New to java/programming and i cant understand why the pen variable does not display the the correct value ... For example for input 1 ; 2 ; 3 ; 4 both variables will display 10 and i dont understand why pen does not have the value 6 .
import acm.program.*;
public class Chap4_ex12 extends ConsoleProgram {
public void run () {
int pen = 0;
int r = 1;
int sum = 0;
while (r !=SANTINEL) {
r = readInt(" ? ");
pen=sum ;
[code].....
If I have an integer variable like int a=9 then in the switch case If i write
switch(a) {
case 4+a: System.out.println("hii");
}
Then why is this statement a compile-time error that variables cannot be used inside a case statement why does the compiler not subtitutes the values in place of the variables.
So basically what problem it creates for which the language developers did not include it as a proper syntax,is there any reason behimd this because of jump table?
i'm trying to construct a deadlock deliberately by coding this scenario:
1) Thread A enters a synchronized method of object foo
2) Thread A goes to sleep (thus still holding the key of foo)
3) Thread B enters a synchronized method of object bar
4) Thread B tries to enter a synchronized method of foo (, but cant)
5) Thread A wakes up and tries to enter a synchronized method of bar => deadlock
I'm trying to keep the code really minimalistic, i.e. just 2 threads and 2 objects.
I also dont want to use this syntax:
synchronized(a){
...
}
but would like to achieve this just by calling synchronized methods of 2 different objects (as stated above).
//construct and populate the Time menu
Menu mnuTime = new Menu("Time", true);
mnuBar.add(mnuTime);
MenuItem mnuCurrentTime = new MenuItem("CurrentTime");
mnuTime.add(mnuCurrentTime);
[Code] ....
E:Calculator.java:64: error: cannot find symbol
if (arg == "Time")
^
symbol: variable arg
location: class Calculator
1 error
Tool completed with exit code 1
In other words in a table view with several editable columns, when a new row is added this row does not contain any column cells yet. Cells are added on demand once a column gains focus and starts editing. Is this the case? Is there any way to force the row to construct all cells eagerly?
View Replies View RelatedI am working on writing a desktop based email client using swing. First some specifics: I need to show emails in a (dynamically updatable) vertical list. Each item in this vertical list would represent an email showing: (a) the subject, (b) a photo of the sender that I have locally available & a couple of buttons. So, I plan to create a JPanel containing a JLabel to show the Subject, The photo inside a JLabel & JButtons. I have the layout of this panel done and is not a problem.
My problem is with stacking all these JPanels (each representing an email) and showing them on the UI as a list. I am not sure of any way to do this. Moreover, when a new email is received, it has to be displayed at the top of the list (not at the bottom).
Specifically, I need a good way of displaying a vertical list of JPanels & be able to add new JPanels at the top of the list.
I am trying to write a program that read from a csv file called matches.csv ... A single football match can end with a win or a draw: in first case the winner team get 3 points and the loser none, in the second case of draw each of the two teams get 1 point.
In the file it contains the following data.
17/08/2013 Arsenal Aston Villa 1 3
24/08/2013 Aston Villa Liverpool 0 1
This means that a match has been played on the 17/08/2013 where Arsenal scored 1 goal while Aston Villa 3 goals: thus Arsenal got 0 points while Aston Villa 3 points.
How can I structure my output to make it make it read
Position Team Played Points
1 Aston Villa 2 3
2 Liverpool 1 3
3 Arsenal 1 0
My code so far:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Teams {
public static void main(String[] args) {
String fileName = "matches.csv";
[Code] ....
package SystemandDesign.BinaryTree;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.List;
import java.io.ObjectInputStream;
[Code] ....
So I am having trouble with trying to get the main method to work. The program is supposed to construct a BinaryTree, and deserialize a file that is used for the Tree.
Let's get it out of the way -- I'm stumped. On something that should be pretty simple to solve. Code follows.
public class Sum {
public static void main(String [] args) {
Double nSum = 0.0;
Double aDouble = 100.0;
for (int i = 0; i < 1000; i++){
nSum += 0.1;
[Code] ....
The output:
100.000000
100.000000
false
false
false
false
false
Process finished with exit code 0
I wrote another simple program and hardcoded the values: aDouble = 100.0; bDouble= 100.0000
Using aDouble.equals(bDouble) returns true, just as one would expect.
So what am I overlooking?
Having two values
<c:set var="var1" scope="view" value="#{ID1}"/>
<c:set var="var2" scope="view" value="${ID2}" />
I tried in <c:if test=${var1 == var2}>
and eq also
above condition is not working. Both are same object. How to check?
Variables defined in interface are public static and final so I was thinking that we should not be able to override the variables in a class thats implementing the interface. But when I am compiling the below class, it compiles fine and gives the correct values. but when I did disp.abhi = 35; it gives a compile error (cannot override final variable)
interface display{
int abhi = 10;
void displayName();
[code]....
This is my first time working with C++ and I have put together this program and came up with two errors and I am unsure what it is wanting me to do. The errors I got are:
1>c:usersownerdocumentsvisual studio 2010projectsweek5week5passing_by_value.cpp(30): error C2064: term does not evaluate to a function taking 1 arguments
1>c:usersownerdocumentsvisual studio 2010projectsweek5week5passing_by_value.cpp(38): error C2064: term does not evaluate to a function taking 1 arguments
#include<iostream>
using std::cin;
using std::cout;
using std::endl;
//initialize arrays
int incr10(int* numa,int* numb);
[Code] ....
I am new in this programming language, java. I have a problem after I set my path ";C:Program Files (x86)Javajdk1.7.0_51in". I made a simple program but an error occurred. Here's the screenshot.....
