Simple Averaging Program Using Two Different Classes?

Apr 9, 2014

This is a simple project that i was using to test my current java knowledge (kinda like revision) and for that i used two classes to make a simple averaging program. i know i0m making it more difficult but like i said i'm testing myself but i come up with an unexpected error. Here's the code:

- 1st Class

import java.util.Scanner;
public class Main {
public static int num;
public static int total = 0;
public static int average;

[Code].....

Now the problem is after inputing the numbers it doesn't give me the average but the value of 0.

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Averaging Grades Program Throwing Exception With Negative Numbers

Nov 17, 2014

So I have re-written the code but it is still not running correctly. Any number i type in it throws an exception, also i need the program to add the totals that i type in and then once i type -1 into the prompt button list all the number i typed in and give me the average.

import java.awt.*;
import java.awt.event.*;
import javax.swing .*;
import javax.swing.text.*;
public class Averages extends JFrame
{
//construct components
JLabel sortPrompt = new JLabel("Sort By:");

[Code] .....

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Sep 30, 2014

I do now have the problem where i have to insert the numbers 1 to 100 individually in order to allow the program to accept a grade as high as 100%.

Also as soon as i type in a negative number the system crashes and shows me a error as attached.

/*
Averaging grades
To use the Java Swing interface to calculate the average of up to 50 grades.Average is calculated once -1 is entered as a value. The grades are then sorted from lowest to highest and displayed in a content pane which also displays the average.
*/

import java.awt.*;
import java.awt.event.*;
import javax.swing .*;
import javax.swing.text.*;
public class Averages extends JFrame {
//construct components
JLabel sortPrompt = new JLabel("Sort By:");

[Code] ....

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Feb 2, 2015

Ok so I have my program working for the most part. In this program I am supposed to take input from the user until they enter a negative number and that works, the problem is that it doesn't work if I enter a negative number on the first prompt. For example if I enter a 100 it would prompt me again and if I enter a negative number it would quit and give me the average, but if I enter a negative number the first time I am prompted the program just gives me an error. How do I fix that?

import java.util.List;
import java.util.ArrayList;
import java.util.Scanner;
public class Application {
public static void main(String [] args){
Scanner input = new Scanner(System.in);
List<Integer> grades;

[Code] ....

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Aug 18, 2014

Write a Swing program that declares an empty array of grades with a maximum length of 50. Implement a JOptionPane input box within a while loop to allow the user to enter grades. When the user enters the sentinel value of -1, that will signal the end of the data input loop.

After the grades are entered, a content pane should display the grades sorted from lowest to highest. Write a loop that goes through the array looking for elements that are greater than zero (0). Keep a running count of those items, and also accumulate them into a grand total. Divide the grand total by the number of grades entered to find an average, and display the average at the end of the sorted list of grades. Use the DecimalFormat method to display the average to 2 decimal places.

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Java Code:

Class Hops{
String Name;
float Alpha Acid;
float Beta Acid;
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Class Malt{
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float extract;
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CList RecipieList; mh_sh_highlight_all('java');

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I'm getting back into the swing of things with Java after using I'm asked to utilize a simple GUI in order to take in the starting data, I cannot seem to get this to work. I'm getting this error Exception in thread "main" java.lang.NullPointerException

at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at Input.buildPanel(Input.java:53)
at Input.<init>(Input.java:27)
at InputDemo.main(InputDemo.java:5)

I've created two classes

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private JLabel messageLabel;
private JLabel messageLabel1;
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[code]....

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import javax.swing.*;
import java.awt.*;
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package asgn2;
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import acm.program.*;
public class pyramid extends GraphicsProgram {
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[code]...

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Mar 26, 2015

I'm trying to read lines from a textfile and count all the words using String Tokenizer. However I keep getting an error "Unhandled exception type FileNotFoundException" on my IDE(Eclipse) referring to lines 13 and 8. When I let the IDE automatically, and I've even tried typing this manually, insert a try-catch block more errors show up concerning inputFile. When I insert the throws FileNotFoundException for each method it compiles but after running it gives me a FileNotFoundException for textfile.txt. What's even more interesting is that when I copy the .java file out of the IDE project folder, place it in a random empty folder on the Desktop with the textfile.txt, and try running it through command line, it gives a NoSuchElementException: No line found.

import java.util.Scanner;
import java.util.StringTokenizer;
import java.io.*;

[Code].....

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Nov 1, 2014

I have to write an encryption/decryption program for a sentence entered by the user that uses arrays. Here is my code so far. I'm kind of lost on what to do next in the code.

import java.util.Scanner;

/*Program that encrypts then decrypts a sentence
Encryption
*/
public class Encryption extends java.swing.JFrame{

[code]....

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Mar 11, 2015

i am working on my assignment in Compro 2, we are ask to make a simple calculator program

here's my code;

import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JFrame;
import java.awt.BorderLayout;

[code]...

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Nov 19, 2014

My code below is trying to make a connect four program without GUI. I'm having trouble with getting the players to make their moves. What should I put in my "makeAMove" method...

Java Code:

public class Connect

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final static int MAXCOL = 7;
public static void main(String[] args){

[code]....

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Jan 22, 2014

I am having a difficult time writing what started out as a simple vending machine program. As I go on though, it seems that I'm overcomplicating it and it is getting messy, so I have resorted to the forum before I really get off the path. how to clean it up? I'm going to list a few of the problems I am having with the code below:

1. The user is supposed to enter his/her money and the program is to read each value separately (Do-While loop) and keep a running total of the money entered. I can't seem to get the right code format to do this. I was trying to do this with the variable total and so that is why the total exists in the switch statement, but it did not work.

