Servlets :: No Error Shown While Compiling Java File But Also No Output
Jan 22, 2015
I made a web app to test the ServletContextListener in tomcat according to the book head first servlets and jsps and used the code
out.println("test context attributes set by listener<br>");
Dog dog = (Dog) getServletContext().getAttribute("dog");
out.println("Dog's breed is: "+dog.getBreed());
in the listener class.But the output is showing the first line only and the second println() is not showing any output whereas my Dog class compiled successfully and I didn't see any NullPointerException as expected in the book but somehow it seems like the problem is in the 2nd line of code only but I don't know what.
I also tried to add a 4th line at the end with println() only but with a simple text even that is not running but when I put that same line after the 1st line, the output is shown.I am unable to see what has gone wrong in the 2nd line of code.
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May 21, 2015
I am getting a compile error message when I am trying to compile someone else code using Eclipse. The partial code description is below as follows:
public String decrypt(String password) {
try {
// create the key and parameter spec
KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, interactions);
SecretKey key = SecretKeyFactory.getInstance(keyFormat).generateSecret(keySpec);
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, interactions);
[Code] ....
Below is the following error message:
Access restriction: The type 'BASE64Decoder" is not API (restriction on required library '/usr/lib64/jvm/java-1.8.0-openjdk-1.8.0/jre/lib/rd.jar')
How do I troubleshoot it?
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Oct 30, 2014
I am getting an error as follows while trying to compile a java file for servlet:-
"error while writing BeerSelect: WEB-INFclassesBeerSelect.class (Access is denied)
public class BeerSelect extends HttpServlet
^
1 error"
I am using "C:Program FilesApache Software FoundationTomcat 8.0webappsBeerBottlejavac -d WEB-INFclasses BeerSelect.java" to compile the file.
I am using Windows 8.1
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Feb 11, 2015
I am new in java. I executed a java program using eclipse. the program contain two java file. when i try to run it using terminal in Ubuntu. Two files are not linking. it shows error. i am attaching all the data.
It shows the following error
regex2string.java:83: error: cannot find symbol
str = randomstr.nextString(2000);
^
symbol: variable randomstr
location: class regex2string
1 error
[Code] ...
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Jan 23, 2013
I am a beginner want to compile servlet with following path
javac -classpath Program FilesApache Software FoundationTomcat 5.5commonlibservlet-api.jar;classes:.-d classes srccomexamplewebBeerSelect.java
Problem arises as follows:
javac: invalid flag: FilesApache
Usage: javac <options> <source files>
use -help for a list of possible options
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Jan 8, 2014
See code.
import java.util.*;
public class CQ1v1{
public static void main(String args []) {
Scanner in = new Scanner (System.in) ;
String name = "";
System.out.println("Welcome to the Interrogator") ;
[Code] ....
When I compile getting
CQ1v1.java:12: error: cannot find symbol
x = in.nextLine ();
^
symbol: variable x
location: class CQ1v1
CQ1v1.java:21: error: cannot find symbol
[Code] ...
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Oct 18, 2014
I am trying to create an array where each object includes a service description, price, and time in minutes. I have a Service class and a SalonReport class:
import java.util.*;
public class Service
{
public String serviceDescription;
public double servicePrice;
public int timeMinutes;
[Code] ....
When I compile this, I get an error message that says:
SalonReport.java:8: error: constructor Service in class Service cannot be applied to given types;
salonServices[0] = new Service("Cut", 8.00, 15);
^
required: no arguments
found: String,double,int
reason: actual and formal argument lists differ in length
What this error message means and how I can correct it? I am confused because my SalonService() method has (String service, double price, int minutes), and each object is listed in that exact order.
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Nov 7, 2014
When I try to compile the code it says " method determineWinner in class RPS cannot be applied to given types;" I think there is something wrong with the way i called the determineWinner method but i'm not what exactly is wrong.
public class RPS
{
public static void main( String [] args )
{
String result;
String userName = getUserName();
String playerChoice, computerChoice;
[code]....
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Jun 11, 2014
I keep getting this error upon compiling and can't see the problem with it.
