure of what I do now
exportImport.comboBoxEnv();
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Jun 9, 2014
How do i call the method without using inner classes in this example:
jt = new JTable (model) {
public boolean isCellEditable (int row, int col) {
if (col == 5) {
return false;
[Code] ....
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Apr 28, 2014
I am trying to call a java method in jsp. The main idea is to hide menu based on the user who logs in. The java class flows like this :
public class UserVerification {
public static void main(String[] args) {
UserVerification obj = new UserVerification();
System.out.print(obj.GetUserVerification("abc"));
[Code] ......
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May 26, 2015
I have the following:
public class HistoricalMoment{
private String eventName;
private ClockDisplay timeOfEvent;
public static final int MIDNIGHT_HOUR = 00;
public static final int MINUTE_ZERO = 00;
}
How can I create a method called public void addMinuteToTimeOfEvent() which calls the timeOfEvent's increment() method to add one minute to the timeOfEvent?
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Apr 3, 2014
The main method should creates a Student object with name as "Bill" and marks as {88,92,76,81,83} and print it.
Java Code:
class TestStudent {
public static void main(String args[]) {
Student1 st = new Student1();
st.name = "bill";
Student st1[] = new Student[6];
//This gives error
st1[].marks = {1, 5, 8, 9, 7, 6}; mh_sh_highlight_all('java');
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Oct 13, 2014
This assignment requires me to show areas of each shape by using loop. I can do it with abstract and interface , but in this case. I don't know how to use method getArea() to loop for each object
import java.util.ArrayList;
public class TestShape {
ArrayList<Shape> list = new ArrayList<Shape>();
Circle c;
Rectangle r;
Square s;
public TestShape() {
[Code] .....
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Oct 4, 2014
I know the normal way of naming objects is
Pipe pipe1 = new Pipe
but I want the objects to be made inside a loop and named after how many times the loop have been gone through so I tried
Pipe pipe(numberOfTimes) = new Pipe
where numberOfTimes was a variable counting the loops. This is not working.I need the naming to be pipe1, pipe2, pipe3 etc depending on how many times the loop have been pased
Scanner keyboard = new Scanner (System.in);
String morePipes = ("yes");
int dimRor;
int numberOfPipes = -1;
[code]....
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Jul 8, 2014
I have a problem with my application. It supposed to store 4 different Room objects but when I entered one only it stores tat object variables into all my Array elements. I just need it to store any number of objects as long as it is less than 4.
Java Code:
import java.util.Arrays;
import java.util.Scanner;
import javax.swing.JOptionPane;
class TestRoom {
public static void main(String [] args)
{
String[] roomsInHouse = new String[4];
[Code] .....
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Jan 3, 2015
I am currently drawing graphics onto a JPanel, by overriding the standard paintComponent method.
Is it possible to call a method to draw some predefined shapes, instead of filling this method with all the stuff I need drawn, and if so, how do I do that?
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Sep 3, 2003
I want to call the HEAD method on a servlet.If in my HTML code, I specify -
<form name="testHead" action="/servlet/servletName" method="HEAD">
And the servlet handles the HEAD method in the sense that the doGet() method returns if the method type is HEAD.When I run it, the servlet returns the code returned by the entire doGet() method. This shows that the doGet() method does not realize that it is a HEAD method and it should return back without processing further.The application server is Tomcat 4.0.
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Mar 6, 2014
I am writing a program to take user input in order to create an array, then call a void method that will read in the numbers (from user's input) and fill the array.This method must use a loop to do this.(The array is to be passed to the void method as a parameter)
in theory, this should change the contents of the array, but without returning a result. Because it is a void method, the array is only passed through the method, not returned; Am I correct?How can I return the array and display it without having to change my method type?
Here is my code:
Java Code: package program7array;
import javax.swing.JOptionPane;
public class Program7Array
public static void main(String[] args) { // main method
int howMany = Integer.parseInt(JOptionPane.showInputDialog(null, // user decides how long array is
"How many numbers are there?"));
double [] numbersArray = new double[howMany]; // creating the array
makeArray(numbersArray, howMany); // calling the array
[code]...
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Oct 11, 2014
my arraylist is declared in my main method. A string that i will be calling on is declared in my main method as well. The arraylist and string is passed to a method outside the main. I am to search for the beginning of a string and end of the string, remove those items. Then i am to pass the string with the removed items to arraylist that is called in my main with an enhanced for loop. The for loop then displays what is needed from the string and the method i created. I will posting an example of my main and method that is used in my program.
public class ExampleUrl {
public static void main(String[] args) throws MalformedURLException, IOException {
ArrayList<String> urlList = new ArrayList();
String url = "";
[Code].....
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Mar 4, 2014
I used java and jsf. I created dynamic datatable in java file. Can i call java method from setOnchange() event?
I am able to call java script function from setOnchange() event. See the below code which is working fine for java script.
HtmlSelectOneMenu selectOneMenu = new HtmlSelectOneMenu();
selectOneMenu.setStyleClass("dropdownStyleTwo");
selectOneMenu.setOnchange("openWin(this);IGNORE_UN LOAD=false");
I wrote openwin() function in java script. But i am not able to call java method change().
Code which is not working.
HtmlSelectOneMenu selectOneMenu = new HtmlSelectOneMenu();
selectOneMenu.setStyleClass("dropdownStyleTwo");
selectOneMenu.setOnchange("myclass.change();IGNORE _UNLOAD=false");
myclass is the bean of class Test. If user select any value from dropdown i want to call change java method. This function will apply the same selected dropdown value to the other record also.
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May 7, 2015
I can call a child method from a main method. If I have a parent called "Assessment", a child called "Quiz", and another child called "test". Can I instinate an object like Assessment a = new test(); and call a method in test.I know the method can be called if I instinate the test t = new test() but that defeats the purpose of inheritance which I'm learning in class.
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Feb 18, 2014
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?
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Apr 21, 2014
In an JEE6 webprofile project, using JBoss EAP 6.1:
I have a CDI Bean:
import javax.faces.bean.SessionScoped;
import javax.inject.Inject;
import javax.inject.Named;
import de.dpunkt.myaktion.model.Organisator;
import de.dpunkt.myaktion.services.OrganisatorDAO;
[code]....
When I call doCreate() I get
javax.servlet.ServletException: javax.ejb.EJBAccessException: JBAS014502: Aufruf an Methode: public abstract void de.dpunkt.myaktion.services.OrganisatorDAO.save(de.dpunkt.myaktion.model.Organisator) von Bean: OrganisatorDAOBean ist nicht gestattet
javax.faces.webapp.FacesServlet.service(FacesServlet.java:606)
which translates to: call of method: .... from Bean ... is not allowed
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Sep 7, 2014
I want to set an html text on al label, but also call a method.
I tried:
Java Code:
scoreMens.setText("<html>joejoe<BR>jaja<BR</html>" + naamSpeler.laatKaartenZien()); mh_sh_highlight_all('java');
But the naamSpeler.laatKaartenZien(), which returns a string, doesn't show on the label. Is there a way to call a method and use a html text on a label?
The name of the thread should be "call method in html text on label"
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