2. In the second Do-While statement, is there a way to kick back an error when their are insufficient funds to purchase an item? Instead of getting a negative change return.

package practice;
import java.util.Scanner;
public class Practice {
public static void main(String[] args) {
double count, total;
int item;
//Display Available Options To Customer
Scanner input = new Scanner(System.in);
System.out.println("*VENDING MACHINE*");

[code]....

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Sep 13, 2014

I'm very new to Java (I literally started learning it yesterday) and I've been working on a simple program that's meant to simulate interactions between optics objects and light rays.

Everything has been going really well, except that my mirrors only reflect the first ray that comes in contact with them.

Here's a screenshot : 2014-09-13 at 7.39.23 PM.jpg

I wrote 7 classes:

Main class to create the optics objectOptics class. the most important class that uses a recursive function to detect the nearest intersection point of a ray with the nearest optics object. It then calculates a reflected ray and inputs it back into the function until no intersections are found or the max recursion depth is met.Ray. creates a rays (in parametric form O + tD where O is the origin, D is the direction and t is a non-negative scalar)Object. empty abstract class used for polymorphism (so when i add more optics objects like prisms and lenses they'll share the object type)Mirror. Basically a line segment created with the Line classLine. Creates a line segmentDraw. JComponent with paintComponent function that loops through an array of shapes and draws them to the screen.

What I know so far is that the problem boils down to the checkRay() function in the Optics class. When a mirror has already reflected a ray, the line:

Intersection sec = new Intersection(ray,(Mirror)obj);

creates an intersection with a null point.

I debugged it line by line and found the problem was that my variable 't' (that is the parameter for the parametric line which represents the mirror) in the Intersection class got big values when it's meant to be between 0 and 1 (since it's a line segment), which resulted in the function returning null (as it should when 't' is not between 0 and 1).

I've confirmed with tests that this has nothing to do with the specific mirror or angle of incidence. It only occurs when a mirror has already been intersected with by a ray.

I've found out that my function:

public PVector getNormal(PVector D){
D.normalize();
return new PVector(D.y,-D.x);
}

Changes the value of the 'D' PVector of the mirror inside my 'objects' ArrayList. How can it access the private PVector 'D' from outside the Mirror class? This normalization to the direction vector is what causes the Intersection class to return null the second time around!

The problem was that in the getNormal function, the input vector argument was a reference to the 'D' vector for the mirror in my 'objects' ArrayList so the .normalize() function acted upon the original vector, changing it's value and screwing things up. The two classes I talked about:

Optics: (note line 64. this line returns a null intersection when it shouldn't)

package ofer.davidson;
 import java.util.ArrayList;
 public class Optics {
 //Arrays to store all the optics objects and rays that are created
ArrayList<Object> objects;
ArrayList<Ray> rays;
 
[Code] .....

Also why doesn't my background turn white??

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May 12, 2015

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For some reason, the program is always returning -1, rather than the index of the string within the ArrayList when there is one which matches the search criteria.

Here is the code:

public int getIndex(ArrayList<String> text, String target)
{
int i = 0;
int index = -1;
boolean found = false;

[Code].....

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Apr 26, 2015

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Apr 29, 2015

I am working my way through "Head First Java" and typing the code in the book into Notepad++ as I go. In the first few chapters the code was simple and only had one class (main). Now the code has two or more classes. Originally I would compile the code in the Command Window by typing "javac" and the program's name. After it compiled I would execute the program by typing "java -classpath . " and the program's name. However, now when program has several classes I get the following error: Could not find or load main class. Below is a program I am having issues with... does it need to be saved as two separate files?

class DogTestDrive {
public static void main (String [] args) {
Dog one = new Dog();
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[Code] ....

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Aug 12, 2014

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With compound interest, the interest is applied to all money earned. So, starting with $1000 at 10% annual interest, after one year the user would have $1100 (the original amount plus $100 interest) and after two years the user would have $1210 (the $1100 they started with at the beginning of the year plus the $110 interest).

The requirements of this program are:

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Sample output ($10000 initial investment, 10% simple interest, annual, for 4 years):

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1 10000.00 1000.00 11000.00
2 11000.00 1000.00 12000.00
3 12000.00 1000.00 13000.00
4 13000.00 1000.00 14000.00

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at home.Main.main(Main.java:14)"

Here is the code! :

Main.java class
Java Code: import java.util.Scanner;
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[code]....

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Feb 8, 2015

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Obviously, that [ bracket is not an 'A'. I realise the issue falls with the equation, Here is my code:

public class SimpleEncryption {

/**
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*/
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[code]....

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Aug 15, 2014

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A. Set the day.

B. Print the day.

C. Return the day.

D. Return the next day.

E. Return the previous day.

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G. Add the appropriate constructors.

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[code]....

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Second, how can the main method not refer explicitly to other classes? It has to create some objects after all...

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Ex.
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To: PersonB
Email message is here

I have gotten this far, but every time I append my "email.print()" into the next class, it never can print any of the Strings.

Main Args Class:

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[Code] ....

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Java Code: package ehu.student;
public class ConversorTemperaturas {
/*--------------------------------------------------------------*/
/*Clase que dado una temperatura en Fahrenheit la canvierte en C*/
/*--------------------------------------------------------------*/
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[code]...

When I write t.farenheit2celsius(25.6), appears the following error: "The method farenheit2celsisus(float) in the type ConversorTemperaturas is not applicable for the arguments (double)"If i change in the class the type float for double there is not problem. Why can't i use the type float?

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