The error is on line "45: 15"
/* 37: */ public static EntityDef forID(int i)
/* 38: */ {
/* 39: 10 */ for (int j = 0; j < 20; j++) {
/* 40: 11 */ if (cache[j].type == i) {
/* 41: 12 */ return cache[j];
[Code] .....
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Apr 12, 2015
I have an input text file as file.txt where, it consists of only real values separated with commas, and arranged as rows as columns as mentioned below :
1,2,3,4,5,6,10,5,8,9
1,4,7,8,9,0,6,4,3,2,1
2,4,5,8.1.3.4.6.7.9.0
the number of rows is 100 and the number of columns are 9, that is they are fixed.Above is just an example, the file consists of decimal values.What I require is for each column of values I need to find out it's average or mean, that is in above example,
for 1st column:(1+1+2)/3
for 2nd column(2+4+4)/3
for 3rd column(3+7+5)/3,,,,,,,like this till the last column.
So I need to take the input from the .txt file, calculate the column average of each column and the average of each column must be displayed as output. I have done a bit of coding, but it is giving a run-time error as NullPointerException.I will forward my code as attachment, the reading of file, is done as string in java and then it must be converted to double values, also to read the comma separated input from a file I have used the split().
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Apr 11, 2013
class Test1
{
public static void main(String args[])
{
void show()
{
System.out.print("its working");
}
show();
}
}
When I compile this program i find the error illegal start of expression
^void show
Test1.java5 ';' is expected
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Sep 9, 2014
I am stuck with my application. I have jsp, servlet application with jasper report server. When I run the application through eclipse, everything works perfectly. But When I try to run it in Tomcat (without eclipse) it gives me the "Unable to resolve the class file " error. I tried all the solutions I got through the google, but still I am unable to come over it.
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May 15, 2014
Problem: On the form window, after pressing the button, it doesn't give any error and doesn't give any output. It doesn't reply and i have to stop compiling to exit. Why does the IDE do that, is it about my Java codes or Form Window codes ? ( I have two classes named Lexical.java and window.java. Working with Eclipse)
Details: I am working on a project that makes Lexical and Syntax analiysis of commands written in SQL Language. My form is in the attachment. If will be necessary i'll put my codes too.
Attached image(s)
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Dec 14, 2014
My dynamic web project has a java class that captures a session variable with the following code.
HttpSession LoginSession = request.getSession();
String VAR = LoginSession.getAttribute("myVar").toString(); //This is the row 127
If i test the app in local (Mac + Java 1.8 + Tomcat 8) all works. In my remote cloud server (Ubuntu 14.10 + Java 1.8 + Tomcat 8) all works, except this class, that has this code. I copy the complete error here. Note that the row 127 of the error message is the second row of the previous code; and, if i comment this row with // and assign a fix variable all works. So, the problem is that 127^ row.
14-Dec-2014 08:15:23.923 SEVERE [http-nio-8080-exec-14] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [srvNavigation.SrvPT] in context with path [/myapp] threw exception
java.lang.NullPointerException
at srvNavigation.SrvPT.doGet(SrvPT.java:127)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:618)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
[Code] ....
How can i solve the problem?
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Dec 1, 2014
In my web application i want to upload file to drop-box. I am getting file name from browser.Is it possible to upload file to drop-box with only file name.
Below the drop-box upload code with java.
File inputFile = new File("New Text Document.txt");
System.out.println("inputFile.getAbsoluteFile(): " + inputFile);
FileInputStream inputStream = new FileInputStream(inputFile);
try {
DbxEntry.File uploadedFile = client.uploadFile("/magnum-opus.txt",
DbxWriteMode.add(), inputFile.length(), inputStream);
System.out.println("Uploaded: " + uploadedFile.toString());
} finally {
inputStream.close();
}
In the above code the place New Text Document.txt we have to provide total path of file.
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Feb 27, 2015
So say I write up a program like a dice roll game, which I see on the forums here. It's all written and good to go and when I hit Run it does what I want it to do, no errors..What do I do with those .class and .java files? Do I compile it somehow into an app I can put on the google play store? What is the NEXT STEP after the program is all written?
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Jul 20, 2013
So I am trying to write the output of two different java class files to one txt file while the program runs. The file name is determined before the program is ran, through the command prompt as arguments. How can I get the second class file to edit the same txt file without running into compile errors.
