Exists Method Always Read True Even If File Doesn't Exist
Nov 20, 2014
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()){
If I'm checking using an if statement if a file exists like so:
public boolean export(String envName,String fromFile,String toFile) { Vector<String> vector = new Vector<String>(); File file = new File(fromFile); if(file.exists() && file !=null) { return true; } return false;
If it returns true for existing then how would I do another if statement that would say if file returned true then check said file for an id. If Id exists extract all data associated with that id and store in Vector object. Would it be like this:
I'm trying to read a xml file and delete it's contents. I do this by reading the file,writing it to a temp and then overwriting the original with the temp by renaming it
//overwrite original xml file with new file boolean successful = outputFile.renameTo(inputFile); System.out.println("success");
It does say the value of the local variable is not used however. I've debugged to ensure it hits the code it always prints out the line after too.It just does not overwrite my original xml file with the temp one.
It's had votes on stack so I thought that would of been reputableStack - overwrite but the second one got voted as a good answer. But still I would like to know if my code can work or not.
I am just trying to test this array, for a locker combination program that involves classes...but the array is printing out the whacky numbers for the location. When I try to call the method in the main, it does not work. How do I call a method that exist within a class into the main method?
public class locker { public static void main(String[] args) { CombinationLock();
I'm currently working on a java project simply to learn java. So far, it creates a window and makes a properties file, or appends data to it if it already exists. The problem is that I'm not quite sure how to check if the file already exists to append data to it. I'm currently using a boolean (configCreated) that appends data when true, and creates a file when false. The problem is that this boolean is always false since it's at the beginning.
Logic her eis when user selects option1, it asks for user to enter name and as soon as user enters name, it should compar name to existing names in txt file. I have user while loop and for loop but for some reason, it doesnt compare properly as there seems to be some mistake in looping and it just read first line or you can say single line rather than comparing it with all lines in txt file. i have attached votes.txt file with this. Also, if user doesnt exists infile, it will ask user to enter vote as yes or no and add it to file and then count total number of Yes and No votes from file and compare them.
my votes.txt file looks as below with two columns namely (name and vote).
Hiren No samir yes bob no rikul no master yes patrick no summer yes bhanja no
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 am new to Java and would like to ask how to do this question specifically:
Code a Java method that accepts a String array and a String. The method should return true if the string can be found as an element of the array and false otherwise. Test your method by calling it from the main method which supplies its two parameters (no user input required). Use an array initialiser list to initialise the array you pass. Test thoroughly.
This is a college course assignment that consists of classes TotalSales and TotalSalesTest.In the main program I have created a two dimensional array to output a columnar layout with cross-totals in 4 rows and 5 columns. This program outputs sales totals by row for each sales person(1 - 4) and output by column for products(1 - 5). I have created extra elements in the array to store total for rows and columns. So far both classes compiles. The problem is that although the PrintWriter creates a notepad file, it doesn't print to it. I don't seem to understand the input and output methods completely. I finished another program similar to this using basically the same try and catch that read the file and printed out a document in notepad. Here is the code and I'll try include the input file.
import java.util.Scanner; import java.io.*; public class TotalSales { private int salesPerson; //declare class variable private int productNumber;//declare class variable
so i followed a tutorial on youtube called "Java Game Development with Slick" - by thenewboston,URL....okay, so i have made my game / program, and now i just want to export it to a jar file that people can double click and play..unfortunately when i double click the .jar file nothing happens...i get the little "loading" thingy on my courser but it disappears after about 5 seconds and then nothing happens :(the way i made it into a jar file is by doing the following:
-right clicked my java project.. -clicked on "export".. -clicked on java / Runnable JAR file -filled in the stuff, (JARs destination ect..) -pressed finish.. -then i got a jar file on my desktop and double clicked it....but as i said....nothing happens
I have two files - I can get the second one to populate with the first ones data and then delete the first one. I cannot get it to then rename itself to the name of the first file. It also only hits the 'rename' section of the code providing I place system.gc in otherwise it completely skips it.
