Public Type (name) Must Be Defined In Its Own File
Apr 1, 2014
I have a small issue understanding the following error message that Eclipse returns when i try to run the following code:
class Film {
String tytul;
String rodzaj;
int ocena;
void odtworz() {
System.out.println("Odtwarzamy film.");
[Code] .....
The message itself reads: "Exception in thread "main" java.lang.Error: Unresolved compilation problem:
at FilmTester.main(Film.java:13)"
and the following on the line where the problem arises:
What gives? I'm positive i'm missing something obvious but i can figure it out why
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Mar 30, 2014
Why I cannot use 2 public classes like below?
public class Hello {
public static void main(String[] args){
Welcomer welcomer=new Welcomer();
welcomer.sayHello();
[Code] ....
Exception in thread "main" java.lang.Error: Unresolved compilation problem:
The public type Welcomer must be defined in its own file
at Welcomer.<init>(Hello.java:9)
at Hello.main(Hello.java:5)
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Oct 13, 2014
I am having a little trouble with a part of my Java assignment that needs to have linked lists in it.
I need to write a public method that takes an array of type object to load strings into a linked list.
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Feb 8, 2014
The compiler won't let me declare more than one class as "public". Am i correct in understanding that this is a java restriction ? This means i need to create a new file, for each public class that i want in a package ? The rest of the classes without access modifier will all be package-private. (Q has been asked before probably, but my search could not be narrowed).
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Oct 20, 2014
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:
Java Code: javac NonpublicClass_different_name.java mh_sh_highlight_all('java');
Then a proper class file is generated with the class name, that is NonpublicClass.class, and afterwards I can compile the main program in Start.java.
So the question is what am I missing regarding the cited quote that reads:
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.
? Because adding such an import to CompanyClass.java:
import com.work.company.NonpublicClass;
didn't work either...
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Jan 10, 2015
I'm using a PrimeFaces UploadedFile xhtml page to select a csv file to read and write using a managed bean (SuperCSVParser.java). The file is read and written to an entity class which then persists the data to a database. The application works fine if I specify a file path on the physical server and select a csv file on that file path. But for the production version I want the user to select ANY file name from ANY directory on their local system.
I know about the FacesContext methods and I've looked at some methods from the java.io File class. Most of these methods are about getting the path from the server, where I want to 'pass' the path String from the client machine to allow the uploaded file to go through. When I try with the below code I get:
java.io.FileNotFoundException: data.csv (The system cannot find the file specified)
I'd like to know what I'm doing as I prefer not to explicitly declare a path in the final app. I'm almost sure that's possible.
<h:form enctype="multipart/form-data">
<p:fileUpload value="#{SuperCsvParser.file}"
mode="simple"
auto="true"
[Code].....
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Dec 4, 2014
I'm trying to parse and compare the content of a zip file. However I'm stuck at what SHOULD be a very simple problem, however I can't seem to find a solution. I have done the following:
ZipInputStream zin1 = new ZipInputStream(fin);
ZipEntry ze1 = null;
fin2 = new FileInputStream(fileName2);
ZipInputStream zin2 = new ZipInputStream(fin2);
ZipEntry ze2 = null;
//fin.close();
ze1 = zin1.getNextEntry();
ze2 = zin2.getNextEntry();
Which gives me the first entry of each zipfile as a ZipEntry type object. I have tried getting the path of the file (inside the zip file) and using this to create a File type object. This does not seem to work though I get:
Exception in thread "main" java.io.FileNotFoundException: My DocumentsmetadatacoreProperties.xml (The system cannot find the file specified)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(Unknown Source)
at java.io.FileReader.<init>(Unknown Source)
And this is because I get a null return from trying to create the File file1 = new File(correctLocation);
I guess I cannot access the file inside a zip file this way. So my question is how can I make a ZipEntry type object into a File type object?
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May 21, 2014
String contentType = fi.getContentType(); gives text/plain when my file is.txt file and gives image/jpeg when my file is .jpeg file but when my file is .jar or .docx it will return application/octet-stream and application/vnd.openxmlformats-officedocument.wordprocessingml.document respictively so what to do to get exact mime type.
