Returning Values With Methods?

Sep 24, 2014

The code is below. The program runs a series of calculations based on data input by the user. My problem is that for the most important thing I'm looking for, total kg CO2 emissions, I continually get an answer of 0.0. What I need is a sum of the individual total emissions as calculated in each method, i.e. the values which are printed with the following: System.out.println(trans); System.out.println(elec); and System.out.println(food);

The total should be something like 25040 or whatever, depending on the value of the inputs provided by the user, but I'm constantly getting a total of 0.0., which is obviously false. Could have something to do with the way I've initialized my variables, or something to do with the limitations of returning values from methods.

import java.util.Scanner;
 public class CarbonCalc {
 public static void main(String[] args) {
double trans = 0;
double elec = 0;
double food = 0; 
giveIntro();
 determineTransportationEmission(null);

[code]....

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Returning Values Between Two Classes With Methods

Feb 4, 2015

I have a very standard Lab assignment. It's probably been seen a lot. I wrote the first part not realizing I had to write a second class to do use the methods. I'm not sure how to change my program to call methods from my second class instead of doing all my calculations with user input in my first class.

Here's the first class' code:

package tickets;
//Imports classes used for "Ticket" application.
import java.util.*;
import java.text.DecimalFormat;
public class Tickets {
 
[Code] ......

The code is obviously incomplete. I have not tried to compile, nor would I expect it to compile right. I'm not sure how to move my calculations from the first class shown above into my second class and use them as methods.

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Jan 23, 2015

I'm writing a program that involves the use of set/get methods. I will submit a sample code of my issue. The format appears to be alright however the program is not returning any data. This is the same format as my actual code. Why this might be happening?

Java Code:

public static void main(String [] args) {
SecondClass object = new SecondClass();
object.setName("Name");
object.getName();
} mh_sh_highlight_all('java');

Java Code:

public class SecondClass {
private String name;
public SecondClass(){
name = " ";
}
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
} mh_sh_highlight_all('java');

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Feb 18, 2015

Regarding return statements within methods. So I have a method containing try and catch block (as required) and much like when you have an if else statement... I noted you have to return an object for both the try and catch blocks. Now in my case my method should return a List object.

The way I have tried to overcome this:

- I've initialised a List object to null as an attribute of the class I'm working in.
- Therefore in the catch block would just simply return the null List object, where as the try block would return the non-empty List (which is what I want).
- I then just test to see if the List != null, when the method is invoked... and that is that.

However the method always seems to return null (when it shouldn't).

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Overload Methods Returning Average?

Oct 8, 2014

I am stuck on this part of my assignment. When the answer prints out at the end, the calculation of average is incorrect. This is what the assignment wants:

Write two overloaded methods that return the average of an array with the following headers:

public static int average(int[] array)
public static double average(double[] array)

Write a test program that prompts the user to enter ten double values, invokes this method and displays the average value.

public class Week7Arrays2 {
public static int average(int[] array) {
int sum = 0;
int average = 0;
for (int i = 0; i < array.length; i++) {
sum = sum + array[i];

[code]....

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Apr 6, 2015

This simple program should build a new table with random values and on the getValue method (perhaps called from othe TestClass) return back content of particular cell. why my getValue method doesn't work. Nay! It returns error while compilation.

import java.util.Random;
class TablicaIntowa{
public int getValue(int a){
return tabl[a];
} //getValue method end

[Code]....

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Returning Values From Arrays

Nov 22, 2014

I have created a class and a matrix of doubles (or at least, I think I have, that's partly what I want to verify).I need to return the values of the array,Here is my class:

public class example{
double[][] Position=new double[2][11];
double calculate(){
for (int time=0;time<=10;time=time+1){
Position[1][time]=time;
Position[2][time]=time+1;
double A=Position[2][time];
return A;
}
}
}

I am getting the error: "This method must return a result of type double", though to me it looks like I am returning double (A).

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Mar 27, 2014

I want to return multiple values in my EJB query. The query goes something like this:

SELECT SUM(s.sales) SUM(s.cancels) FROM accounts.

To implement this if I write as below:

Query query = _em.createNamedQuery("Accounts.findAccountData");

Now if I do query.getSingleResult(); how do i retrieve both the values since the ejb finder returns either a single object or a collection?.

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Apr 9, 2014

I am reading value from database but my problem is am get sql statement values instead of values in database.
 
My code is ....

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Created Tree Lemur Object - Returning Null Consistently From Methods

May 24, 2015

The question pretty much says it all, but I tasked myself with creating a program about lemurs. There are multiple class files in this program. In the below code snippet, I have my TreeLemur.class which extends to the Lemur.class which extends to the Mammal.class. However, when I create a Tree Lemur object in the main program, it is returning null consistently from certain methods. What am I doing wrong here?

TreeLemur.class :

public class TreeLemur extends Lemur {
private String groupSize;
private String diet;
private String fur;
public void setGroupSize() {
groupSize = "
Group Size: Large";
}

[Code]...

