Is there anything wrong on my code?
import java.util.*;
public class Card
{
private String description;
private String suit;
private int value;
private static final String [] cardName {"Ace","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten",
"Jace","Queen","King","Joker"};
[Code]...
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 RelatedLet's pretend I'm working on an RPG. Like in all RPGs, there are items found all throughout the imaginary world. Each player and NPC can obtain an item. My question will concern those items.
In other words, I'd like to use instances of a class in multiple places of the code. Each instance will have its own, individual values of instance variables, with one obvious exception: itemQuantity should have a different value in playerInventory, npcInventory, etc. Also, I'd like a list of all items that can be found in the game. This list doesn't need itemQuantity at all.
class Items {
String itemName;
float itemWeight;
int itemQuantity;
[Code] ....
The question is: should I really make itemQuantity an instance variable of the Item class? It seems as though for each copy of the Item class I should create a separate copy with different value of itemQuantity, but that's not very efficient. Where is the error in my logic?
What's important is that there may be plenty items in a game and a player may be given power to create new items during the course of the game.
I'm just wondering why variables in interface can't be instance scope?
interface Test{
int a;
}
And then
Test test = new TestImpl();
test.a=13;
Yes, it violates OO, but I don't see why this is not possible? Since interface is not an implementation, therefore it can;t have any instance scope variable. I can't find the correlation of interface being abstract and being able to hold instance scope variable. There's gotta be another reason. I'm just curious about any programmatic limitation, not deliberate design constraint. the example of programmatic limitation is like when Java forbids multiple inheritance since when different parents have the exact same method, then the child will have trouble determining which method to run at runtime.
Alright, I have a JavaFX gui that is creating a new instance of data calculation to graph in a chart; however, the data is not updating each time the Platform.runLater() feature executes. Each time an event occurs, a new instance with the same variable name occurs. I use to get methods to retrieve the data I want, so shouldn't the values update each time the new instance is created? This is a very condensed version of what happens with the event, but this is what is not working correctly.
Event:
solarPlot = new SolarTracker();
solarPlot.getElevation();
solarPlot.getAzimuth();
Class constructor :
public SolarTracker() {
[Code] .....
I'm having trouble to fully understand the difference between instance and class variables.
I though it was all about the static, i.e:
int age; // instance variable
static int age; // class variable
What's behind this?
Implementation that proves that instance variables are not thread safe ....
View Replies View RelatedI am having a small JavaFX program where I try to set a value to TextField. Below is the part of FXML file and highlighted is the Textfield ....
fxml file
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="185.0" prefWidth="598.0">
<children>
<TextField fx:id="actiontarget" editable="true" layoutX="146.0" layoutY="73.0" prefWidth="198.0" text="" />
[Code] ...
I want to display a string value to that text field.
So, I am using that fxid (actiontarget)
But actiontarget.setText (pathofFile) is not working .
Nothing displays and no value sets for the Text field.
How can I set value in that text field through above code.
GoodEmployee is defined who has ALL the following properties:
He should be married.
He should have 2 or less than 2 children.
His middle name should start with "k" but not end with "e"
The last name should have more than 4 characters
The character "a" should appear in the last name at least two times.
The name of one of his children should be "Raja"
Write a method:
boolean isGoodEmployee( boolean isMarried, int noOfChild , String middleName , String lastName , String[] childNames);
isMarried true if the employee is married.
noOfChild the number of children of the employee.
middleName the middle name of the employee
lastName the last name of the employee.
childNames the array of the names of the children of the employee
I have a class named Base and a private variable named _hopcount i have 10 instances of class base i use _hopcount as creteria to some if but other instances edit _hopcount so i want to prevent _hopcount edit by other instances; I want to have private variable which other instances of same class can't modify it.
public class Base extends TypedAtomicActor {
private int _hopcount = 0;
if(_hopcount <= 3) {
some code;
}
public function() {
_hopCount += 1;
}
}
I've Parent and child(extends Parent) class To initialize the constructors, I'm injecting from google.juice#injector. Let me show the code,
Parent.class
public class Parent{
private Animal animal;
@inject
Parent(Animal animal){
this.animal = animal;
[code].....
When I do this, ClassCastException is happening. Why is it so? Is there any way to convert instance of parent to child instance.
Given the case I have an object which is assigned only once. What is the difference in doing:
public class MyClass {
private MyObj obj = new MyObj("Hello world");
private MyClass(){}
//...
}
and
public class MyClass {
private MyObj obj;
private MyClass(){
obj = new MyObj("Hello world");
}
//...
}
Is there a difference in performance or usability? (Given also the case there are no static calls expected) ....
The term "Local variable" is related to scope. That is a local variable is one which is defined in a certain block of code, and its scope is confined inside that block of code.And a "Member variable" is simple an instance variable.
I read in a discussion forum that when local variables are declared (example code below), their name reservation takes place in memory but they are not automatically initialized to anything. On the other hand, when member variables are declared, they are automatically initialized to null by default.