I compiled the applet, then put the applet in an HTML file using notepad and saved the html file in the right place for it to run correctly. The HTML file runs smoothly, but then it only shows the scrollbar part of my applet, and not the images or any text...
Why is This?????
Java Code:
import java.awt.*; import java.applet.Applet; import java.awt.event.*; import javax.swing.ImageIcon; public class Temperature_Convert extends Applet implements AdjustmentListener { private Image temp; private Scrollbar bar; private int old, newtemp = 0;
I have a question about the following snippet concerning the steps the javac compiler follows to compile a program:
[...]at first, searching a class within a package is discussed if the latter doesn't contain a full package name[...]
It is a compile-time error if more than one class is found. (Classes must be unique, so the order of the import statements doesn't matter.)
The compiler goes one step further. It looks at the source files to see if the source is newer than the class file. If so, the source file is recompiled automatically. Recall that you can import only public classes from other packages. A source file can only contain one public class, and the names of the file and the public class must match. Therefore, the compiler can easily locate source files for public classes.
However, you can import nonpublic classes from the current package. These classes may be defined in source files with different names. If you import a class from the current package, the compiler searches all source files of the current package to see which one defines the class. I don't quite understand the red fragment. I wondered if the word "import" nonpublic classes from the current package weren't a synonym for the word "use", since why would we want to import a class from the same package when compiler searches the current package automatically anyway?
However I wanted to test nonpublic classes that are contained in source file which name doesn't match the class name:
NonpublicClass.java:
Java Code:
package com.work.company; class NonpublicClass { public void description() { System.out.println("Working!"); } } mh_sh_highlight_all('java');
[Code] ....
Everything's fine when the source file names are the same as above. However, when I change NonpublicClass.java to a different name, there's an error "cannot find symbol" in:
Java Code: NonpublicClass v = new NonpublicClass(); mh_sh_highlight_all('java');
I noticed that the class file for NonpublicClass isn't even generated so that's probably the cause. If I change to the directory of the package the NonpublicClass is contained in and compile it directly, i.e. issue for example:
There's loads of problems with this. What I'm trying to do.
1) get a program to add the contents of an array together, preferably with a for loop and not the heavy handed version I've tried to use here.
2) get the for loop's output just once, since it won't compile or recognise the variable outside of the loop. How do I make the loop's 'counter' variable available everywhere?
public class retint { public static void main(String[] args){ int[] onetoTen = {1,2,3,4,5,6,7,8,9,10}; for (int i=0; i<10; i++) { int counter = (onetoTen[0] + onetoTen[1] + onetoTen[2] + onetoTen[3] + onetoTen[4] + onetoTen[5] + onetoTen[6] + onetoTen[7] + onetoTen[8] + onetoTen[9]); System.out.println(counter); } }
Terrible code, I know. There has to be a more efficient way.
I have tried this code to insert into datbase if not exists but i get an Exception in thread "main" com.mysql.jdbc. exceptions.jdbc4. MySQL SyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE NOT EXISTS (SELECT teamName FROM Teams WHERE teamName = teamName) LIMIT 1' at line 1
stmt.executeUpdate("INSERT INTO Teams(teamId,teamName,league) VALUES ("+i+",'"+loser+"','"+league2+"')WHERE NOT EXISTS (SELECT teamId,teamName,league FROM Teams WHERE teamName = teamName) LIMIT 1;");
I need to check the existence of email accounts before sending them mails to avoid going to a blacklist for sending to non real accounts.
I was thinking on (SSL)Sockets and smtp commands but I cant get it to work properly I am shooting in the dark here...
I have a JAVA application that sends mail to the people that buy certain things but the information quality is bad, so I must check if the mail exists before sending the mail....
I am working on a project that requires me to build a database with random access file, representing products, the base product contains a name (about 30 characters), a price (double), and a quantity (integer). I have worked on this project for probably 15+ hours and have tried so many things and feel like I've barley made any progress...
