Working On A Program That Creates Array From A File
Feb 19, 2015
Working on a program that creates an array from a file, organizes it in various ways, and then prints the results. Right now I'm specifically having trouble with the printAry() method - when I try to run it, I receive a NullPointerException for the active line in printAry() (EDIT: line 102). Not sure which sections are important to this, so I will include the client class and most of the service. I realize that the amount of documentation I included is not necessary, but it is required for the class.
class Lab3StudentAryService
{
private int count;
private Lab3StudentData [] studentAry = new Lab3StudentData[50];
/*
@param: none
@return: none
reads file and converts to array.
*/
public void fillAry() //constructor
{
Scanner scan = new Scanner(System.in);
So I was going to try to create a program that prompts input and creates a file (That didn't exist before) with that input as name.Then, the program prompts inputs after stating questions such as 1 + 1, then if the user inputs an answer, put "Question # = Correct "or" Wrong.Code SO Far:
Java Code:
import java.io.BufferedReader; import java.io.File; import java.io.InputStreamReader; public class File_Read { public File_Read() {//File_Read is the Interactive object
[code]....
So that it puts the Correct or Wrong into the file.
This is a college course assignment that consists of classes TotalSales and TotalSalesTest.In the main program I have created a two dimensional array to output a columnar layout with cross-totals in 4 rows and 5 columns. This program outputs sales totals by row for each sales person(1 - 4) and output by column for products(1 - 5). I have created extra elements in the array to store total for rows and columns. So far both classes compiles. The problem is that although the PrintWriter creates a notepad file, it doesn't print to it. I don't seem to understand the input and output methods completely. I finished another program similar to this using basically the same try and catch that read the file and printed out a document in notepad. Here is the code and I'll try include the input file.
import java.util.Scanner; import java.io.*; public class TotalSales { private int salesPerson; //declare class variable private int productNumber;//declare class variable
public class Car { //instance variables ---------------------- private String make; private String model; private int year; private double vehiclePrice; private double downPayment; private double milesPerGallon;
[code]....
I created this class "Car" (also not sure if it's correct) and need to write a driver program that creates two instances of the class Car. One must use the default constructor, and the other must use the non-default constructor. It must demonstrate the methods used in the Car class using those instances.
public class DriverCar { public static void main(String[] args) { Car car1 = new Car("Toyota", "Corolla", 2013, 20000, 3000, 35); Car car2 = new Car("Ford", "Taurus", 2005, 14000, 1500, 25); System.out.println(car1);
So I want to write a constructor that creates a new object with the data from the array values. I don't know where to start. It's the last method in the code:
public class Measurements { private double[] values; private double[] newArray; private int n; //numberofvalues private double[] ms; public Measurements(int max) { //constructor
-Create a main method declares and creates an integer array called nums that can hold 15 integers.
-Use a for loop to fill that array with multiples of 3: 0, 3, 6, 9, etc.
-Then use similar for loop to print each value in the array on one line, with each value separated by a single space.
-Compile and run the program to see the result:0 3 6 9 12 15 18 21 24 27 30 33 36 39 42
As you write other methods, you'll also modify the main method to make calls to them. The printArray MethodWrite a method called printArray that accepts an integer array as a parameter. This method does not return a value, and must be declared as static so that the main method can call it. Instead of printing the array in the main method, move that loop into this method. Call the printArray method from the main method. Compile and run the program to verify it prints the sam result as before.Add a println statement so that after printing the array values on one line, it then moves to the following line.Finally, modify the loop in the printArray method so that, instead of using a traditional for loop, it instead uses a for-each loop. Compile and run the program again.
Part III: More Array Methods
The linearSearch Method In lecture we looked at a method that performed a binary search on a sorted array. A much simpler (though much less efficient) search is a linear search, that simply starts at the front of the array and looks at each element in turn until it finds it or reaches the end.Create a method called linearSearch that accepts an integer array and a single int value as parameters. The goal of the method is to find the second parameter (the target) in the array. The method should return a single int representing the index of the target value. This method should not print any output itself. In this method, use a traditional for loop to scan through the elements in the array. As soon as you find the target value, return the index of that value.