Java Code: public void myFunction () {
int [] myInt; // A local, member variable (because "static" keyword is not there) declared
} mh_sh_highlight_all('java');
So it seems that they are comparing local variables and member variables. While I think a member variable can also be be local in a block of code, isn't it?
Given a reference variable : Car c1 = new Car();
when we create another variable and set it equal to the first : Car c2 = c1;
we're pointing c2 at the same car object that c1 points to (as opposed to pointing c2 at c1, which in turn points at the car). So if we have code like,
Car c1 = new Car();
Car[] cA = {c1, c1, c1, c1};
are we doing the same? Are we creating four *new* reference variables, each of which points at the same car (again as opposed to pointing them at c1 itself)? I think so, but want to make sure I'm understanding this correctly.
I have a JFrame jf and JPanel jp on it. jp has five TextFields named cel1, cel2.. cel5. I wish to construct a String Cel + for loop index and run a for loop to reset the values of all the text fields using a single statement such as cel1.SetText("abc"). Similar things can be done in foxfro. How does one do it in java?
View Replies View Relatedin a set of instructions they keep referring to instance versions of things I've heard of before ie "private instance array of String references" (wtf is a string reference?) or "instance string variable" so what does all this mean?
View Replies View Related.I was reading head first java book and saw a barbell question on page no. 280,question-"what if you want to write a class in such a way that only one instance of it can be created,and anyone who wants to use an instance of the class will always use that one,single instance?"
View Replies View RelatedIn the following example, I compute new_amount_d in 2 different ways and I get 2 different values although it should be the same in theory.
Is there a way to get the same value with BigDecimal for instance?
public class num004
{
public static void main(String[] args) {
double amount_d = 1000;
double interest_rate_d = 0.03;
[Code] ....
I have a method that accepts JSONArray as parameter and returns the values of it as ArrayList Object. My question which of these ways is appropriate in populating the ArrayList object this method populates the arraylist upon creation of object (I don't know what the right term to use, but as netbeans IDE suggest, JSONArray object should be final since it was used in inner class.).
private List<String> getStringList(final JSONArray jsonArr) {
return new ArrayList<String>() {
{
try {
for (int i = 0; i < jsonArr.length(); i++) {
add(jsonArr.getString(i));
}
} catch (JSONException ex) {
ex.printStackTrace();
}
}
};
}
this second method is the usual way of populating collection
private List<String> getStringList(JSONArray jsonArr) {
List<String> strList = new ArrayList<String>();
try {
for (int i = 0; i < jsonArr.length(); i++) {
strList.add(jsonArr.getString(i));
}
} catch (JSONException ex) {
ex.printStackTrace();
}
}
What are the advantages and disadvantages between the two? like which is faster? or which consumed larger memory?
I have been working on a program that is meant to use a class' instructions in a program to add a value to a variable, save it, and present it. This is my class
public class Car
{
//FIELDS
private int yearModel;
private String make;
private int speed;
//METHODS
public Car(int carYearModel, String carMake)
[Code] .....
Whenever I call the accelerate method, a value of 5 is to be added to the speed variable. But whenever I call accelerate, it doesn't increase! I just don't understand why not. I've tried different renditions of adding 5 to speed and it doesn't quite work. I don't get any errors when I compile, just runtime, when it doesn't add 5 to speed.
So far in my assignment I have successfully opened a text file. However I am required to do more:
1) As each line of text (containing names and ages) is read a new Runner object is created with its instance variables set thus: ! (Runner class already created )!
- name : set directly set from the value in the file
- agaGroup : can be worked out from the given ages:
< 18 should be 'junior'
> 55 should be 'senior'
the rest should be 'standard'
2) the instance of Runner should be added to the list referenced by the instance variable runners.
I have used if statements to create the junior list, however I do not see the full list of names and ages in the variable runners as I am requested to.
I am sure there is a for loop involved somewhere but I do not know how to:
a) use the for loop in my method
add a new Runner object with the variable mentioned.
I include the code I have done so far as a file - p.s I use Bluej.
public class MarathonAdmin
{
// instance variables
private String runners;
private String age;
[Code] ....
Can I declare a class as
public static final?
Because I can declare a variable as public static final pi=3.14;
I want to create a new instance of a Java model class for each new request coming to a servlet.
How to do that without doing that in doGet() or doPost().
I have the following 2 classes:
class Address {
private int a;
public void set_a(int a) {
this.a = a;
}
}
class Person {
private Address address;
}
How do i access the method set_a() (through the "address" in Person) from another class which contains main() ?
I have 1 textfield and 1 button on a JFrame and having 10 such frames stored in ArrayList al and getting the JFrame instance from traversing the ArrayList at execution time ,So is there a way to access textfield using JFrame instance or i have to name the textfield diffrently 10 times for each frame .
View Replies View RelatedI am working with a JFormattedTextField. After adding the text of the FormattedTextField to an LinkedList i want to read it out and sum it up. So I have a problem to convert the String to and integer...
Example:
23.00 - to 23.00
+ 11.00 - to 11.00
--> 34.00
I have tried it with splitting the string but it didn't work. How to do it?