Link Objects And Calling A Variable Object Method
Jun 14, 2014
Say I have two classes, Author and Book, and I have 2 author objects and 10 book objects. I would like to know how to do two things:
1) Make some sort of connection that makes clear that author X wrote books A, B and F.
2) Call a method from a book object that is connected to an author.
Seeing as I don't know which books will be connected to an author, is there some way to call a method of an object bases on a variable object name? Something like call the getFirstPage() method for every book that is linked to author X?
View Replies
ADVERTISEMENT
Oct 27, 2014
I have a class for employees. This class has basic information for the employee but no real pay information. And 2 subclasses, one for employee's paid for hourly rates and one for those paid a yearly salary. Each subclass has their own pay() method, that calculates and returns their pay and extra fields relative to calculate that.
I'm just curious, if I do this and create an object for an hourly paid employee like so:
Object hourly1 = new HourlyEmployeeWilson("John Doe", "123 Tech Street",361961,"Human Resources", 0,12.50,50);
How can I utilize that classes public method of pay() to gather this instance (or hourly paid employee)'s pay? I've tried doing so via:
System.out.println(hourly1.pay());
But I get
DriverPayWilson.java:9: error: cannot find symbol
System.out.println(hourly1.pay());
^
symbol: method pay()
location: variable hourly1 of type Object
1 error
View Replies
View Related
Oct 26, 2014
When I try to call an object it can't find the symbol in the argument list. NetBeans says that it cannot find the movieCategory symbol when I try to call it. When I compile it to test a popup comes up that states "One or more projects were compiled with errors. Application you are running may end unexpectedly. I ran it anyways and everything runs up to the point of where it should call the object.
At this point it should get the Movie object and run the code within that, but if I put one of the categories it throws. "Exception in thread "main" java. lang.RuntimeException: Uncompilable source code - Erroneous tree type: <any>at MovieApp.main(MovieApp.java:33)Java Result: 1"
From my understanding to call an object it requires objectName.methodName(argumentList). Here is my Main method
/**
*This application will store a list of 100 movies and display them by category
*/
import java.util.Scanner;
public class MovieApp
{
public static void main(String args[])
{
//Displays <code>String</code> welcome message
System.out.println("Welcome to the Movie Application.");
System.out.println("There are 100 movies in the list.");
System.out.println("What category are you interested in?");
System.out.println();
[code].....
View Replies
View Related
Oct 26, 2014
I've been trying to learn Java for the last 36 hours or so (after applying for a HTML/CSS job saying "Java knowledge preferred"), and decided to experiment a bit making a graphical tic-tac-toe game. I eventually managed to get that done and it's working. Working code below:
[Java] tic tac toe 1 - Pastebin
So, it works to an extent, however, the way I am capturing which cell is selected seems very sloppy, and would not work if the cells weren't squares or rectangles. So I made a copy of the project and restructured it adding the mouse event to the cells, but now I can't get JComponent to repaint. New code below:
tic tac toe 2 - Pastebin
Curiously, clicking triggers the action for all 9 cells, but I presume it's because I haven't bounded them making it think I've clicked all 9 simultaneously.
What I've tried:
Make the Cell class extend the game class and call this.repaint()- causes stack overflow.
Calling Game.GameState() within the cell clicking event and making that function static - compiler doesn't like calling repaint() inside a static function.
Making another class to make a clone of the Game object and then refresh- was never going to work....
View Replies
View Related
Apr 4, 2015
This is what I have to create : Write a method that returns the largest object in an array of objects. The method signature is:
public static Object max(java.lang.Comparable[] a)
All the objects are instances of the java.lang.Comparable interface. The order of the objects in the array is determined using the compareTo method.
Write a test program in the main method that creates an array of ten Strings, an array of ten Integers, and an array of ten java.util.Dates, and finds the largest string (i.e. in the alphabetical order), Integer, and Date in the arrays.
Name your java class Max and your java file Max.java.
I am struggling a bit with this code as I am sure you can see, and am at loss. I have never used the compareTo method. Am I doing this right, or on the right track with my code?
public class Max implements Comparable {
public static Object max(java.lang.Comparable[] a) {
java.lang.Comparable tempObj = null;
for (int i = 0; i < a.length; i++) {
if (a[i].compareTo(tempObj) > 0)
[Code] ....
View Replies
View Related
May 20, 2015
In the process of creating a new class, I need to move my main method from the class SaveDate to the class DynamicTest. Below I have listed the code of both classes.The objective is to be able to run my program from the DynamicTest Class. I need understanding the process of moving my main method to a different class and creating an Object of a class and calling its method.
public class SaveData {
private static final Map<String, Object> myCachedTreeMap = new TreeMap<String, Object>();
public static final List<String> getLines(final String resourceParam, final Charset charset) throws IOException{
System.out.println("Please get: "+resourceParam);
if (myCachedTreeMap.containsKey(resourceParam) ) {
// Use the cached file, to prevent an additional read.
