Java Runtime Get Result Output From Prompt / Large File - Process Will Hang
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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Mar 17, 2014
I have printed the result of my program into an output file.
For some reason I can't figure out how to get the file output.txt to actually print.
I've tried printing it like I would normally print a file but it's not working.
Java Code:
final PrintStream console = System.out;
File file = new File("output.txt");
PrintStream out = new PrintStream(new FileOutputStream(file));
System.setOut(out);
System.out.println(collection.toString());
System.setOut(console);
What do I do after this? mh_sh_highlight_all('java');
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Jan 5, 2014
reading a large json file which is really huge and it contains pair of id and URL in a array as shown below.. i need to get this all id and URL from this file in my java code and need to perform operations . how to read such a big file and store the contents in java code to process it further.
{
"Array": [
{
"id": "1test",
"URL": "http://servername/test/1test.html"
},
{
"id": "2test",
"URL": "http://servername/test/2test.html"
}
....................many id and URL in the same Array which makes the file Huge..
]
}
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Jun 6, 2014
I want to do basic input/output using Process class. I basically wish that, I should ask user his name and when user provides his name then I would print "Hello '[name]'"
import java.io.*;
public class ReadAndPrintName
{
static Process p;
[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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Jun 7, 2015
Write a program that prompts the user to input an integer and then outputs both the individual digits of the number and the sum of the digits.
Now I have a code for spacing out the integers, and I have a separate code for adding the digits. But I am not sure how to merge them together. Both of them work independently
Spacing code:
import java.util.*;
public class SumoftheIntegers
{
static Scanner console=new Scanner(System.in);
public static void main(String []args) {
int num1, test, rem;
int counter = 0;
[Code]...
Now the sum of the integers code:
import java.util.Scanner;
public class sum
{
public static void main(String[] args)
{
// Create a Scanner
Scanner input = new Scanner(System.in);
// Enter amount
System.out.print("Enter an integer: ");
int integer = input.nextInt();
[Code]...
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Oct 5, 2014
why the output is not giving the proper result? Is this a semantic error?
public class Programming1Practice {
/* testing out instantiation and object oriented programming */
public static class staticValues {
[Code]....
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Mar 22, 2014
So my assignment is to read these values from an input file which I previously created. The 10 values represent miles traveled and I convert them using some formula my prof gave me to get the total cost, and output both values to an output file.
My programming question is the first number on the input file isnt a mileage value its the number 10, which is the number of values to be processed, which we're supposed to use in order to control a for or while loop which we'll use to process the contents of the input file. How would I create a while or for loop and get it to skip the first value of the input file?
We're not allowed to use arrays for this assignment.
Also here's my code so far, and it says its not being able to find the file, I made sure the file name is exactly as saved, and its saved in the same directory as the java class that i created for this assignment so I don't see what the problem could be?
Here's my the class with the main method
import java.util.*;
import java.io.*;
public class QudratullahMommandi_3_07 {
public static void main (String[]args)
[Code] ....
This is the error message I get
----jGRASP exec: javac -g QudratullahMommandi_3_07.java
QudratullahMommandi_3_07.java:17: error: unreported exception FileNotFoundException; must be caught or declared to be thrown
Scanner input = new Scanner(inputSource);
^
1 error
----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.
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Nov 4, 2014
I created a main class called X and two Y and Z classes.
Y and Z implements Runnable classes.
class X contains a static array A that can be accessed in Y and Z.
The Run () method of the class Y reads an input file and populates the vector A.
The Run () method of the Z class uses data stored into the vector A to process some data.
The objective of using threads in this problem is: as the vector A is filled in the Run () method of class Y, the Run () method of the class Z will processing the received values in the vector A.
to do this I did the following calls in the main method of class X:
ObjectY y = new Y ();
Thready thread = new Thread (objectY);
threadY.start ();
ObjectZ new Z = Z ();
Threadz thread = new Thread (objectZ);
threadZ.start ();
is that correct? I'm getting the expected results, but dont know if the code is parallelized in fact.
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Apr 16, 2015
I am working on a management gui for a program. I have implemented the start server button. But now I need to get something working so that when I press stop server the javaw.exe process which is running the the other jar file is stopped and ended.
The gui is going to be using a javaw.exe as well and I don't want to end the entire thing.
I just want to end the javaw.exe process that is running the other jar file.
This is my code for starting it:
JButton btnNewButton_2 = new JButton("Start Server");
btnNewButton_2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Runtime rt = Runtime.getRuntime();
try {
Process pr = rt.exec("java -jar DEDServer_release.jar");
[Code] ....
I just need to figure out what to do to stop it now.
