Write Hashset To Txt Using Filewriter
Mar 23, 2015
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] .....
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Jul 12, 2014
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.
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Apr 27, 2014
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?
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Oct 24, 2014
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.
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Dec 10, 2014
A file has the data of the subjects and name of professors. The file contains line for each subject. The line starts with professor Name followed by the Subject name.
Harry Williams Advanced DBMS
James H Computer Networks
Sasha Ben Artificial Intelligence
Harry Williams Software Engineering
Palbo Kastro Formal Languages
Alex W Advanced SE
James H Operating System
Harry Williams Theoretical Foundation
Write a program with setter getter method to read the file, and then write a class to store several professors in a hashset (Single Key and Multiple Values).The program should be able to display all the professors in the set and allow the user to search for a professor.
Input:
Professor Name: James H.
Then the Output will be:
Subjects Taken by the professor: Computer Networks, Operating System.Display No Classes available if the professor name does not exists .
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Oct 10, 2014
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] ....
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Jun 7, 2014
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');
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Nov 18, 2014
Having trouble adding Class (Dollar) objects to a HashSet (money), i have done this before with arraylists and i understand that HashSets are different in that they cannot contain duplicates. Currently when this code is compiled i am getting "null" printed when I run the "howFullDatWallet" method.
import java.util.*;
public class Wallet {
private HashSet<Dollar> money;
private int walletSize = 0;
private int walletFiller = 0;
/**
* Constructor for objects of class Pocket
*/
public Pocket(int walletCap)
[code]....
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Apr 20, 2014
I have a HashSet, which I created to prevent duplicates upon output, but of course it's printing duplicates(or else I wouldn't be posting this). The order of my output does not matter, nor the input. The data type is String in the format (x + "," + z), where x and z are integers, creating a collection of coordinate sets. So to prevent the output of duplicates, I'm trying to get rid of the duplicates before they are added to the collection.
I've tried doing a '.equals()' string comparison but what happens is, since my string is added via one variable, it compares itself to itself and if itself equals itself it won't be added to the collection. I really need to keep this as a comparison of a single variable, because creating a key for each value would be sooo ridiculous for this volume of inputs.
So, with that being said, I would like to add one copy of the string, discard the duplicates, and do this thousands of times..
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Mar 12, 2014
What is the difference between HashSet, TreeSet and LinkedHashSet?.One difference between HashSet and TreeSet is that TreeSet is sorted, whereas HashSet is not sorted. I dont know the other differences
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Apr 3, 2015
I'm fairly new to java, and is just building small programs to get the feel for the language. How I can improve this code.
import java.util.Set;
import java.util.HashSet;
import java.util.Arrays;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
enum DateValidator {
DDMMYYYY(0, 2, 4),
MMDDYYYY(2, 0, 4),
YYYYMMDD(6, 4, 0);
[Code] ....
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Apr 2, 2014
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?
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Jan 12, 2015
Is there any way to find how many number of elements are landing in same bucket in HashSet. I know Reflection could be one way but i am not able to design a program for that.
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Sep 23, 2014
I'm not new to java but i'm not able to solve the following issue: I have a class
public class Localizzazioni implements java.io.Serializable {
private <complexType> id;
public getId().......
public setId().....
The complexType is a class defined in the code somewhere. Now I want to access it in another class I have
Set localizzazioni = new HashSet(0);
localizzazioni=opere.getOiLocalizzazioneOperas(); -- this object give an object of tyoe HashSet
for(Object object : localizzazioni) {
object.get......... // i cannot use any method defined in the class Localizzazioni
}
Why I cannot write inside the for object.getId() and using it?? In other word how i can access the element contained in the object?? the object is an iterator of type Localizzazioni . The class Localizzazioni has some method but i cannot use them? why ....
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Oct 10, 2014
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] .....
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Sep 13, 2014
I have two Strings
String TO = "raj@gmail.com;ra@gmail.com;RS@yahoo.com";
String CC= "rajt@in.com;rht@basss.com";
My query is i want to extract domains from above two Strings and Store these domains in HashSet. How could i do this with minimum code and performance wise.
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This is what I used How to Write a Key Listener (The Java Tutorials > Creating a GUI With JFC/Swing > Writing Event Listeners)
Java Code:
import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class myGame extends JComponent {
public int x = 20;
public int y = 20;
[code]....
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package cs320Labs.servlet;
public class Question {
String description;
String answerA;
String answerB;
String answerC;
int correctAnswer;
[Code] ....
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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)
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.DecimalFormat;
import java.io.*;
import java.io.BufferedWriter;
[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.
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Feb 16, 2015
I'm trying to write information into a file using PrintWriter. The program complies correctly but when it get's to the following part of the program, an error is given. "Exception in thread 'main' java.io.FileNotFoundException" What is wrong with it?
System.out.print("Enter the filename:");
filename = kb.nextLine();
PrintWriter outputFile = new PrintWriter(filename);
outputFile.println(balance);
outputFile.print(item1+" "+item1Price);
outputFile.println(" "+item1Quantity);
outputFile.print(item2+" "+item2Price);
outputFile.println(" "+item2Quantity);
outputFile.print(item3+" "+item3Price);
outputFile.println(" "+item3Quantity);
outputFile.close();
System.out.println("Data written to the file.");
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