I want to read in a text file(list of Names) using FileReader than Write to another file using FileWriter. Using FileWriter, I only want to write the Name starting with F to a new text file. I have the file reading from one text than writing to another text. The tricky part is filtering the names starting with only F.
View RepliesI'm following a tutorial and I can't work out why the version that I have written is returning null when reading the text file...?
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class AppReadFileFileReader {
public static void main(String[] args) {
File file = new File("test.txt");
BufferedReader br = null;
[Code] ...
I can't see any difference in the code though, and the files being found in order for the null to appear... :?
the text file is within the Java project, and just has three lines :
line one
line two
line three
That's all it say..... But all my program returns is the work 'null'
I'm doing homework and as far as input, my assignment reads: "Your program must take as input the name of a Java source code file such as the source file containing the source code of this assignment." So my question is, how do i do that without linking the directory directly (i.e. C:/users/...)? I'm using FileReader as shown below...
public static void main(String[] args) throws Exception {
FileReader file = new FileReader (WHAT GOES HERE???);
BufferedReader reader = new BufferedReader(file);
String s = "";
String line = reader.readLine();
[Code] .....
I am trying to write a hashset to a text file. Normally, I have no issues with writing to txt as it is simple for me. However, in this case I am absolutely clueless.
A bit of background about the class: it is a hashset of ComputerScientist objects with 2 fields; name, and field of research (and yes, I know what I put to fill up the HashSet does not count, I was only trying to test to see if I could get this to work).
I know the basic setup to use filewriter to save strings to a txt, but I am getting confused with the HashSet element of it.
import java.util.HashSet;
import java.io.FileWriter;
import java.io.IOException;
/**
* Write a description of class ComputerScientistSet here.
*/
public class ComputerScientistSet {
private HashSet<ComputerScientist> computerScientistSet;
[Code] .....
Ive been trying to implement the Filewriter to my code. What I want is to have the textfield data written to a text field. Im thinking you have to specify the text field you want to have in the filewriter statement,I've done something like this, Ive used the try catch block.
if (source == jBPay) {
System.out.println("Pay");
{
double dOrderTotal = dTotal*1.2;
jTTotal.setText(Double.toString(dOrderTotal));
jTTotal.setHorizontalAlignment(JTextField.CENTER); // align text field centre
jTotal.setText(String.format("%.2f", dTotal)); // set pay text field to 2 decimal place
[code]...
What I want is to have the textfield data written to a text file*Hi all, Ive been trying to implement the Filewriter to my code but I cant figure out what im doing wrong.What I want is to have the file data written to a text field. Im thinking you have to specify the text field you want to have in the filewriter statement.
if (source == jBPay) {
System.out.println("Pay");
{
double dOrderTotal = dTotal*1.2;
[code]...
how do I delete a double comment?
How to write a new file:
import acm.program.*;
import java.io.*;
import java.io.PrintWriter.*;
import acm.util.*;
import javax.swing.*;
public class PrintWriter extends ConsoleProgram {
public void run() {
try {
PrintWriter wr = new PrintWriter( new FileWriter ("hello.txt") ) ;
wr.println("Hello world!");
wr.close();
} catch (IOException er) {
println("File could not be saved.");
}
}
}
(I added the imports at top myself.) However, I am getting compiler errors for the lines: PrintWriter wr = new PrintWriter( new FileWriter ("hello.txt") ) , which says that the constructor PrintWriter( FileWriter ) is undefined, and
wr.close();, which says close() method is undefined.
Pretty sure the only real problem is that PrintWriter is not accepting the FileWriter as constructor, but I don't see why. I have tried this on machine with JRE 1.4 and it worked as expected, creating new file titled "hello.txt", prints line of "Hello world!" in that file, and saves it to the directory I picked in the dialog. But I can't get it to work on this machine that uses Compiler 1.6, Java Runtime v8u25.
I have also tried using just a string in the parameter for PrintWriter, such as PrintWriter wr = new PrintWriter ("hello.txt") , and from what I can tell by reading the java spec for java 8, this should work. [URL] .... But I get error message for that constructor as well.
I am having an issue with using FileWriter to print some text to a text file. In the following code, I am supposed to be able to print the initial attributes and the user changed inputs into a file but all I am getting is the memory locations of the objects I created in one long line.
package project3final;
import java.io.*;
import java.util.*;
public class Project3Final {
static class Instrument {
char [] stringNames = {'E', 'A', 'D', 'G', 'B', 'E'};
private final String instrumentName;
[Code] ....
I am having a bit of difficulty understanding/Using FileWriter. Now by my understanding in the API FileWriter allows to use write at the end of your file, if you have text in there already, correct?
I have a file with people info in it. And I created a GUI which allows people to input that data.
Java Code:
File file = new File("People.txt");
FileWriter fw = new FileWriter(file);
People p = new People(firstName, lastName, email, sex));
fw.append(p);
fw.close() mh_sh_highlight_all('java');
Now, I keep getting an error on the fw.append(p)
Java Code:
The method append(CharSequence) in the type Writer is not applicable for the arguments(People) mh_sh_highlight_all('java');
I am using netbeans to create a hotel booking system, just tessting out code to get the booking information input to a file when the next button is clicked.
File file = new File("file.txt");
try (BufferedWriter br = new BufferedWriter(new FileWriter(file))) {
br.write("################################");
br.newLine();
br.write(" Booking Information");
br.newLine();
br.newLine();;
br.write("First Name: " + TxtName.getText());
} catch (IOException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
Nothing is getting wrote to the file though. Does that code seem right?
I am having an issue with using FileWriter to print some text to a text file. In the following code, I am supposed to be able to print the initial attributes and the user changed inputs into a file but all I am getting is the memory locations of the objects I created in one long line.
package project3final;
import java.io.*;
import java.util.*;
public class Project3Final {
static class Instrument {
char [] stringNames = {'E', 'A', 'D', 'G', 'B', 'E'};
private final String instrumentName;
[Code] .....
I have a few questions relating to I/o files.
1.) Is FileReader class the same as File Class. In my book it uses File class to read data from a file, but one of the members here used FileReader so I was wanting to know if it's identical function or not.
2.) When creating an output file, I will use
PrintWriter outputfile("hello.txt")
i just read a new topic of " appending data to a file," meaning if I want to preserve the old file I would have to use this. From my understanding all this does is prevents the old data from being deleted.
Now, in my code if I type ( "hello.txt",true)this would preserve the old data?
One more thing, what does this even do
[CODE]FileWriter file=new FileWriter; PRINTWRITER output=new PrintWriter(file) [CODE/]