The part i am really struggling with is taking the data from the text file and creating an object array with it using the product class. Once ive accomplished that, i have to use that data to create a random access file with the data.
Here is the base Product class that must be used to create the objects for the array.
public class Product { public String pName; public String stringName; public double price; public int quanity;
[Code] .....
And then here is the data from the text file that i must extract to use to create product objects.
These continue for about 40-50 entries, they are not separated by a blank line though i had to add those so it would display correctly, each entry is on its own line with name separated with spaces, then price after a comma, then quantity after the second comma.....
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.
Well my code is supposed to ask for an input file and then (ex: input.txt), read the input file and create an output.txt file with the anagram for the words in the file. Also it should be displayed on the screen. However my code doesn't display the anagram on screen or the output file!
/* This program will read a file given by the user, read the words within the file and determine anagrams of the given words. If the file that the user inputs is empty, then the program will output "The input file is empty." * The program will read the file line by line, counting the total number of words read. If there are more than 50 words, "There are more than 50 words." * will be printed, and the program will terminate. After each line is read, the words in the line will be separated,punctuation characters will be removed, and upper case characters will be switched to lower case. * If any word is larger than 12 characters, that word will not be considered in the total amount of words in the file and it will not be sorted. * After each word is read, the letters will be sorted and stored into an array containing each * word's 'signature'. After all the words have been read, words will be printed to the output file on the same line based upon their signature. */
public class Anagram { //Creating constants for maximum words in file and maximum chars in word public static final int MAX_CHARS = 12; public static final int MAX_WORDS = 50;
I am trying to create a file browse option in my jsp and later after browsing, all i want to do is to read that file in my jsp without saving it into that database so that i can perform encryption for it and save that encrypted file later into my database. please provide reference link so that i can refer to some applications and and move ahead with my work.
I am trying to make a jar file in intelliJ. My directory that holds all the java classes is C:rafficProjectsrccege. In cege there is a package ui where there is a class GuiMain. And I have imported the GuiMain() in my Main() class.
I have this code lines:
package cege; import cege.ui.GuiMain;
and when I use the terminal in the intelliJ and write the command:
C: rafficProjectsrccege>javac *.java
I get this message:
Main.java:3: error: package cege.ui does not exist
import cege.ui.GuiMain;
but actually, I have already put this line in my code. what could be the problem?
I am trying to write to a file but everything I have tried doesn't seem to work. What I want to do is read a file and then output back to the same file on a new line. The text file contains the sentence "Java is a programming language".
import java.util.Scanner; import java.io.*; class HW1B { public static void main(String[] args) { Scanner fileIn = null; try { fileIn = new Scanner (new FileInputStream("text.txt"));
[Code] ....
These are the errors :
HW1B.java:19: error: no suitable constructor found for Scanner(FileOutputStream) fileOut = new Scanner (new FileOutputStream("text.txt")); ^ constructor Scanner.Scanner(Readable) is not applicable (argument mismatch; FileOutputStream cannot be converted to Readable) constructor Scanner.Scanner(InputStream) is not applicable
[Code] ....
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output 2 errors
I am trying to read a file and input each line of the file into an array. I have not set the array size as I was hoping to fill the array using a while loop. Unfortunately the scope of the array does to work inside the while loop so I am being told that the array 'students' has not been initialised even though it has just outside of the while loop. Is it possible to do what I am trying to without having the array initialised in the while loop as surely the array will be reset every time if it was in the while loop? Here is my code:
public static void students(String file) throws FileNotFoundException { try { File studentInfo = new File(file); Scanner input = new Scanner(studentInfo); String[] students;
I have a small issue with my code where im encrypting and decrypting messages.
My import org.apache.commons.codec.binary.Base64;. does not work.
It says binary does not exist_ Why this happens?. I've downloaded the codec but im starting to wonder if it has to do with where the codec folder is located, but i may be wrong.