If you scan through the entire array without finding the target value, return a -1.Modify the main method to call the linearSearch method and print the results. Call it twice, searching for the value 18 (which it should find) and the value 10 (which it should not). Including the previous activity, the output of the main method should now look similar to this:0 3 6 9 12 15 18 21 24 27 30 33 36 39 42
The index of 18 is 6
The index of 10 is -1
The sumArray Method
The sumArray method should take an integer array as a parameter and return a single integer representing the sum of all values in that array.Use a for-each loop to access each value in the array and compute a running sum. After the loop, return the total.Call the method from the main method, producing the following augmented output:0 3 6 9 12 15 18 21 24 27 30 33 36 39 42
The index of 18 is 6
The index of 10 is -1
The sum of this array is 315
The addValue Method...The addValue method should accept an integer array and a single int as parameters. The purpose of the method is to add the second parameter to EACH value in the array. The addValue method does not return a value, but the elements inside the array will be modified. Call the addValue method from the main method, adding 100 to each element in the array. Then call the printArray method again to see the modified array values:0 3 6 9 12 15 18 21 24 27 30 33 36 39 42
The index of 18 is 6
The index of 10 is -1
The sum of this array is 315 100 103 106 109 112 115 118 121 124 127 130 133 136 139 142
Test a Different Array..Finally, duplicate the content of the main method to perform similar tests on another array. Instead of filling it with multiples of 3, fill it with multiples of 4. And instead of using an array size of 15, use an array size of 20.Modify the values search for to include one that is in the array and one that isn't.Rerun the main method and carefully check the results.If you haven't been doing it all along (which you should), make sure the appropriate class and method documentation is included.When you're satisfied that all methods are working correctly, modify the main method to delete the second array tests.
I have the following program. In a nutshell, I creates an array of 3 consecutive ints and the user has to guess what those numbers are, knowing that they are between 0 and 7, this is from Head First Java. In the book, the code has a bug that is made on purpose and they challenge you to fix it. As you can see bellow, every time a user's guess matches a int in the array, the NumOfHits is increased by one. When the NumOfHits is 3 (the length of the array) the game finishes.
The bug is that if you guess 1 and 1 is in the array, if you type in 1, 3 times, I will increase the NumOfHits 3 times and end the game as if you had won. To solve the bug, you need to find a way to tell the program that if the user already guessed that number, it should no longer be taken into account and we shouldn't increase the NumOfHits if the same number is provided.
I "fixed" this by searching for the index of the number that matches an int of the array, and changing that index's value to 100, since the user knows that the numbers are between 0 and 7, they will not submit 100.
The result? If the user submits 2 and 2 is in the array, the value of its indexed is replaced by 100, so that if the user submits 2 again it doesn't count as a match.
Please see the comments in the code
import java.io.*; import java.util.Arrays;
class DotCom{ int NumOfHits = 0; int[] LocationCells; public void setLocationCells(int[] locs){ LocationCells = locs;
[Code] .....
The code works, but for some reason, some times I get a ArrayIndexOutOfBoundsException run time error and it appears to be somehow random. This is what I saw on the command line earlier
C:Userspablo.alvarez>java launchDotCom
Enter a number: 3 missed Enter a number: 4 hit Enter a number: 5 hit Enter a number: 7 missed Enter a number: 5 missed Enter a number: 4 missed Enter a number: 3 missed Enter a number: 4 missed Enter a number: 5 missed Enter a number: 6
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1 at DotCom.checkYourSelf(launchDotCom.java:16) at DotComGame.startGame(launchDotCom.java:59) at launchDotCom.main(launchDotCom.java:72)
As you can see here, 3 returned 'missed' but 4 and 5 returned hit. Since the numbers are in sequence and are only 3, it makes sense that the last number is 6 (4,5,6). You will then notice that when I submitted 3 and 4 again it returned 'missed' as expected, because the numbers were already matched earlier, but then when I submitted 6, it returned the error seen above.
