I just want to be able to read type and weight in the Letter class I created (I created read out messages to check in the Letter class). I am able to read it with in the Mail class.
package org.mailprice.postage;
import java.util.Scanner;
public class Mail {
static Letter letter;
[code]....
Does child class gets a copy of the methods and variables of parent class?
public class test1 {
public static void main(String a[]) {
Child c = new Child();
c.print();
[Code] ....
why is the output 1?
I will like to add to the questions about constructors and its this. I have a class A with a constructor, i have a class B which initialize the constructor. also i have a class C which needs a variable in class A but doesn't need to initialize the constructor of A. the question how do i access the variable of class A without initializing the constructor.
View Replies View RelatedI wanna know which is the best way to access a variables within a class ...
Using direct access or using the variable accessor ...
Example :
public class Numbers{
private int n1;
private int n2;
public void setN1(int n){
n1 = n;
[Code] ....
This program should create a GUI that has 5 classes together on a grid layout. The problem that I am having is that the user input class has the input for kwh, hours, and gallons. I am having problems getting that information from the user input class to the totals class.
user input class:
package applianceutilitycalculator;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner;
import javax.swing.*;
[code].....
The totals class should take the info from the kwh hours and gallons and do the math to get a total and display it in a JTextField(?).
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?
View Replies View RelatedI write a small program. I want post my integer variables in the next class. Here a code(I wanna change answer color):
Main class(pagrindine.java):
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.event.*;
//Mokinio rinkinukas su skaiciofke kur gali keisti atsakymo spalva, pabandyti sukurti uzrasu knygute.
[code]....
So, I want to post variables r,g,b from class slideris.java in the pagrindiness.java.
if I declare
class Example
{
int x=10;
......
}
It is not showing any error but when I declare
class Example
{
int x;
x=10;
............
}
it showing compile time error ....
I have An Issue With My Java Applet. Im Trying To Share My Variables With Another Class, But Its Not Working.
Class 1
package com.Tobysmith10.game.main;
import java.applet.Applet;
import java.awt.Graphics;
public class Game extends Applet{
public void init(){
setSize(850,480);
public void paint(Graphics g){
g.fillOval(x,y,20,20);
}
}
Class 2
package com.Tobysmith10.game.main;
import java.applet.Applet;
public class gameLoop extends Applet implements Runnable{
public int x, y;
public void run(){
while(true){
x = 100;
y = 100;
}
}
}
So im sharing the x and y variables with the Class 1 , but I get yellow lines under it and when i run the program, it crashes, how do I get class 1 to recognize the variables from class 2 ?
I am having some problem accessing variables from an array instance of a class. Heres what i have done;
In the main class:
Example obj[]= new Example[4];
In the main class constructor:
obj[0] = new Example(0);
obj[1] = new Example(1);
obj[2] = new Example(2);
obj[3] = new Example(3);
In the main update() method:
if(condition)
//update
In the Example class constructor:
private boolean change = false;
In the Example class update() method:
if(x >20)
change= true;
Now, i want to access the variable change from the main class, how do i do it? The 'condition' in the if statement is the condition of wether the change variable ia true or false. How do i access it?
I have to create an application that deals with maps.
I first have to create the instance variables for the class.
So very simply if my hashmap is going to consist of football clubs and players. Football clubs being a string value for the key and players being a set of strings for the values. How would I go about creating the instance variable in a class for this?
I can't seem to find anything that specifically deals with instance variables and constructors for maps.
how to get access from variables in a super class or a subclass. Here is what I got:
1) I have a super class that is in Jar file, I created a link in Eclipse, I know that the link is created correctly, I am going to concentrate just in one variable, so I don’t have to put all the code here firstName; in the super class(the one that is define in the path)
public class CommissionEmployee {
// Field descriptor #6 Ljava/lang/String;
private java.lang.String firstName;
in my class i have 6 argument constructor
From the tutorial:instance variables can be declared in class level before or after use.But the code below does not compile. Why?
Java Code:
public class MainApp {
i=5;
public static void main(String[] args) {
System.out.println("Hello World");
}
int i;
} mh_sh_highlight_all('java');
I am having trouble taking user input and passing it to another class as a variable. If I assign the value explicitly (see line 59), it works just fine. What I want to do though, is assign the input from inputField to the variable inputVariable. I tried using:
inputVariable = inputField.getText();
This does not work. Regardless of what is typed into inputField, the output I get is just:
"The user typed "
package example;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
[Code] .....
I have a school assignment that involves me sorting an array of objects based on one of the class String variables. I am using as the title says a simple selection sort method. The problem I'm having is that when I run the program in debug mode, it never seems to enter the if statement in the inner loop. I would like to say I've tried a number of things to figure it out, but honestly I'm just stumped as to why it's not working.
Here is the code:
public static void sortTransactions(Transaction[] oTransaction){// This is the sorting method, obviously it's not done so it currently just prints to screen.
System.out.println("Successful call to sortTransaction()");
String min = "";
int curInd = 0;
Transaction[] temp = new Transaction[1];
[Code] ....
The output when I check to see if the array is sorted verifies that the array never does get sorted.
I am very Java illiterate and I need to know how would i set all the variables in the first class to null or 0 to make a new method to clear everything.
import java.util.Arrays;
import java.util.Scanner;
public class studentMethods
{
private double totalScore;
private int count;
[Code] ....