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Oct 27, 2014
Is there a way of detecting the file's type (whether it is a pdf, jpg, png,or anything else) by reading the content of the file. We could read the extension of file to determine it's type, but then extensions can be forged too. So I would like to know if the content inside a file is of a particular type or not. I'm not sure about this, but I have heard somewhere about each having having a specific kind of header which determines its type. So is it possible to read that header and determine it using a program?
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Feb 17, 2015
I'm a independent IT contractor. On 2 systems this week I've experienced an issue when attempting to download JAVA the file is of an unknown type in IE. See attached. Alternative browsers on the same machine function properly.
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Dec 27, 2014
I want to create a program where I need to create an object of list type such as text file will contain nos like 1,2,3,4,5 and write into text file and delete the in FIFO order i.e 1,2,3,4,5...how i can achieve to write a program? I tried bt everytime got concurrent modification exception or Array out of bound exception.
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Mar 17, 2015
public class InputFileData {
/**
* @param inputFile a file giving the data for an electronic
* equipment supplier’s product range
* @return an array of product details
* @throws IOException
*/
public static Product [] readProductDataFile(File inputFile)
throws IOException{
// YOUR CODE HERE
}
This code is meant to be used to read a text file and store the data in an array of type Product[]. I know how to read in a text file and have it sort it into an array, but I've never seen code laid out in this fashion before (specifically "public static Product[]", and I'm unsure how to work with "(File inputfile)". I've looked all over the place but can't find any examples of anything like this.
Also, the code given cannot be changed, as it's that code I have to work with.
I still don't understand how to use it as a whole. For example, do I read the file in the main and have this method read that in and output to the Product class? Do I read the file in this method? I can't work out how to make this work when I have to use this method.
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Sep 18, 2014
If I specify the directory in file type or path string type how can I get a list of files that are file type .yml in that folder, so I can loop through and do something with each single file.yml in that specified directory.
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Jan 12, 2015
This issue is regarding response from the servlet
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.
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Apr 14, 2015
I am simulating a game. This involves creating two Player objects(either HumanPlayer or ComputerPlayer), a TheBoard object, a TheGame object and a TheGameManager object. In the TheGameManager, i am trying to get it so that i can save the two Player objects, the TheBoard object and the TheGame object in current use at some point in the game and then load them later at some point. However, after debugged, i have found that it doesnt like the writeObject() method and skips and sends an exception up.
My TheGameManager class has the following fields:
public class TheGameManager implements GameManager {
private Player player1;
private Player player2;
private TheBoard currentBoard;
private TheGame currentGame;
//private String[] args;
private int iterations = 1;
[Code] .....
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May 2, 2014
I have Spring/CXF project in RAD. I have the following problem message:The servlet mapping "XXX" refers to a servlet that is not defined.
<servlet>
<servlet-name>XXX</servlet-name>
<display-name>XXX</display-name>
<servlet-class>org.apache.cxf.transport.servlet.CXFServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>XXX</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
However, The servlet was defined in the web.xml file.I searched the internet and tried a few things but to no avail.
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Mar 11, 2014
Below code I am using to typecast int to char.
char escapeValue = (char)0;
char cha = (char) 10;
escapeValue = (char)(escapeValue * cha); // Here am getting the above error.
I have 38 similar issues in my workspace.
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Apr 30, 2014
If you have final int i = 1;
short s = 1;
switch(s) {
case i: System.out.println(i);
}
it runs fine. Note that the switch expression is of type short (2 bytes) and the case constant is of type int (4 bytes).My question is: Is the type irrelevant as long as the value is within the boundaries of the type of the switch expression?I have the feeling that this is true since:
byte b = 127;
final int i = 127;
switch(b) {
case i: System.out.println(i);
}
This runs fine again, but if I change the literal assigned to i to 128, which is out of range for type byte, then the compiler complains.Is it true that in the first example the short variable and in the second example the byte variable (the switch expressions) are first implicitly converted to an int and then compared with the case constants?