Sometimes this doesn't happen at all, sometimes it happens at the 2nd guess or third, it appears to be somehow random. I'm familiar with the error message, but I don't see where I'm using an index that doesn't exist in the array. The only time I'm referencing an array index is on
LocationCells[index] = 100;
but the index variable will only hold a value if the int submitted by the user matches on of the values in one of the indexes, so how is it that I'm going over the number of available indexes?
The main method will drive your program by doing the following:
-Create an array to hold all the individual golfers and par scores (type is Golfer[ ]). -Prompt the user for a data file containing the Par scores and the player names and score. The format of the input file should look like
import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.Random; public class FileHandlingDemo {
[code].....
As you can see my Intention is to save randoly generate Integer in the output file And this is not working but if I use Something like this
import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; public class FileHandlingDemo {
[code].....
it's working fine reading that from Input.txt and writing that data in output.txt file. but not in first case Both file are in working directory already created.Where is wrong?
My instructor gave me this code to use as my Array sort. I can not get this to work. I do not get any compile errors, the code just does not do anything.
Java Code:
package inventoryprogram4; import java.util.Scanner; public class Inventoryprogram4 { static GUI mainGUI = new GUI(); static String outText = "";
I am working on a contact list program with a GUI for a school project.I'm running into all kinds of issues when trying to update the JList in my GUI which displays the contacts.I think my issues are being caused by a lack of synchronization between the contact list that stores the data, and the contact list that is being displayed.I've tried all kinds of getters and setters, passing array indexes, passing array member objects etc.
General rundown of how I want the GUI/Code to work: When I select an object in the JLIst, the fields on the right should display that objects information.When the "Add Contact" button is created, a new blank contact should be created and added to the Contact List, and then displayed in the JList.When a field on the right side of the GUI is updated, the object in the contact list is updated simultaneously (using document listener), and therefore the JList would also be updated.
Here is the program I wrote for calculating the circumference of a circle.
//circumference.java //program that calculates the area and circumference of a circle import java.util.Scanner; //program uses class scanner public class circumference{ //main method begins execution of Java application public static void main(String args[]){
[Code] .....
Even though my code compiles and runs without any errors, the program doesn't calculate the circumference.
Alright so I'm trying to write a code that implements a for loop and if statements that displays any number from 100-200 if the number is divisible by either 5 or 6 in rows of ten numbers each row. If it is not divisible by that number then it should go back to the beginning of the loop until it reaches 200. My main problem is that it doesn't display anything. I don't get any errors or anything but every time I run the program it just displays nothing. Sample output is at the bottom of the code.
public class Exercise5_11 { public static void main(String[] args) { int count = 0; int i = 100; //for (the numbers from 100 to 200) for (i = 100; i>100 && i<200; i++){
I am currently writing two java classes (client and server). The client takes an input number form keyboard and sends it to the server. The server then multiplies this number by two and sends it back to the client. The numbers should also be printed to screen along the way, for example if I input the number 3 I should get
"From Client: 3" "From Server: 6"
They should continuously do this unless a negative number is received by the client, say for example the number -3 is sent to the server and it returns -6.
The code I have for the two classes so far is:
import java.io.*; import java.net.*; import java.nio.ByteBuffer; import java.util.Scanner; class Client { public static void main(String args[]) throws Exception { DatagramSocket clientSocket = new DatagramSocket();
[Code] .....
Currently, when I run the program all I get is an output of the number first entered. I am aware it requires a loop but I don't know where and what the condition should be.
Also if I wanted to adapt this so that it would take the integer from client and subtract two at the server and return to client who sends back to server to keep subtracting two unless it reaches a negative number at which point the client will terminate the program - how might I do this.
I do realise there needs to be a while loop in the above code, but I wanted to test it sent the number from client to server and its not doing it. All I get is a print screen of 'enter number' and then the number I enter.
