Constructor Error When Extending A Class?
Oct 21, 2014
I am writing a program that should take a url and scan the page for any links. It is in the beginning stages, but I ran into an error when I tried to extend a class. There's a lot going on in this code, but the error is caused by the constructor.
Error message at compile time:
"constructor Page in class Page cannot be applied to given types;
{//Constructor
^
required: String
found: no arguments
reason: actual and formal argument lists differ in length".
Here's the code(first my class, then the class I extended)
public class SearchEngine extends Page {
public static Color customGreen = new Color(69, 194, 33);
public static Color customYellow = new Color(232, 166, 12);
public static Color customBlue = new Color(25,97,255);
public static Color customYellowComp = new Color(178,125,0);
[code]...
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Jun 12, 2014
I'm getting an error on line 51 and don't know what it means?
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package million;
import java.util.Scanner;
import java.util.ArrayList;
[code].....
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Jul 3, 2014
I am working on a project involving a class that has the attributes of one of its inner classes. Now, if possible, I would like to make it so that the inner class is not visible outside of the class. Also, some of the functional mechanics require that the class be an instance of the nested inner class (it extends the inner class). The following code snippet demonstrates the situation.
public class A extends A.B {
public static class B { //ideally I would like this to be private/protected.
}
}
When I try to compile this program, I get the error message "Cyclical inheritance involving A." This error does not make much sense because, since the inner class "B" is static, it requires no instance of "A" (it does not inherit from "A" or uses it). My question is "Is it possible to do something similar to this structure?" I have searched many forums in search of the answer but have not found anything that attempts to explain it. The closest problem that I have found is one relating to the inheritance of a nested inner class from another class. I would like to express that the problem that I am having involves a class defined within the inheriting class.
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Oct 18, 2014
What is the difference between extending JFrame in one class and simply constructing a new JFrame object in that same class? What benefits do I have with each solution, providing I want to use that class to create the GUI. Is it the same or are there differences rather than not having to reference to a new JFrame to be able to use its functions?
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Apr 26, 2014
I've been trying to pull data from another class file "Calculations.java" and have it be displayed in a TextField in "DataAnalyzerGUI.java". Here is how the hierarchy is broken down for my assignment:
DataAnalyzerGUI.java extends JFrame
ReadFiles.java extends DataAnalyzerGUI.java
Calculations.java extends ReadFiles.java
Everything displays and functions correctly in a command prompt if I use a line like this:
System.out.println ("Lowest opening " + dateArray[lowestOpenIndex] + ": " + dataArray[lowestOpenIndex][2]);
But trying to get it to display in a GUI has been quite troubling.
I know the code is supposed to look something like this:
dataOutput.setText(DESIRED CODE HERE);
But I am unable to find anything of value to work out.
I have attached my complete project....
Attached File(s)
Assignment 4.pdf (247.05K)
Assignment 4.zip (235.81K)
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Aug 28, 2014
can we pass private final class object to another class constructor?
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Aug 1, 2014
So i declared a class in main class but it seems there's error when i compile:
constructor xx in class xx cannot applied to given types
This is my java class:
public class trainer extends person{
String classType;
public trainer(String name, String gender, String address, int id, String classType) {
super(name,gender,address,id);
this.classType=classType;
[Code] ....
And this is the way i declared in main class:
trainer tr = new trainer();
And what i want to do is:
tr.toString();
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Oct 27, 2014
So I am working on a school project and I have 2 classes, class FakeGravity contains all the properites and class BouncyBall is my driver class. For some reason when I try writing
FakeGravity gravity = new FakeGravity( );
I get an error. I am attaching an image of the error, and also attaching the program just in case you need more information. Also I was using blueJ to write the program
dcasarrubias, on 27 October 2014 - 02:44 PM, said:
So I am working on a school project and I have 2 classes, class FakeGravity contains all the properites and class BouncyBall is my driver class. For some reason when I try writing
FakeGravity gravity = new FakeGravity( );
I get an error. I am attaching an image of the error, and also attaching the program just in case you need more information.
