I was writing a method to read a file. I did not think it through and gave the return type as void and modifier as static but I am not sure if it has to be void. How do you decide the return type of the method? Is there a good rule of thumb in such cases? Also, does the use of static needs to be done sparingly?
View RepliesI have problem with writing objects to file. The thing i want to do is write object(Measur) and then read it from Notepad++. Not from program, but normally from computer. When i'm opening my file i see patterns(i dont how to call this). I think, that I need write it as a string in some way. There is my code:
Java Code:
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
class Task3 {
[code]....
I'm having a bit of trouble with using the Scanner and the Printwriter. I start with a file like this (1 = amount of Houses in the file)
1
FOR SALE:
Emmalaan 23
3051JC Rotterdam
7 rooms
buyprice 300000
energylevel C
The user gets (let's say for simplicity) 3 options:
1. Add a House to the file,
2. Get all Houses which fullfil requirements (price, FOR SALE / SOLD etc.) and
3. Close the application.
This is how I start:
Scanner sc = new Scanner (System.in);
while (!endLoop) {
System.out.println("Make a choice);
System.out.println("1) Add House");
System.out.println("2) Show Houses");
System.out.println("3) Exit");
int choice = sc.nextInt();
Then I have a switch for all of the three cases. I keep the scanner open, so Java can get the user input (house = for sale or sold, price = ... etc). If the user chose option 1, and all information needed is inputted and scanned, the House will be written to the file (which looks like what I typed above).
For this, I use try (PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("Makelaar.txt", false)))). This works perfectly (at least so it seems.)
If the user chose option 1, and all requirements are inputted and scanned, the Houses will be read (scanner) from the file and outputted. For this I use the same Scanner sc. This also works perfectly (so it seems atleast).
My problem is as follows: If a House has been added, I can only read the House(s) which were already in the file. Let's say I have added 2 houses, and there were from the start 3 houses. If option 2 is chosen, the first 3 houses will be scanned perfectly. An exception will be caught for the remaining 2 (just added) Houses. How can I solve this? I tried to close the Scanner, and reopening it, but apparently Java doesn't agree with this
I am kind of new to programming in java and I am trying to run a first time setup type of thing for my program so I am saving the settings to a file. If the file doesn't exist I want it to run the first time setup but if the file does exist I want it to skip that process. My problem is that .exists() says reads true whether the file is there or is not there.
public static void main(String[] args)throws IOException{
new Window(); //Runs the Window()
PrintWriter writer = new PrintWriter(path);
boolean bool = new File("path.txt").exists();
System.out.println(bool);
if(!new File("path.txt").exists()){
[Code] ....
I have to write a method called censor that gets an array of strings from the user as an argument and then returns an array of strings that contains all of the original strings in the same order except those with length of 4. For example if cat, dog, moose, lazy, with was entered, then it would return the exact same thing except for the words with and lazy.
Currently, my code so far just prints [Ljava.lang.String;@38cfdf and im stuck.
import java.util.Scanner;
public class censorProgram {
public static void main (String args[]){
Scanner input = new Scanner (System.in);
System.out.println ("How many words would you like to enter?");
int lineOfText = input.nextInt();
[Code] ....
I have to make new string array in the method and return words without four letters in the main method
Okay so I have to write a method to compute the following series: m(i)= 1/3 + 2/5 +....+ (i / 2i+1) and write a test program that displays a table " i = m(i)" 1=0.3333 2=0.7333....all the way down to 20 which is 9.2480. I have written something and cannot seem to get the sum of the fractions to display .
public class ExtraCredit1
{
public static void main(String[] args)
{
double num;
double sum = 1;
[Code] ....
import java.util.Scanner;
public class Project_5
{
public static void main (String[] args)
{
Scanner input= new Scanner (System.in);
[code]....
So I'm attempting to have this program take the users input of integers, pressing enter in between each one. If they enter a negative number it lets them know that its invalid. At the end of the program it takes all of the valid integers entered and must add them and average them. I've put the final println in there as a placeholder. If the user types in "6" then presses enter and types in "3" , the output is:
There were 3 valid numbers entered.
The sum of the valid numbers was --- and the average was ---.
There were 0 invalid numbers entered.
It then continues on allowing the user to enter more values. Here is the example output for correct code"
Enter a positive value (EOF to quit): 4
Enter a positive value (EOF to quit): 7
Enter a positive value (EOF to quit): 8
Enter a positive value (EOF to quit): 2
Enter a positive value (EOF to quit): -1
The number "-1" is invalid.
Enter a positive value (EOF to quit): 8
Enter a positive value (EOF to quit): 0
Enter a positive value (EOF to quit): -4
The number "-4" is invalid.
Enter a positive value (EOF to quit): CTRL-D
There were 6 valid numbers entered.
