I/O / Streams :: Reading From And Writing To A File Then Read Again Including Data Written
Oct 11, 2014
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
When I am trying to read data from BufferedReader and writing into excel using FileOutputStream object with POI APIs then i am getting the data in excel file in bad formats. you can check the log file and excel file attached for more information.
Here my problem is I cannot use BufferedWriter in place of FileOutputStream because POI class XSSFWorkbook only have one write method and we can only pass FileOutputStream class object there.
I need to print contents of database to excel file.Apache POI is the solution but I am not finding a way to print the DB column names/headers into the excel.
E.g.:
incase csv we have opencsv CSVWriter writer = new CSVWriter(new FileWriter(fileName)); System.out.println("writer"); writer.writeAll(rs, true);
will print the db contents with the column headers dynamically whatever the query may be.
Any solution where we can print data and column names without know the query previously as we are getting query at the run time and each time the query is different.
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.
I 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;
I am looking for a pure java api that can read metadata from an mp4 file, I have looked online but all apis I found are wrappers to native code. How to read mp4 with java .....
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?
I 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:
I'm getting an IllegalArgumentException returned when I try to get a file using guava library.
I previously had the function working when the file was in a different location, before I switched to running JBehave, my steps run but it fails to find the resource, even after I've moved it.
The code being executed is (this worked previously before using JBehave):
The file I'm looking for is in the root folder for src/main/resources and also src/test/resources, previously I had it within a completely different location before I switched over to JBehave. I've tried it within a subdirectory in the same locations too.
I've recently updated the pom.xml to try to include the location required.
I am creating a program where it reads the data inside a file and then places this data into arrays. The file I created has numbers 1-30 in it, file named, testing1.txt .
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:
I 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();
My code below creates the 2 files successfully, but it is not able to write the sample data into the newly created file. I can't figure out the reason why.
Another strange thing is that when I tried inserting System.out.println calls for debugging, nothing prints out.
If I want to read my file line by line and when it hits a certain value from that point it should start deleting the lines until the tag ends.Just curious will my code actually work at the moment or not because it goes through so many times then goes straight back to the variable declarations at the start of the method and never hits the console print line.
public void removeEnvironment(){ //declare variable to environment id String environmentID = "Environment id"; String lines = null; boolean lineFound = false; boolean end = false;
New to programming. Am supposed to create a program that reads a text file (of integers) and computes a series of computations on these integers. I don't have the code for the integers in my code yet, (i know how to do those), but am struggling getting the array to simply print in the print writer. I have the user select a text file, read the file with a scanner, and then save the computations done from my code into another file. specifically, the problem is as follows: Write a program that uses a file chooser dialog to select a file containing some integers. The file contains an integer N followed by N integers. The program then uses a file chooser dialog to let the user specify the name and location of an output file to write results to.The data written to the output file will be as follows
(1) The original list of N numbers from the input file, (2) The original list of N numbers printed in reverse order of how they appear in the input file. (3) The sum and average of these numbers, (4) The minimum of all the numbers, (5) The maximum of all the numbers.
I can read the data to a monitor perfectly. But, I'm having problem reading data from an external file into an array of class objects. Here's my attempt at writing the method:
private void openFile() //This method asks the user to enter a file name(including the file extension) and then //Sets the data to an array of Product type { String fileName, storeName="", emptyLine1="", emptyLine2="", name="", productName=""; int demandRate=0; double setupCost=0.0, unitCost=0.0, inventoryCost=0, sellingPrice=0; Scanner inputStream = null;
I have to read data from a text file and print it in a new text file. An example of one line is like this: Johnson 85 98 75 89 82
I then have to take the average of all the numbers and assign a "grade" to the numbers for each line of the text file and make a new file so it looks like this for 10 lines:
Name 1 2 3 4 5 Average Grade
Johnson 85 98 75 89 82 85.80 B
My problem is extracting the data from the file so I can use it.