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Feb 7, 2014
I've a parent class with a argument constructor like below(a sample code)
public class Parent {
Parent(String name) {
System.out.println(name);
}
public static void main(String[] args) {
}
}
Also I've child.class which extends Parent.class as shown below,
public class child extends Parent {
child(String name) {
super(name);
}
}
Now, I want create/modify the constructor which is in child, by taking "int i" as an input instead of "String name". How can I do that? Run time I want to execute child constructor not a parent constructor.
Condition is: Without making any changes to the Parent class
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Oct 18, 2014
I am trying to create an array where each object includes a service description, price, and time in minutes. I have a Service class and a SalonReport class:
import java.util.*;
public class Service
{
public String serviceDescription;
public double servicePrice;
public int timeMinutes;
[Code] ....
When I compile this, I get an error message that says:
SalonReport.java:8: error: constructor Service in class Service cannot be applied to given types;
salonServices[0] = new Service("Cut", 8.00, 15);
^
required: no arguments
found: String,double,int
reason: actual and formal argument lists differ in length
What this error message means and how I can correct it? I am confused because my SalonService() method has (String service, double price, int minutes), and each object is listed in that exact order.
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Jun 23, 2014
Do we have constructor in abstract class? If we have then what is the use of it?
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Feb 13, 2015
This code works
public class RedShapeDecorator extends ShapeDecorator {
public RedShapeDecorator(Shape decoratedShape) {
super(decoratedShape);
}
Below results in an error
public class RedShapeDecorator extends ShapeDecorator {
protected Shape decoratedShape;
public RedShapeDecorator(Shape decoratedShape) {
this. decoratedShape=decoratedShape;
}
So I am guessing that if you extend class, you should use super to pass objects?
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Jan 7, 2014
When creating a class with a constructor, why does one have to create private variables (attributes) to be used as parameters by the object? The object's parameters will be set to be exactly equal to the private variables (attributes), so what is the point of having the private variables (attributes) Why are both private variables (attributes) and parameters needed when they are set to be equal each other anyway?
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Feb 4, 2015
Below Code
abstract class A
{
A(int a, int b)
{
}
}
If we can't create objects for abstract class, what is the need of writing constructor???
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Nov 5, 2014
How do you test a default constructor in one class and then test it in a different class? This is the code for the Person class which has the default constructor. I'm not sure in the PersonTester class how to access this default constructor and how to test it - what I have so far for the second class is also below.
class Person {
// Data Members
private String name; // The name of this person
private int age; // The age of this person
private char gender; // The gender of this person
[code]...
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Jul 15, 2014
I am following this article : [URL] ....
It is important to note that the inference algorithm uses only invocation arguments, target types, and possibly an obvious expected return type to infer types. The inference algorithm does not use results from later in the program.
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Feb 28, 2014
The one problem in my book was to create a constructor for different shirt features, which I did and ran successfully. Out of curiosity, I also added other methods to see if it would run if the parameters were different from the constructor. It keeps giving me a constructor error. So, my question is, am I able to create a class that uses a constructor with parameters and other methods without errors? I'm guessing there's no reason to since it would be wasted space since the constructor could do it but was just curious if it's possible.
Is everything from the constructor down (in the class) and Shirt.oneShirt (in the main) just a waste of time?
Here's my example:
public class Shirt//class name.
{
int collarSize;//data field.
int sleeveLength;//data field.
int pocketNumber;//data field
public final static String MATERIAL = "cotton";//final data field for material.
public Shirt(int collarSize, int sleeveLength, int pocketNumber)//start of constructor.
{
[Code]...
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Jan 6, 2015
I have two classes LightController & Circle. I need to use the LightController class to do the following:
Creates an instance of Circle with a diameter of 50 and a colour of OUColour.GREEN and assigns this new circle to the instance variable light.
Sets the xPos of light to 122.
Sets the yPos of light to 162.
I am struggling to write the correct line of code to set the colour to green and set diameter to 50.
Code for the two classes below.
001
import ou.*;
002
import java.util.*;
003
/**
004
* Class LightController
005
* This class uses the Circle class, and the Shapes window
[Code] ......
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Mar 8, 2015
I have a class of Date with a constructor with 3 parameters in it. Those 3 parameters are int data type just to enter month, year, day.