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Aug 14, 2014
class Passenger{
String name;
int age;
char gender;
int weight;
public Passenger(){
[Code] ....
This is showing error.....error it gives isthat it cannot change from string type to passenger type......... How to do it??????
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Apr 22, 2014
Got a problem with generics, which I'm still pretty new at. Here's a program that compiles fine:
import java.util.ArrayList;
import javax.swing.JComponent;
public class Experiments {
public static void main(String[] args) {
ListHolder holder = new ListHolder();
[Code] ....
It's useless, but it compiles. If I change Line 14, however, to add a generic type parameter to the ListHolder class, Line 10 no longer compiles:
import java.util.ArrayList;
import javax.swing.JComponent;
public class Experiments {
public static void main(String[] args) {
ListHolder holder = new ListHolder();
[Code] ....
I get this error:
Uncompilable source code - incompatible types: java.lang.Object cannot be converted to javax.swing.JComponent
at experiments.Experiments.main(Experiments.java:10)
Apparently, the introduction of the type parameter leaves the compiler thinking that aList is of type Object. I can cast it, like this:
JComponent c = ((ArrayList<JComponent>)holder.aList).iterator().next();
That makes the compiler happy, but why is it necessary? How does adding the (unused) type parameter to the ListHolder class end up making the compiler think the aList member of an instance of ListHolder is of type Object?
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May 23, 2015
I am trying to create a simple programme that adds two defined matrices together,
public class Question4 {
int [][] numeros1 = { {1,2,3},
{4,5,6}
};
int [][] numeros2 = {{2,5,8},
{3,7,9}
[Code] ....
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Feb 13, 2014
In my main method I am trying to create a Timer, but when I put new Timer(1000,listener) the constructor is not defined. It is when there is nothing in it. I find this super weird because in all my other programs this does not happen. I looked at the documentation and can't see what I am doing wrong, so I turn here.
ActionClass Java Code: import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.*;
public class Action extends JComponent {
[Code] .....
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Mar 22, 2015
I have a String repersentaion of some Object.I want that object convert back into some class type how can I do this?
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Dec 9, 2014
I am trying to understand a question:
R2 (x,y) -- Make the Point class code that implements a corresponding abstraction to a given point in R2. You should explicitly provide the manufacturer's code P (double x, double y) for the Point class. And code for the methods, whose definitions are:
- public double getXCoordinate ();
- public double getYCoordinate ();
- public setXYCoordinates (double x, double y);
- public moveTo (double x, double y);
- public printAtts ();
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Sep 7, 2014
I want to make a program in which i write the Months Strings via while into the checkbox.
I already did that but i have also to add an day if February is a loop day.
So my question is how to say java that if Months is equal to February & year is a leap year, add 1. (i didn't wrote the year code because it's not relevant for my problem.)
Java Code:
public String[] Months ={"January","February","March","April","May", "June", "July", "August", "September", "Oktober", "November", "December"};
public Asg1KeapYear() {
initComponents();
int MonthNo = 0;
[Code] ....
Netbeans shows me .equals() on incompatible types on Months.equals, do i have to declare it somehow?
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Dec 3, 2014
I know that I am not 100% comprehending try/catch blocks, but after scouring message boards, forums, and Oracle, I still can't pick out where I am going wrong.
I have a ValidateInput class where I am trying to check that a String only has letters. If not, then throw an exception message via JOptionPane. I created my own NonLetterException class. When I call the method containing the try/catch Eclipse gives me an Unhandled Exception Type error.
in main()
ValidateInput validate = new ValidateInput();
String name = "error";
for(int x = 0; x < 1;){
name = JOptionPane.showInputDialog("Welcome. What is your name?");
boolean isItName = validate.stringInput(name); //error appears at validate.stringInput
if(isItName)
[code]....
Aren't I handling it in the try/catch? What did I miss?
Also, I have have tried the NonLetterException class as nested in ValidatedInput, but also not nested. To me nested makes more sense. I have never nested classes before, but it makes sense to me because I am not using this exception in other parts of my program.
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