The sum of the valid numbers was 29 and the average was 4.83.
There were 2 invalid numbers.
I am currently working on a java project, this involves me writing some code for a project, below are my attempts at coding so far:
/**
* Prints out details of all animal in the zoo.
*
*/
public void printAllAnimals() {
System.out.println("
Details for all animals in Zoo " + zooId);
System.out.println( "==================================");
[code]....
I currently cannot get the printallanimals() method to work as it should when executing the method printallanimals it just opens a filedialog box, when it is suppose to use the Collection object c,so that animals stored in the zoo can easily be checked.
I had to write a class called Thermometer, that has one instance variable (an integer) for the temperature in Fahrenheit. I had to include the following methods
-a constructor that initializes the temperature to 60
-there is a method to change the temperature
-there is a method to display the temperature
-there is a method to reset the teperature to 60
Here is the code for that.
public class Thermometer {
private int temp;
private int thermometer;
public Thermometer() {
thermometer = 60;
[code]....
Now I get to the issue. I have to write a test class called thermometer to test the thermometer class. I need to test each method while displaying the temperature after it. My professor said I should use the invoke method but didn't go into much more detail than that.
The question is write to a method symmetric that accepts a stack of integers as a parameter and replaces the stack contents with itself plus a symmetrical version of itself (the same elements in the opposite order).
For example, suppose a variable s stores the following elements:
bottom [10, 50, 19, 54, 30, 67] top
After a call of symmetric(s),the stack would store the following elements
bottom [10, 50, 19, 54, 30, 67, 67, 30, 54, 19, 50, 10] top
Note that the symmetric version is added on to the top of what was originally in the stack. The bottom half of the stack contains the original numbers in the same order.
If your method is passed an empty stack, the result should be an empty stack.
If your method is passed a null stack, your method should throw an IllegalArgumentException.
a) Write the method symmetric using one temporary stack and one temporary queue.
/> Re-write the method using only one temporary Queue.
What I have done so far is
public static Stack symmetric(Stack s1){
Stack s2 =new Stack();
int theTop=0;
if(s1.isEmpty()){
return s1;
[Code] .....
Its not working.
I'm trying to write an indexOf() method that will return every time a value occurs in a linked list. I need to use my user-created linked list not the built in Java linked list. For example in a linked list of characters: "i, p, z, z, n, d, p, z" when I search for "z" it should return position variables for 3, 4, and 8. Currently what I have is obviously only returning the first instance.how I can return more than one instance?
public int indexOf(char input) {
LLNode currentNode = this.first;
int position =1;
boolean found = false;
[code]...
I am using a FileOutputStream to write a file but it is not writing data to destination file from source
Here is my code
package org.kishor.outputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class WriteToaFile {
public static void main(String args[]) throws IOException
{
FileOutputStream fout = null;
[code]...
find a bug where i am wrong why data is not on output file?
I've looked at multiple sources and everyone is saying different stuff. Which one should I be using? FileWriter/FileReader, other people was saying PrintWriter, and one even said : "Formatter" which is the one I'm doubting mostly. My purposes for writing files is for like saving maps, saving high scores, etc.
View Replies View RelatedI have accountsData.txt file in my default package, this is the file it should be writing to and reading from.
There is an ATM class, which has the main in it. From here the program is supposed to work like an atm, you type in your account number and can withdraw or deposit. It is supposed to then write the changes to the file.
//Read from a file.
public void loadAccounts(String inputFileName) throws IOException
{
Scanner fin = new Scanner(new File(inputFileName));
// Variables to store the values.[/color]
int account = 0;
double balance = 0.0;
[Code] .....
I need to write a program that, when a button is pressed, will add the user input to a table AND write it to a sequential data file. I have everything done accept for how to write the data sequentially(all input data on the same line in the file). The following is part of the code:
private void submitButtonActionPerformed(java.awt.event.ActionEvent evt) {
DefaultTableModel dtm = (DefaultTableModel)jTable1.getModel();
dtm.addRow(new Object[]{donorName.getText(),charityName.getText(),donationAmmount.getText()});
//Adds user input to the table
try
{
FileWriter writer = new FileWriter("FundraisingInformation.txt",true);//Creates file or adds to it
BufferedWriter bw = new BufferedWriter(writer);
[code].....
I would need the file output to be in the following format:
donorName charityName donationAmmount
As I said, using the .write(bw) i know how to make it look like:
donorName
charityName
donationAmmount
I want a servlet to write a file inside WEB-INF folder
I tried these things
File file =new File("feedback.txt");
or
File file =new File("/feedback.txt");
or
File file =new File("WEB-INF/feedback.txt");
I am trying to write a Float Array to a file but it is only writing the last line of the array to a file. I have also attached the entire assignment as a zip file with all required files. Here is the part of the code I am having issues with:
Java Code:
for (int i = 0; i < differenceArray.length; i++){
System.out.println ("Date: "+ dateArray[i] + " Opening: " + dataArray[i][2] + " Closing: "+ dataArray[i][5] + " Difference: " + differenceArray[i]);
try(FileWriter writer = new FileWriter("C: emp" + fileName + ".txt")){
writer.write(Float.toString(differenceArray[i]));
[Code] .....