[Code] ......
View Replies
View Related
Oct 30, 2014
Alright, I don't understand how to link my compress method to my return statement method "getPText". Also in my compression I only want it to compress for 3 or more consecutive letters.
import java.util.Scanner;
class RunLengthCode {
String pText;
String cText;
void setPText(String PText) {
pText = "";
}
[Code]...
View Replies
View Related
Dec 14, 2014
I have two classes, MonsterGame (shown below) and Monster. Monster has a public accessor method to get it's private character variable, which represents the first character of the name of the Monster in question.
I'm just a bit confused as to why am I unable to cycle through the array of Monsters I have in the MonsterGame class and call
m.getCharacter(); (pretty much the last line of code)
public class MonsterGame{
private static final char EMPTY_SQUARE = ' ';
private char[][] gameBoard = new char[10][10];
private Monster[] monsters = new Monster[4];
private int maxXBoardSize = gameBoard.length -1;
private int maxYBoardSize = gameBoard[0].length -1;
[Code] ....
I understand that there need to be instances of objects to call methods, but is that not the case here? the Monster objects are have already been created, no? Do I need to create an index for the array? is the for loop not enough?
View Replies
View Related
Nov 6, 2014
I don't understand why the object reference variable 'a' cannot be recast from a thisA object reference to a thisB object reference.Is it the case that once a reference variable is linked to a particular object type then it cannot switch object types later on.I am facing the Java Associate Developer exam soon and I am just clearing up some issues in my head around object reference variable assignment,
class thisA {}
class thisB extends thisA { String testString = "test";}
public class CastQuestion2 {
public static void main(String[] args) {
thisA a = new thisA();
thisB b = new thisB();
[code]....
View Replies
View Related
Sep 21, 2014
I hope I'm putting this question in the right folder. I have an array of objects, and I have defined a setter for a variable in the object. When I call the setter, I get a NullPointerException. Here is the relevant code for the object.
public class Digit extends Thread {
private int digit;
public void setDigit(int digit) {
this.digit = digit;
}
// run method follows
}
Here is the portion of the main class where I define an array and then call the setter.
Digit[] digits = new Digit[10];
for (int i = 0; i < digits.length; i++) {
digits[i].setDigit(i); // NullPointerException occurs here
}
View Replies
View Related
Feb 3, 2014
eg: "Sourdough".toUpperCase();
I guess this is actually a 2-part question:
- How does this work? (nothing seems to be passed through the parameter, so how is it that the value or variable is manipulated in this fashion?)
- How would I create a method that does something similar? (ie. adjusting a variable without having it passed through the parameters)
View Replies
View Related
Oct 23, 2014
I am trying to call a private method to another method that are located in the same class.
I am trying to call prepareString to the encode method below.
Java Code:
public class ShiftEncoderDecoder
private String prepareString(String plainText)
{
String preparedString = "";
for(int i = 0 ; i < plainText.length();i++)
if(Character.isAlphabetic(plainText.charAt(i)))
[Code] .....
View Replies
View Related
Apr 6, 2015
How do I take the union between an object called on and the object passed in the parameter?I have an interface:
Java Code:
import java.util.Set;
/**
* An extended Set where additional functionality is added
*/
public interface NewSet<T> extends Set<T> {
[code]...
Now, the union method requires a NewSet object to be called on. The Union will be performed between the object called on and the object passed in the parameter, which is set.How do I call on a NewSet object in order to take the union between the object called on and the object passed in?Do I just do:
Java Code:
public NewSet<T> union(NewSet<T> set) {
NewSet<T> calledOn = new ArrayList<T>();
// ...
} mh_sh_highlight_all('java');
View Replies
View Related
Feb 23, 2015
I am working on a project and it asks me to "Provide appropriate names and data types for each of the instance variables. Maintain two GVdie objects" under class fields. I am unsure as to what is being asked when asking for two objects as instance variables and how I would write that...
View Replies
View Related
Apr 2, 2014
I am trying to simplify my constructor by using "this" reference variable. I am aware how to use this reference when making constructors that involve fields of primitive data types; however, not so sure fields involving objects. I have made the following constructors and haver placed a question mark in the last parameter. How I can use this reference that involves objects.
public class RetailItem
{
//Create the fiels for item.
//You need item name and item number. then you would need
//cost
private String description;
private int Item_Number;
private CostData cost;
[Code] ....
