Write Multiple Records To A File - Why Does This Keep Overwriting
Oct 27, 2014
So I am calling this method several times and trying to write multiple records to a file. Problem is that every time I call the method it overwrites the file from before and doesn't add it.
public void fileWriterMethod() throws IOException{
RandomAccessFile raf = new RandomAccessFile(filename, "rw");
raf.writeInt(id);
raf.writeInt(existingMileage);
raf.writeInt(gasCost);
raf.writeInt(ndays);
raf.writeInt(rate);
So I am calling this method several times and trying to write multiple records to a file. Problem is that every time I call the method it overwrites the file from before and doesn't add it.
public void fileWriterMethod() throws IOException{ RandomAccessFile raf = new RandomAccessFile(filename, "rw"); raf.writeInt(id); raf.writeInt(existingMileage); raf.writeInt(gasCost); raf.writeInt(ndays); raf.writeInt(rate); raf.writeInt(totalCharge); raf.writeInt(discount); raf.writeInt(tax); raf.writeInt(netCharge); raf.writeInt(returnMileage); raf.writeBytes(carName + " "); //Closing the stream raf.close(); }
The assignment is to create a program that accepts entries from a user for 3 variables then saves the data to a file. There are other programs that use the file created. One program displays the non-default records. The next program allows the user to enter the id for the employee and displays the first and last name for that id number. The last program allows the user to enter a first name. It then displays all id numbers and last names for records with that first name.
Given the above situation, I am stuck on creating the first program. I can make the text file and write the information to it. However, when the file is created, a space is placed in between each entry for some reason. I cannot figure out how to get rid of this space so that I can display the appropriate records for the remaining programs. Below is the code and a view of my problem.
import java.nio.ByteBuffer; import java.nio.channels.FileChannel; import java.nio.file.*; import java.io.*; import static java.nio.file.StandardOpenOption.*; import java.util.*; public class WriteEmployeeList {
[Code] .....
The values for nameFormat and lnameFormat are 10 spaces. This is how the book told me to make sure everything is uniform and searchable. The file contents look like this when viewed in notepad.
I am writing to a file coordinates of texts using PathIterator (Java Platform SE 7 ) saved as SVG format i defined the Font attributes using AttributedString (Java Platform SE 7 ) and TextLayout (Java Platform SE 8 ). It is saving to the file and working properly, but it is just writing as a single line of text where is my target is multiple lines of text, i began using LineBreakMeasurer (Java Platform SE 7 ) Class, but some text is removed plus i got single line of text only, where i face the problem that , How to determine the width to get multiple lines of text ? i tried to figure out from this exampleDrawing Multiple Lines of Text (The Java - Tutorials > 2D Graphics > Working with Text APIs) where is drawing multiple lines of text but i am using getBounds().getWidth() of TextLayout object the code i tried
I need to write out multiple BufferedImages to a single tiff file. Each image represents a seismic time slice which can be several megabytes in size. I have used the TIFFEncodeParam.setExtraImages method and saved all my BufferedImages to a vector but my since I create so many BIs I keep running out of memory. Is there a way to create a BI, write it out to a TIFF file, then discard the BI and create the next one?
I do most of my file I/O with {Scanner} for input and {PrintWriter} for output. I've got lots of places in my code that looks like:
Scanner source = new Scanner( new File( sourceName)); PrintWriter dstntn = new PrintWriter( new BufferedWriter( new FileWriter( dstntnName)));
But when I call the constructor for {PrintWriter} up above, it overwrites whatever the original contents of the file designated by {dstntnName} were, doesn't it? Is there a way to call the constructor so that any future writes to it simply append to the original contents, instead of overwriting them?
I am working on a project and for one step, I need to load an array (which in this case, students[]), with the records in another file.
So, should I used the try, catch method?? I am just not sure about the array. I know how to read from a file, but, I didn't get the idea of loading an array.
I am reading records from a txt file and storing it into an array
import java.util.*; import java.io.*; public class PatientExercise { //patients exercise time public static void main (String[]args) throws IOException{ Scanner in = new Scanner(new FileReader("values.txt")); double [] patientTimeRecords = new double [300]; int noExerciseCount=0, numPatients =0; double highest=0, lowest=0, avg=0, totalTime=0;
[Code] ....
However an error msg keeps popping up:
Exception in thread "main" java.util.NoSuchElementException at java.util.Scanner.throwFor(Scanner.java:907) at java.util.Scanner.next(Scanner.java:1530) at java.util.Scanner.nextDouble(Scanner.java:2456) at pastpapers.PatientExercise.main(PatientExercise.ja va:44)
line 44 is:patientTimeRecords[i]= in.nextDouble();
I have written a code to download .csv file with records from DB.
To download records i am uploading a .CSV file containing telephone number.
After downloading the .CSV file page is not getting refreshed.
Below is the code snippet i am using,where i am setting response content type as test/csv.
ServletOutputStream op = resp.getOutputStream(); // Set content type of output resp.setContentType("text/csv"); resp.setHeader("Content-Disposition", "attachment; filename="test""); op.flush(); op.close();
How that page will get refreshed after csv file download or after response.