Creating a class. Specification are given as:
Create a class called Employee that includes three pieces of information as instance variables:
-Employee ID (string type)
-first name (string type) (default value 'John')
-last name (string type) (default value 'Smith') and
-monthly salary (type double).
-No argument constructor that initializes the three instance variables. The employee id should be generated using the following process:
The employee id should be a combination of first initial, last initial and a number starting from 10001 for the first employee and increasing by one for each employee. e.g. if John Smith is the first employee then its id will be JS10001 and if George Brown is the second employee then its id will be GB10002
-Provide get and set methods for each instance variable. The set method for monthly salary should ensure that its value remains positive - if an attempt is made to assign a negative value, leave the original value.
How do you declare methods for a class within the class whilst objects of the class are declared else where?
Say for instance, I have a main class Wall, and another class called Clock, and because they are both GUI based, I want to put a Clock on the Wall, so I have declared an instance object of Clock in the Wall class (Wall extends JFrame, and Clock extends JPanel).
I now want to have methods such as setClock, resetClock in the Clock class, but im having trouble in being able to refer to the Clock object thats been declared in the Wall class.
Is this possible? Or am I trying to do something thats not possible? Or maybe I've missed something really obvious?
As web server has multiple threads to serve client requests in Thread Pool & to ensure Thread Safety we should not use any variables or Objects at Instance/Class level.But in case of Session Variable which one is the Best Practice as the Session object is used by all the requests to have the same Session ID.
My Code :
public class MyServlet extends HttpServlet {
private static Logger log = Logger.getLogger(ClientRegistrationServlet.class);
private HttpSession session; /* This is used at Instance Level*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
[code]....
I am currently building a Plugin system for an application and I wanted to add a little security feature.
I have read many tutorials on this and they basically all came down to the same answer:
"Its complicated: You need a custom class loader and security manager and ... and even then its still tricky"
So I thought, before I load the classes dynamically I will simply read the class files. Why bother with a SecurityManager or ClassLoader if I can simply whitelist all allowed classes and search for all illegal Class access before I even load anything.
I have an XML document that have multiple levels of nesting:
<virtue name="Innocence">
<rank ranklvl="1">
<stat type="Physical Mitigation" value="84" />
<stat type="Resistance Rating" value="89" />
<stat type="Tactical Mitigation" value="29" />
</rank>
<rank ranklvl="2">
[Code] ....
I need to return all the different values within each child element... i.e.
Virtue: Innocence
Rank: 1
Physical Mitigation = 84
Physical Rating = 89
Tactical Mitigation = 29
Virtue: Innocence
Rank: 2
Physical Mitigation = 162
Physical Rating = 175
Tactical Mitigation = 54
I can read the XML okay but I get an error on displaying the information.
for (int temp = 0; temp < nList.getLength(); temp++) {
//Node nNode = nList.item(temp);
Node nNode = nList.item(temp);
//System.out.println("
Current Virtue :" + nNode.getNodeName());
[Code] ....
So here is my code:
while (key != 3) {
if (key == 2) {
System.out.println("Input from a file");
// System.out.print("Enter file name: ");
// String str = expression.nextLine();
int i = 0;
File file = new File(
[code]....
What I need to happen is the file gets read in, the file is in the form:
a * ( b + c ) / 2 + ( 8 * b )
a = 5
b = 10
c = 20
( x + y ) * z
x = 13
y = 21
z = 3
And so on. My code is supposed to start at the beginning and have output like:
Infix: a * b ( b + c ) / 2 + ( 8 * b )
variable values:
a = 5
b = 10
c = 20
**It then needs to store the variable names along with their values in a hash table**
postfix: a b c + * 2 / 8 b * +
value: 155
And it continues reading the file in the same fashion.
My issue is I am not properly extracting the variables and their values from the file. I have the variables in an array list actually, so I have those, but don't know how to efficiently navigate to the values, then store the character and value in a hash table, while protecting against possible blank lines within the file. Thus just calling nextLine()s and next()s wouldn't work to get to values because they would lead to an error.
Why I can create an Instance of a class that contains non static variables within the static main method ?
This program runs fine
import java.util.*;
public class Test{
public int j;
public static void main(String[] args) {
Test test1=new Test();
System.out.println(test1.j);
[Code] .....
Class UserAssessBean{
private String username;
private int userid;
private ArrayList<ModuleBean> module;
--{get/set}--
[Code] ....
How can i access the getters/setters of module bean, when it was returned as array list in UserAssessBean?
Regarding the lifecycle of servlet , in headfirst servlet i can find :
You normally will NOT override the service() method, so the one from HttpServlet will run. The service() method figures out which HTTP method (GET, POST, etc.) is in the request, and invokes the matching doGet() or doPost() method. The doGet() and doPost() inside HttpServlet don’t do anything, so you have to override one or both. This thread dies (or is put back in a Container-managed pool) when service() completes.
How can I call the doGet method of the subclass from the superclass. i am not getting this .
I have a quick polymorphism question. I have a parent class and a sub class that extends the parent class. I then declare an array of parent class but instantiate an index to the sub class using polymorphism. Do I have to have all the same methods in the child class that I do in the parent class? Here is an example of what I mean.
public class ParentClass
{
public ParentClass(....){ }
public String doSomething(){ }
}
public class ChildClass extends ParentClass
{
public ChildClass(....)
[Code] ....
Is polymorphism similar to interfaces where the child class needs all the same methods?