As of yet, I'm just trying to get Tree Lemur working properly to continue with creating the other if-branches within the main program.

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Passing Values To Different Methods?

Mar 1, 2015

I am trying to pass the values for UPPER_BOUND and LOWER_BOUND from the main method into the getValidNumber method. However, I'm not sure how to do this. The rest of the code is correct as far as I know, I just need to get the values for the bounds into the getValidNumber method. How would I do this? the notes in the main method explain what I need to do.

public static void main(String[] args) throws FileNotFoundException {
Scanner kb = new Scanner (System.in);
final double LOWER_BOUND = 0;
final double UPPER_BOUND = 100;
//Call the getValidNumber method, passing it the values LOWER_BOUND and UPPER_BOUND.
//Take the returned value and store it in a variable called num.
//Print out the value of num (here in the main method)
 
[Code] .....

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Passing Values To Methods?

Apr 30, 2014

I'm supposed to write a program that reads in 20 numbers stores them into a one dimensional array and then create a method that will calculate the average of the numbers in a separate method.

I've written a for loop in the main method that will take in the numbers but now I need to know how I can pass those values to a method that will calculate the average.

public class ConstructorHomework {
private static double average; //Declaring the Global Variable
//This Method Calculates The Average
public void avg(int x){
average = x/20;

[Code] .....

This is the main method an it contains the for loop that will take in 20 numbers

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
final int size = 20;
double[] array = new double[size];
for (int i = 0; i < array.length; i++){
array[i] = input.nextDouble();
}
//

Here I was trying to create and object and use it to pass value to the method

ConstructorHomework a = new ConstructorHomework();
a.avg(); //Problem is that I don't know what to put in the brackets
a.showNum();
}
}

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Modify Values In Fields In Serializable Object Using Objects Set Methods Java

Dec 10, 2014

This program is basically complete. It compiles and runs. It is a college course assignment that I pretty much completed but for the last part in which I'm suppose to change the values of all fields and display the modified values using a toString method. Modifying the values of the fields is where I am stuck. I don't think I need to create a new text data file to do this. The instructor only asked that all the values of fields be changed and this was the last part of the assignment so I don't think it involves creating additional ObjectOutputStream and ObjectInputStream objects. I'm getting a NullPointerException error on line 161.Here is the code. I'm also including the input data file.

//create program so that objects of class can be serialized, implements interface Serialiable
//create constructor with 4 parameters with accompanying get and set methods, Override toString method
//create text file with 5 records, create Scanner object,ObjectOutputStream, and ObjectInputStream
//create new ItemRecord object, change values of all fields in ItemRecord object using object's set methods
//modify ItemRecord object using toString method

[hightlight =Java]import java.io.Serializable;
public class ItemRecord implements Serializable

[Code] .....

This is the error message:

----jGRASP exec: java ItemRecordReport

Item Cost Quantity Description
Number
A100 $ 99.99 10 Canon PowerShot-135
A200 $149.99 50 Panasonic-Lumix T55
A300 $349.99 20 Nikon- D3200 DSRL
A400 $280.99 30 Sony- DSC-W800
A500 $ 97.99 20 Samsung- WB35F
Exception in thread "main" java.lang.NullPointerException
at ItemRecordReport.main(ItemRecordReport.java:161)

----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.

Here is the data file:
A100 99.99 10 Canon PowerShot-135
A200 149.99 50 Panasonic-Lumix T55
A300 349.99 20 Nikon- D3200 DSRL
A400 280.99 30 Sony- DSC-W800
A500 97.99 20 Samsung- WB35F

Here is the data file for the modified field values.
B100 98.00 10 ABC1010
B200 97.00 15 DEF1020
B300 96.00 10 GHI1030
B400 95.00 05 JKL1040
B500 94.00 01 MNO1050

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Store Pixels Values Currently On Screen And Compare Them To Values On The First Frame?

Aug 29, 2014

I need a way to store the pixels values currently on the screen and compare them to the values on the first frame. Right now I'm using glreadpixels as follows:

currentBuffer= BufferTools.reserveByteData(mapSize);
glReadPixels(mapStartX, mapStartY, mapWidth, mapHeight, GL_BLUE, GL_UNSIGNED_BYTE, currentBuffer);
for (int i = 0; i < mapSize; i++) {
if (currentBuffer.get(i) != baseBuffer.get(i)) {
//Do nothing
continue;
}
//Do something
}

This works perfectly fine but turns out to be a real bottleneck, dropping the fps to a third of what it was. Is there any quicker way? All I'm after is speed, I don't even need to show it on the screen if the comparison is made "behind the scene".

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Why Method Is Not Returning A Value

Apr 29, 2014

I'm new to Java and I have a problem with a method, I can't see the code of the method, I just have a jar, but it should return a boolean, something like this:

boolean band = false;
band = TestClass.testMethod("blabla");
// band = false

The problem is that the method seems that is returning nothing (band remain false), and if I initialize band to true:

boolean band = false;
band = TestClass.testMethod("blabla");
// band = true

band remain true, in other words, the value of band is never modified, the question is, how is this possible? because it should return the same value on both calls, true or false, no matter the initial value of the variable that is receiving the returning value of the method.