I have another class called Author which has a constructor of Date diedDate; as a parameter passing to the Author constructor.
I was asked to call the Date parameter is null, call the default constructor but I thought for the Date parameter I could only enter something like 0,0,0 instead of typing in null, null, null because null is for String data type isn't it?
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Mar 12, 2014
I've a vertical-bar-delimited file where most elements contain text, some contain whitespace, and some are empty. Examples:
62RG|fe|Pencil Financial Group, LLC||doug@pencil.com|||85637889|Cross, Ben|bcross@godaddy.net|Bernard|Cross|Ben||315 One Tree Hill Terrace|Lafayette|LA
62RG|fe|Pencil Financial Group, LLC||tracy@pencil.com|||13658734|Dustin Cardwright|dcart@motorola.com|Dustin|Cartwright|||| |LA
which I parse and store with
String str_arry = innline.split( "|", 17);
lisst.add( new Contact( str_arry));
and my Contact class has the constructor
public Contact( String[] str_arry) {
for( int ii = 0 ; ii < str_arry.length ; ii++ ) {
if( str_arry[ii].matches("^s+$")) {
str_arry[ii] = null;
System.out.println("hit a null");
[Code]...
I expect the for-loop in the constructor to find any elements containing whitespace characters and set them to null for subsequent assignment.And when the code runs I do see some hit-statements pop up, so the detecting part is working.
But when I then process the list and access a Contact object and test fields for nulls I don't find any ie
if( aContactObj.getfFCity() == null) System.out.println("city is null");
never prints when it should.
What's the trick? Or is my approach wrong and if so what should it be?
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Mar 4, 2014
Instructions
Create a WordCounter class with a constructor that takes a file name as a parameter
The class should have two fields: one for the file name and one for a HashMap to store word count information
The constructor should call a private method, countWords, that reads in the file and counts the word frequencies
The class should contain a get method for each field, as well as a print method that prints out the map in the following format:word:frequency
When printing, the map should be sorted by either the word order or frequency (Hint: see Collections.sort)
You should include the sample text file on Blackboard. This is what i got so far
Java Code:
import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Scanner;
public class WordCounter
[Code] ....
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Jul 5, 2014
I am working on a program that simulates a bug moving along a horizontal line, My code works correctly when I test it in it's own class but when I tried testing my constructor and methods in a test class I received an error saying, "package stinkBug does not exist" on lines with my methods. However, stinkbug is not a package.
Java Code:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
[code]....
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Jan 8, 2014
I've 3 classes.
1. Circle
2. GetInputFromUser
3. testCircle
package ABC;
public class Circle {
private double radius;
public double getRadius() {
return radius;
[Code] .....
In the testCircle class, in the line: getRadius = ui1.GetInput();
It's showing the error: The method GetInput(float) in the type GetInputFromUser is not applicable for the arguments ()
And when I do: getRadius = ui1.GetInput(rad);
It's showing the error: rad cannot be resolved
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Jul 25, 2014
Really need some simple and complete example on how to extends components (graphically and functionally) for primefaces 5.
For example I can't figure how to add custom attributes to existing component or define default values for existing attributes.
Is there any tutorial or a basic common way to achieve this goal or each component have to be extended in its way?
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Jan 30, 2015
My teacher told me : It looks like everything is working except that in the Box, the method returns true if it is not a box.
The only other thing missing is the if statements in the main method using the .equals() method to do the comparisons. But, now I am lost on how to do my if statement.
HTML Code:
private int height;
/**
* Constructor for objects of class box
*/
public Box3(int l, int w, int h)
{
// call superclass
super(l, w);
// initialise instance variables
height = h;
[Code] ....
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Sep 20, 2014
Basically I want to make a class called library, but I don't want to make an interface because I actually want to define the methods. I think I can only use abstract classes but not really sure how to use those. But I still have a problem, I want to create a Map that classes implementing Library class have to have in their code, and the Map will be a HashMap with <String, ParentClassHere>, so basically let's say I make a class called Car, implemeing Library to the Car class would create a Map library = new HashMap<String, Car>. Can I do something like this? And also include methods to get values and set values to the library Map?
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