Attached image(s)
I continuously get an error for lines 34, 36, and 37 saying that the variables may not have been initialized.
import java.util.Scanner;
import java.util.Random;
public class MathTutor {
public static void main(String[] args) {
Random r = new Random ();
Scanner input = new Scanner (System.in);
/*int min=1;
int max=10;*/
int num1,num2,operation;
int n1= r.nextInt((9+1)+1);
int n2= r.nextInt((9+1)+1);
operation= r.nextInt(3);
int correctAnswer;
int userAnswer;
[code]....
Class 1:
view sourceprint?
1 public class one {
2 public static void main(String[] args){
3 int num = 0;
4 System.out.println(num);
5 two.change(num);
[Code] .....
This should print 0, then 1, but it prints 0, then 0. How do I make it print 0 then 1 with the same format?
Let's say within a class I create a method that takes care of creating a java swing layout with labels, buttons etc.. then attach an action listener (inner class) for each button to change a respective label text. All I would need is that the action listener method can access and modify the label as needed.
Have read about static, protected, private, getters and setters but honestly bit confused about which structure should be adopted as a best practice. Global static protected variables for the labels along with private inner classes implementing ActionListeners believe will do the trick and will be able to access the labels but not convinced this is good practice.
you can also refer this link Local variables in java?Local variables in java?To meet temporary requirements of the programmers some times..we have to create variables inside method or bock or constructor such type of variables are called as Local Variables.
----> Local variables also known as stack variables or automatic variables or temporary variables
----> Local variables will be stored inside Stack.
-----> The local variables will be created while executing the block
in which we declared it and destroyed once the block completed. Hence the scope of local variables is exactly same as the block in which we declared it.
package com.javatask.in;
class A{
public static void main(String args[]){
int i=0; // Local variable
[code]....
Is there any way to save variables while I'm using applet as single runnable .jar file?
For example if I start app first time some variable has value of 100. While using app it changes to 200. After closing app it disapear and next run gives me 100 again instead of 200. Is there any way to save that 200?
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 RelatedDoes a variable have public access modifier? if we can use it within the class and outside of the class then can i access a public variable as follows??
class mo
{
void display() {
public int a=9;
System.out.println(a);
}
public static void main(String[] args) {
mo m=new mo();
m.display();
}
}
ERROR:
It shows 6 errors :-O.
Error 1. illegal start of the expression
2. class,interface, or enum expected
I'm having some trouble figuring out how to change the value of a variable that is passed into a class. I've tried just changing the variable, I've tried changing it by using the this.variable command, and I've even tried calling the setter class from within the class to change it, but it's still not working right. The first class is the one with Main in it and I just feed it some dummy data:
public class ExamConverter {
public static void main(String[] args) {
// TODO Auto-generated method stub
Age testAge = new Age();
[Code] .....
This is the other class to calculate the age the way we do it on psych tests - it might not be mathematically accurate, but it's what all the tables and such for raw to scaled score conversion are based on, so the math needs to be the same as opposed to "accurate" because of some months having 30 or 31 days, etc.
public class Age {
//==================Properties==================
// Variables for the test date and client date of birth
private int TestMonth;
private int TestDay;
private int TestYear;
private int ClientMonth;
private int ClientDay;
private int ClientYear;
[Code] ......
Based on this dummy data, the output is:
Test: 5/4/2014
DOB: 5/5/1971
Age Years: 43 Months: 0 Days: 0
However, it should be:
Test: 5/4/2014
DOB: 5/5/1971
Age Years: 42 Months: 11 Days: 29
Is it possible to have the value of an entered String to be set as the name of the String to be created whilst running.For example: String username= Keyboard.readString() & the user entered for example the word: "Hello".Is there a way how I can make the Java Program create another String named Hello (Inputted value of String username).
If this is allowed, what do I have to use and if possible show me exactly what I have to do with the example mentioned above?
I've looped a method 14 times, each time it focuses on a different person and how many oranges he/she has eaten. I now want to calculate the total amount of oranges eaten and exactly how many oranges are eaten on average, how can I do that?? the amount of oranges eaten is variable, they are determined by what number the user types in.
View Replies View RelatedThe problem is to figure out the number of cartons needed to box up the strawberries picked by the farmer and his wife. The farmer picks 8.4 lbs per hour and the wife pick 10.8 pounds per hour. They pick from 8 am until 4Pm (8 hours). You can put 20 pounds per box.I understand the word problem and how to declare and initialize variables. I'm just confused how to display the math into java to solve it.
View Replies View RelatedSo I just want to store a Key in a HashMap which can related to two values. For example, the Key "ABC" related to "Fire" which in turn relates to "Heat".
How can I code this in a HashMap?
In most of the GUI examples, it declares the variables right at the start as private.
public class KiloConverterWindow extends JFrame
{
private JPanel panel;
private JLabel messageLabel;
private JTextField kiloTextField;
private JButton calcButton;
private final int WINDOW_WIDTH = 310;
private final int WINDOW_HEIGHT = 100;
In one example though, it declares and creates the different objects in the constructor.
public BorderWindow()
{
setTitle("Border Layout");
setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
JButton button1 = new JButton("North Button");
JButton button2 = new JButton("South Button");
JButton button3 = new JButton("East Button");
JButton button4 = new JButton("West Button");
JButton button5 = new JButton("Center Button");
Now what I assume, is that for the second example snippet, because it's sole purpose is to show you the Border layout, there are no events tied to any buttons, and there is no data, other than the names of the buttons. With the first snippet, it's purpose was to show the kilometer to miles converter using a GUI. The purpose of making it private is to prevent the data from being altered from outside code. If I have the right idea, I feel like they should have continued to keep their examples consistent.