View Replies
View Related
Jan 26, 2014
The idea is to create a program to add plants and retrieve plants from a Nursery. I created a class with the properties of the plants and also there is the class an Array list to keep track of the plants entered ( they will have to be printed later) (I am not too sure if adding a public class there is the best option.
The program will allow the user to pick and action and from there the code will do something. I don't want to have all the code inside 'main' The problem is in line 114.This is what I have so far.
Java Code:
package plant.nursery;
import java.util.ArrayList;
import java.util.Scanner;
/**Class to create a plant for a nursery.
public class PlantNursery
[code]....
View Replies
View Related
Oct 23, 2014
I need to get the string encodedString from the method encode able to be used in the decode method.
Java Code:
public String encode(String plainText) {
int prepareString;
int shiftChar;
String preparedString2 = prepareString(plainText);
String encodedString = "";
for(int c = 0 ; c < preparedString2.length();c++)
[Code] ....
View Replies
View Related
Aug 8, 2014
I have a line code like this one:
String result = someHeavyMethod();
and I need to add this logic: "if the method doesn't finish within 10 seconds, cancel it and let me continue with the rest of the program".
View Replies
View Related
Apr 8, 2014
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();
[Code] .....
View Replies
View Related
Sep 15, 2014
I am calling a method from within a class like so:
xmlWriter.updateFile(environment, doc);
The class is xmlWriter & the method is updateFile
updateFile passes Environment environment (another class) and Document doc (document builder)
but I am unsure about it passing these through the parameters in the method call..is it correct?
Also underneath that method call for the update could I then do another method call for the export method of the file?
View Replies
View Related
Mar 24, 2014
I am having problem to call a method from another class using arrays. I already know how to call a method without using arrays but I am not sure how to pass parameters to the main method using arrays. I'd really appreciate any feedback or comments!This is what I have so far.
public class Customer123 {
public static void main(String [] args){
Scanner input = new Scanner(System.in);
int x;
System.out.print("Total number of customers: ");
x = input.nextInt();
[code]....
View Replies
View Related
Nov 17, 2014
I'm trying to call a method to my main method, but I can't seem to get it to work and it keeps resulting in a compile error.
import java.io.*;
import java.awt.Point;
import java.text.DecimalFormat;
import java.util.Random;
public class Chase {
public static void main(String args[]){
[Code] .....
View Replies
View Related
Sep 10, 2014
I have been reading about methods and I do have a beginner level understanding on how they work. I was trying to mess around and make a dog calculator using methods. I ran into a small snag; I cannot get the method to call to the main or the program to compile correctly. The first code below is the original. To me it looks like (based off of some examples I looked at) there should be no problems, but NetBeans gives me a few errors. 1) line 8- "cannot find symbol, variable dogYearCalc; 2) line 18 illegal start of expression; and 3) line 22 - unreachable statement.
import javax.swing.JOptionPane;
public class KrisExample {
public static void main (String[] args) {
double dogYears = 0;
JOptionPane.showInputDialog (null,"Please enter you dog's age in human years:");
[Code] ....
Someone told me that I was calling dogYearCalc without any arguments in your main method. I take that to mean that I needed to add it to the main, so I did here:
public static void main (String[] args, double dogYearCalc) {
That got rid of my first error, but then when I tried to run the program NetBeans said that I have no main class, so switched back to the original program above.
I thought that when I calling the dogYearCalc method on line 10 was the whole purpose of using a method. It seems to me that putting it somewhere in the main is counter productive.
View Replies
View Related
Mar 6, 2015
calling a method from one class to another.I have two classes. One called Vacation and another called VacationDriver.I am trying to input an int for addVac and have the value update to the numSold within the updateSales() method in Vacation. From there it should update and display in the v1.toString in the VacationDriver.
Vacation
import java.text.NumberFormat;
public class Vacation {
private String vacationName;
private int numSold;
private double priceEach;
[code]...
View Replies
View Related
Jul 28, 2014
Can we recall the main method? I'm trying a code to recall main method (after the calling of JVM). I know this doesn't make any sense but I'm trying this just like that.
Code:
class derived {
public static void main(String args[]) {
System.out.println("Main Method class");
show();
}
static void show()
[code]....
View Replies
View Related
Apr 13, 2014
I have a JSP page that calls a Java method .. using GlassFish 4.0 it worked just fine, now I'm trying to run it on a new server with Tomcat 6.0 but it keeps giving me this error: "the function result must be used with a prefix when a default namespace is not specified"
Here's my JSP page:
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
......
<jsp:useBean id="diskUtilData" scope="request" class="newpackage.ResultPage" />
.....
<c:forEach var="celldata" items="${diskUtilData.result()}">
[Code].....
View Replies
View Related