My code is supposed to give the array index on the left and what is inside the array on the right, but i get nothing except the header? I am using eclipse.
public class Options{ public static void main(String args[]) { System.out.println("Index Value"); int value[] = {1,2,3,4,5}; for(int add = 0 ; add <value.length ; add++) { System.out.println(add + " " + value[add]); } } }
I don't know why, but my binaryStringSearch method isn't correctly printing even though it's virtually the same thing as my binaryIntSearch method, which works perfectly.This is the objective of the exercise:
1) Use binary search to output the position of the following numbers from file numsearch.txt
5, 9, 43 and 79.
2) Read from file namesearch.txt
Use binary search to output the position of the following names Dennis, Billy-Bob and Steve.The file contains 20 entries.
Whenever I enter a column number to drop a checker, the program immediately stops running and gives me a "java.lang.ArrayIndexOutOfBoundsException" and points to my checkWinner method. There are two int constants, one is LOWEST_ROW_INDEX = 5, and the other is RIGHTMOST_COLUMN_INDEX = 6. I cannot figure out what to do differently with my checking algorithm to stop this from happening.
public static String checkWinner(String[][] gb) { //tests for a horizontal line made by four of the same color checker for(int row = 0; row <= LOWEST_ROW_INDEX; row++) { for(int col = 0; col <= RIGHTMOST_COLUMN_INDEX; col++)
I have added a Simple Jar file in Eclipse Proect->BuildPath->jar file but class Inside that are not showing in My project this is my Project Structure and I have all ready checked in Order and Export..But jar file is not working.
My Computer Programming teacher has given the class a problem that requires the use of var.charAt(), var.length() and while/for. Basically, the problem is that we have to create program that'll show a mirrored or reverse version of the entered word. Like for example, if your input is the word "Hello" (the quotation marks aren't included), the output will be "olleH".
Here's the code:
import java.io.*; public class StringMirror {public static void main (String [] args) throws IOException {BufferedReader scan = new BufferedReader (new InputStreamReader(System.in)); String enteredWord = ""; int lengthOfTheWord = 0; int lengthOfTheWordMinusOneVersion = 0;
[code]....
It is working, but the problem is that after the output, there's this error that says String index out of range: -1.
the program is working but I kind of wanted it to have no errors in the end.
public class AddArray { public static void main(String[] args) { int sum = 0; sum = addArray(myarray); System.out.println(" hello"); System.out.println("This program will create an array then pass the array to an method to be totaled"); int myarray[] = new int [6];
I want to make a method that takes a word and then checks if the word can be created from available letters. For example, if a word "johnson" can be created by using letters "jashoqwnon".
Now my goal is to make sure that if available letters contain a letter from the word, that letter is put into a String called result and then erased from the list of given letters. So, "johnson" and "jashoqwn" would produce the result "johns" and leave "aqw" unused.
Now the problem that I am facing is that I can't get Java not to use the same letter twice. So "johnson" and "jashoqwn" still gives "johnson".
I've tried everything in my power but I am missing something. Here is my code.
public static String makeAWord(String word, String letters){ String result = ""; for(int i = 0; i < word.length(); i++){ for(int j = 0; j < letters.length() ; j++){
I have a JPanel class that creates a left panel and a right panel. the left panel and right panel both have one button each. What I’m trying to accomplish is when I click on the button in the left panel that it updates the button in the right panel. I have to do this without changing anything in the right panel.Basically I have to have LeftPanel have a way to keep track of an instance of RightPanel and I would have to do this through the JPanel class. But I have no clue where to begin on even accomplishing this.
I've written a die program, and i want the user to type any key in order to continue, how do i achieve this ?
I have already created a Die class, i just want to implement the main method now.
PHP Code:
package test;
/* This program demonstrates the use of a user-defined class
public class RollingDice { // Creates two Die objects and rolls them display the values. public static void main (String[] args) { Die die1 = new Die(); System.out.println("Roll the die ") } } mh_sh_highlight_all('php');
What should i add after System.out.println, So that the user types (any key, or types "Enter" for example, for the die to roll). i dont want the die to roll by itself i Want the user to interact with the program in order for it to roll.