I'm having trouble getting new objects to add to an ArrayList. Instead, every time a new object is created and added, it overwrites the first object. So if I read in four lines from a text file and make them into four objects, each overwrites the previous and only the last object is printed. I can print out the contents correctly if I move the println statement within the if-loop; however, I need all the objects to saved to the list for searching (later implementation). i believe it has something to do with the instances of the object, but I'm a little confused about how to fix it. Here's the portion of the code I'm looking at:
Java Code:
if (fileChooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) { File file = fileChooser.getSelectedFile(); Scanner scanner = new Scanner(new FileReader(file)); String currentLine; System.out.printf("%-20s %-20s %-20s
What I mean is, I have this set and it is supposed to take out all the duplicates. If I enter aaabbbcccd the output should be abcd, but instead my code just outputs the last word, or in this case letter entered.
import java.util.*; public class setdemo { public static void main(String[] args)
Design a program that will read a file of sales records and produce a sales report. Each record in the file contains a customer's ID, name, a sales amount, and a validated GST code. The GST code is to be applied to the sales amount to determine the sales tax due for that sale, as shown below.
GST CodeGST Rate 0 1 20% 5% 10%
The report is to print a heading "SALES REPORT", and detail lines listing the customer's ID, name, sales amount, sales tax, and total amount due including sales tax.
Is assignment sofar:pseudo code SalesReport Read customer file Get TaxCode Get GSTAmount SalesTax Calculate SalesTax
is my current exercise.so far i have gotten the code to create a file, and ask the user to input their age.what should i use to save what the user writes into the file?
Java Code:
package assignment7; import java.io.*; import java.util.*; public class Exercise2 { public static void main ( String [ ] args ) throws IOException { Scanner scan = new Scanner(System.in);
I have created a program that allows a pizza shop to enter a customers orders (via 3 seperate panels of options), and calculate a total. Everything works just fine, and now we have to take it a step further and record the sale data in a .txt file (which will include the Crust Type, Toppings, and Extras).
I need to make it so that when a user clicks the calculate button, it also writes to a file (in this case, SalesRecords.txt). I have it all set up, but for some reason I can not get it to work. The error I get is:
"error: unreported exception FileNotFoundException; must be caught or declared to be thrown PrintWriter outputFile = new PrintWriter(filename);
Here's my code: (the calculate button that I am working with is indicated by a comment)
[I looked up the exception I got, and just so everyone knows I made sure that the file "SalesRecords.txt" DOES EXIST. It is in the same folder as my java and class files for this program. I even tried defining the absolute file path for SalesRecords.txt and that changed nothing.
For a class, I'm making a prison system program. The prison has cell blocks, each cell block has cells, each cell has bed(s), and each bed has prisoners. There are also visitors and visits. I thought, rather than write all of those to different files, I could just write the entire prison to a file and make all the classes under it implement serializable. The instructor said that is a bad practice and we shouldn't do it. So I'm thinking I'll make the prison non-serializable. But the prison has maps of cell blocks, inmates, visitors, and visits. I think I'll make all those serializable and I'll also make everything a cell block contains serializable as well. Then I can just read the cellblocks from the file. But is that too easy as well? Is that a bad practice?
My program successfully reads a file, reports back what it finds and creates an output file. However, I cannot get it to write to the output file, it is always blank!
Here's my code:
import java.util.Scanner; import java.io.*; public class Ex19 { public static void main (String [] args) { //Variables
I want to write a text area to a file which I have accomplished however the formatting for how it is written into the text file is different. Is there a different library I must use to retain the formatting?
I'm using a BufferedWriter to write to the file
if (!file.exists()) { try { BufferedWriter output = new BufferedWriter( new FileWriter(file)); output.write(textArea.getText()); output.close(); } catch (IOExcception io) { io.printStackTrace(); } }
I extended the SimpleFileVisitor class. And I am able to traverse the file directories. I give a file path then have it display the files full path and out put that to a text file. Here is what i have so far.
public class Main { public static void main(String[] args) throws IOException { Path fileDir = Paths.get("somedirpathhere"); FileTraversal visitor = new FileTraversal(); Files.walkFileTree(fileDir, visitor);
[code]...
I am able to printout of the arraylist to the console. I cant get it to write to a text file whats in the arraylist to a text file.
package shoppingcartselection; import javax.swing.*; import java.util.ArrayList; public class Main { public static void main(String[] args) { ArrayList<Item> items = new ArrayList<>();
[Code] .....
I have it to save to a text file the subtotal, sales tax, and the total cost of all items in the cart after clicking on Checkout. I need it to also show the Items that where in the cart, along with how much each Item costs. I've tried this:
public void save(ArrayList Receipt) throws FileNotFoundException { PrintWriter pw = new PrintWriter(new FileOutputStream("Receipt.txt")); for (Item itemsInCartNames : itemsInCart) pw.println(itemsInCartNames); pw.close(); }
But this is what gets saved to the Receipt.txt file:
I want to write byteArray in file from String and if "/n " newline comes in String it should write from next line in file. I tried and no content starts from newline in file.
Suppose String s= "This is my Java Program /n Converting string to byteArray";
Output in file should be as :
This is my Java Program Converting string to byteArray
When i am converting byteArray in String, it showing me same output as i wants but not in file.it showing me on console.
psvm(String arr[]){ String s= "This is my Java Program Coverting string to byteArray"; FileOutputStream fos = new FileOutputStream("filepath"); fos.write(s.getBytes()); fos.close(); }
output in file : This is my Java Program Converting string to byteArray
Any other way to get content after newline in next line.