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Feb 27, 2015

I have a question in mind that this is my registration form. I am sending these values from HTML form to server and database. I have question that in my case if I click next to Add Another Mobile no in HTML.then a block is genereated and each time a new name is generated.

My Question is if I click 6 times then 6 name attribute are generated. How can I send and differentiate them on my server side.

Because at their I will use something request.getAttribute("Attr_Name");

But they are same. How to do this?.

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Returning A Result And Then Using It In Main

Jan 4, 2015

I've made a class called Car with a method which will tell me a category for the engine size regarding the actual size (which I've included in the main just so I could see if it works) but everytime I test it I get an error.

public class Car {
public String b;
public String c;
public double es;
public double cs; 
public String getCategory() {
if (es < 1.3)

[Code] ....

Figured it out. Was missing parenthesis on audiCar.getCategory();

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May 14, 2014

i am trying to run a command in terminal the code is below if i run the command in terminal it works fine however when i run it from netbeans with code below nothing gets printed. however if i run a different command such as (ip addr) it works fine?

public static void a() throws IOException{
ArrayList lister=new ArrayList();
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("ps -ef | grep firefox");// the command i am trying to run to get pid of application
InputStream stderr = proc.getInputStream();

[Code] ....

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Oct 12, 2014

I am writing a code where in the first method the question will ask whats your favorite website. for example www.javaprogrammingforums.com...when it outputs it will read just "javaprogrammingforums" without the www. and the .com.

Because the program will ask a series of questions in the main, I would like website question to be returned to the main. Here is my code, and what can I do?

import java.util.Scanner;
public class chapter3 {
public static String website(Scanner kb) {
String website;
System.out.println("What is your favorite website?");
website = kb.next();

[Code] ......

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Returning Data From A Constructor?

Sep 1, 2014

I'm having an issue returning data from a constructor. This is an assignment, and the specifications were that two classes are to be used, one for the variables and assigning methods, and one for the main method and the printing. This app compiles, but returns "0" for the isbn number, and I'm sure it's because I'm not doing something right with my constructors. My code is below

public class Book {
/* Declare Variables */
public static int isbn;
/* Constructor */
public Book (int isbn) {
isbn = 454545;

[code]....

There are other variables to add, but if I can get one working, I can get the rest working.

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Jul 15, 2014

For some reason my code returns the memory address of the array when its a print statement with a string, but it works fine when its in a separate print statement all by itself. Why? Do I need to create a toString method that converts a char array to a String to something? The reason why I ask that is becuase on Eclipse line 10 has a warning stating "Must explicitly convert char[] to a String".

public class Ex {
private String word;
public Ex(String word) {
this.word = word;
}
public char[] Display(){
char[] wordChars = this.word.toCharArray();
return wordChars;

[Code] .....

Result:

Hello world
The word is: [C@1db9742

I also tried this, knowing that it's a long shot, but that didnt do anything...

public String toString(){
Ex ex = new Ex(this.word);
char[] word = ex.Display();
String updated = word.toString();//counter intuitive?
return updated;
}

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Jan 7, 2014

I have a for each loop that outputs the Mechanics salary for the first team in the arraylist, how can I add these figures together instead of having separate value for each?The code in my testing class to get the salary for mechanics:

Java Code: for (Mechanic str1: formula1.get(0)){
System.out.println(str1.getSalary());
} mh_sh_highlight_all('java');

How can I also get the salary for the driver 1 + 2 in the same team and add their salary to this? I have attaached an image showing the classes/fields created

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Apr 10, 2014

public int[] allIndicesOf(E itemSought) {
ArrayList<Integer> toUse = new ArrayList<>();
for (E anArray : container) {
if (anArray.equals(itemSought)) {
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[Code] ....

I have an array list of strings. I want to be able to return an array of integers telling me which indexes in the string array list contain the itemSought object.

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Sep 25, 2014

I am working on a project which manages an airport's airplanes and flights based on user input. The method printFlights() - lines 133-134 - is returning null and I can't figure out why. The method is supposed to print information about each flight. The logic is identical to the printPlanes() method which is working successfully.

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May 13, 2014

Write a method that accepts an array of Strings and a character c. The method must return the count of all cs in the strings of the array.

Here's what I have written:

[
public int countC(String[] strings, char c) {
int count = 0;
for(int i = 0; i < strings.length; i++) {
for(int j = 0; j < strings[i].length(); j++) {
if(strings[i].charAt(j) == c) {
count++;
}
}
}
return count;
}]

Does this look correct?

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Jun 16, 2014

When I try to getNextMailItem,it keeps returning null.Why?

public class MailServer
{
// Storage for the arbitrary number of mail items to be stored
// on the server.
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/**
* Construct a mail server.
*/
public MailServer()

[Code] .....

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