There are several ways in Java to create a text file and write to it. But which is the most effective way among them? Any example with code?
View Replies View RelatedI am creating a car simulator that simulators the odometer and fuel gauge on a car. I want to print the results to a text file but it seems to be printing only the last two lines instead of all of them. How can I make it so it doesn't overwrite the previous input?
Here's my main method:
public static void main(String[] args) throws FileNotFoundException {
CarInstrumentSimulator carInstrumentSimulator = new CarInstrumentSimulator();
FuelGauge gas = carInstrumentSimulator.new FuelGauge();
[Code].....
I need to read lastname, firstname, and ssn from a text file and sort them based on oneof those three creiteria. Here is my person class:
public class Person implements Comparable {
private String lastName, firstName, ssn;
private static int sortBy = 1;
public static final int LASTNAME=1, FIRSTNAME=2, SSN=3;
public void setSortMethod(int method) {
if(method != LASTNAME && method != FIRSTNAME && method != SSN) {
throw new IllegalArgumentException();
} else {
[code]....
how to sort my info and store it into an array and then write that info into my new file.
How to output text to a file, so I had to do my own research on google, but the results I found were confusing. I finally got my code to write to a file, but I cannot figure out how to append a new line. I know what part of the code is incorrect, but I don't know how to fix it. here is what I have right now:
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Scanner;
public class highscore {
public static void main(String[] args) throws IOException {
[Code] ....
I can see the last two lines are telling the program to overwrite the first input with the second. Of course if I pick a different file name for the second output, I get another file with the second input, but I need to learn how to append as well.
My program creates a file but cannot write to it and i cannot figure out why.
How can i fix this code so that the FileOutputStream writes the String "Output" to the file HighScore.
public boolean ScoreWriter(int HighScore, int ScoreNum){
boolean writ = true;
System.out.println(HighScore + " " + ScoreNum);
try{
File ScoreFile = new File("HighScore");
if (!ScoreFile.exists()){
ScoreFile.createNewFile();
}else if (ScoreFile.exists()){
ScoreFile.delete();
ScoreFile.createNewFile();
[code].....
I'm writing a program to dynamically update an xml file to add, delete, and edit entries in the file. I've run into an issue with the add method because when I write into the file, a random letter is added before the line. EX:
I want to add "<item> ..." to the end of the list of entries, but when it is added, this is what is added "Z <item> ..."The spacing for the <item> is correct, however, I don't see where or why the Z is added.
public static void insertItem(Item i)
{
try {
String insert = " <item>";
String text = "";
Scanner in = new Scanner(file);
[code]....
I obtained the following code online which purports to get the content of the JFrame:
public BufferedImage getScreenShot(
Component component) {
BufferedImage image = new BufferedImage(
winWidth,
[Code] .....
Then I write out the image with the following code:
BufferedImage screenShot = getScreenShot(c);
try{
File outputfile = new File(
[Code] .....
When I double-click on the resulting file, all the images show up as black rectangles in Windows Photo Viewer. Yet the associated buffered image displays correctly in the window. I've tried 'jpg, 'png', and 'bmp' extensions, with matching formats in the write. I am using Win-7 64-bit. and jdk8 with matching jre.
I'm working on a project for class that asks me to record punch-in and punch-out times for employees. However, I am having difficulty figuring out where I am going wrong as none of the information will write to the text file in the ArrayList that I have created. The code is as follows:
import java.text.*;
import java.util.*;
import java.io.*;
import java.nio.file.*;
public class TimeClockApp {
// declare class variables
private static EmployeeDAO employeeDAO = null;
[Code] .....
I want to keep the coding as simple as possible as I am new to Java, and have spent hours upon hours trying to figure this all out. The console output looks like this:
Welcome to the Punch-In/Punch-Out Screen
Please choose an option below:
I. Punch In
O. Punch Out
Choice: i
PUNCH IN
--------
Enter Employee ID:
8
8Punch-In Date & Time: 2014/05/28 22:44:26
[]
Press enter to return to the main screen:
I'm doing this assignment in which i have to write some products in csv file...but as u can see in csv file two products are same "Cooking Oil"..so any method that can add two same product's quantity and their amount and write them in file
import java.util.*;
import java.io.*;
public class SalesbyTransactionMonth{
private static final String fileName = "Data.txt";
private static final String fileName1 = "sales_by_trans_month.csv";
String line = "";
[Code] ....
Attached image(s)