For right now I'm just going to send everything that the second file outputs to a message String variable, so that the Main class outputs to the the text file. I still want to learn how to write to the same text file directly from the second class file.
import java.io.*;
public class Test{
public static void main(String[] args) throws IOException{
int x;
//create a new file internally called doc. But externally labelled the user input
File doc = new File(args[0]);
if (doc.exists()){
[Code] .....
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Aug 13, 2014
I am using java process to start a system command in windows
Runtime r = Runtime.getRuntime();
Process pr = r.exec(cmdString);
I want to get the prompt out put from cmdString = "cmd /c type fileSmallSize"->>>> It is ok the have the content of the file when file is small.
However, for a large file java process will hang and no Exception occurred, what is the problem?
The easiest testing you can try on the logging.properties file in java.
public static String executeCmdAndReturnPromptResult(String cmdString)
throws Exception {
LOGGER.entering(CLASSNAME,
"Entering executeCmdAndReturnPromptResult()", cmdString);
String cmd = cmdString;
[Code] ....
It seemed to me that the bufferSize is limited so that I can only have it less than a default one, how to increase it?
My question now is how to increase the size of buffer in order to read a larger InputStream ?
BufferedInputStream() default size is
private static int defaultCharBufferSize = 8192;
private static int defaultExpectedLineLength = 80;
How to make it larger and working? I tried to increase the defaultCharBufferSize to 500000000 but it did not work!
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Dec 4, 2014
How to upload file to google drive using java. my java code is.
HttpTransport httpTransport = new NetHttpTransport();
JsonFactory jsonFactory = new JacksonFactory();
GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
httpTransport, jsonFactory, CLIENT_ID, CLIENT_SECRET, Arrays.asList(DriveScopes.DRIVE))
.setAccessType("online")
.setApprovalPrompt("auto").build();
[Code] ....
So in that file object(java.io.File fileContent = new java.io.File("document.txt");) asking complete file path. But in file upload we can get only file name not path.
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Jul 26, 2014
iam unable to view my login form using servlet below are my files....
***************************************************************************
LoginServ.java
***************************************************************************
package com.peg.servUserLogin;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
[code]....
i tried ruuning my LoginServ file and i get no error but i also i am not getting any output..(loging page)
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Mar 7, 2015
I am trying to output data but get empty table. What am I doing wrong? Here is my code:
Class Item:
package com.store.util;
public class Item {
private Long id;
private String name;
private String description;
private String category;
private Double price;
[Code]...
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May 8, 2014
i am doing a program that allow user to run and execute java language in this commandline.jsp, a servlet execute.java , jsp called get consoleout put.jsp to direct it to commandline.jsp...however there a compilation errors cos i could only get a line of string, and when i run loop in commandline.jsp it will not have the output. i could only run helloworld in it.therefore i need code that i can run multiple line in it. i suspect its the print stream error in execute.java
<!DOCTYPE html>
<html>
<head>
<title>java interpreter</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
<script src="jquery-linedtextarea.js"></script>
<link href="jquery-linedtextarea.css" type="text/css" rel="stylesheet" />
[code]....
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Aug 2, 2014
i have a run time error that could not find or load the main file java .
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May 6, 2014
i am trying to do a program captures keystroke and mouseclick from user in a textarea and insert the details intoa text file using java. Mainly such as delay between keys, no. of times backspace being pressed, alt tab press and copy paste mouse click.
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Sep 28, 2014
I have this error that keeps coming up any time I select one of my buttons. It actually doesn't hinder the performance of the project, everything works. But I am concerned I missed something and errors are never a good sign.On a slightly different note, I would like to figure out what the best way to format my output would be? I would like it to display as "100.00 F". I have a couple ideas on how to get the F symbol (or other symbol) by inserting something like
String degreesymbol = "F" or whichever it is and then returning that in the output string later. I can't get the decimal formatted correctly and I don't know how to print the degree symbol.Here is the code
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
[code]....
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Aug 6, 2014
When do i get IllegalStateException in servlets.What it means by trying to write to the output stream (response) after the response has been committed by server. What it means by committing response and uncommitting response. cannot i send uncommitted response.
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