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Jun 15, 2014
I'm working on an assignment where the program has to process a file and read every line then print it out in all caps. I'm pretty sure I have most of it written out, however, I am having trouble with my main method. I am supposed to call my go method in my FileProcessor class and have it use the StringProcessor interface to call my Upper class. I'm using an interface because I will be adding other classes later, but for now I am having trouble with implementing it all in my Driver class.
How do I declare a StringProcessor object in my Driver class and how can I use it so that it would create the file in all caps?
Here's my code so far:
Driver.java
import java.util.Scanner;
import java.io.FileNotFoundException;
import javax.swing.JFileChooser;
import java.io.File;
[Code].....
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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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Oct 14, 2014
I am having some issues with this code its a a DB generator that creates tables and populates them. There seems to be no compiler errors, but there is a runtime error. I have added the error and the code below :
Runtime error:
Exception in thread "main" java.sql.SQLException: [Microsoft][ODBC Driver Manager]
Data source name not found and no default driver specified
at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6964)
[Code] .....
My Code:
MakeDB.java
import java.sql.*;
import java.io.*;
public class MakeDB {
public static void main(String[]args) throws Exception {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
[Code] .....
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Mar 5, 2014
I currently finding a way how can i package a required/dependency JAR with my runnable JAR only using a command prompt like :
how the ECLIPSE IDE export RUNNABLE JAR
I am running on a linux environment, is there a way to do this.
I can only make Runnable Jar without the required JAR by using this command
jar cvfm Test.jar manifest.txt package/*.class
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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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Nov 25, 2013
Our client has a user facing web application running on Jboss. There is a separate admin application (in its own ear) but deployed on same Jboss server on which user facing web application is running.
They need a screen to upload large amount of data into database. Their original files were in excel with size > 60 mb. We suggested following to them:
a. Change upload format to CSV - this brought down file sizes to 25-30 mb
b. Upload process will be MDB - asynchronous processing of data so that admin web app does not stop responding
We also suggested following to them:
a. Host admin app on a different machine so that user facing site does not respond slow during data processing
b. We can provide incremental upload feature and they should upload files in the chunks of 4-5 mb, specifically if they have user a web page to upload such files - they don't buy this argument though.
c. Data processing can be a separate script instead of a part of admin web application. They can FTP files to a designated location and this script will process those files.
I have following questions:
Q1 - Have you seen upload of such large datafiles to a web application? I see sites like Zoho CRM or Salesforce do not support such data imports and mostly fail or not respond.
Q2 - Is there a set of guidelines/best practices to upload large data files of this nature? How do insurance companies or others with enormous set of data accomplish such tasks (what is the architecture of such programs)?
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Apr 7, 2015
I need to built a file upload service which should be memory effective. I should avoid loading the entire file into memory,Since I may have multiple http request which will pile up the Heap memory. Any effective way to upload a large file(For ex:1GB file) using http Streaming. I need to do the file upload on a single http call. Let's consider a scenario where 1 GB file to be uploaded using 512MB Heap memory. Not Sure If practically I can achieve this or not.
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Apr 16, 2015
I am making a ui in which i have a JTextfield and a JButton(run). I am reading values to JTextField from text file and on pressing Jbutton a Batch file runs. Now when i press the Jbutton the batch file runs showing number running, in place of number running, i want to display the JTextfield value. So i want in place of number running it should display JTextfield value running. How can i achieve it.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import java.util.*;
import java.awt.event.*;
[Code] .....
a.text: 1248
p.bat:
echo number running
pause
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Sep 3, 2009
I have a requirement where a large file (100 -200MB) is uploaded from the client to a content management system. I am using a servlet with Apache Commons File Upload API. Apache FileUpload has 2 ways of handling files,
1) Non-Streaming
2) Streaming
Currently I use the Non-Streaming approach where the servlet stores the file in a temp location and upload the same into the content management system - This is taking lot of time so I am trying to implement Streaming API.
Content Management API supports streaming in 2 methods,
a) SetContent - Takes the file's ByteArrayOutputStream as input -> This gives OutOfMemoryException because the file being large
b) AppendContent - Takes the file's ByteArrayOutputStream as input -> This method can be called multiple times to upload the large file but I dont know how to do this. The Apache File Upload gives InputStream of the file and I need to split that into chuncks and append into the content management system.
How to convert InputStream to 4KB ByteArrayOutputStream so that I can use the AppendContent method in content management API?
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Jul 28, 2014
I'm just starting out with learning how to process/parse XML data in Java, following online code/tutorials. I am currently only printing out "catalog."
XML File that I'm trying to read: URL...
import java.io.*;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
[code]...
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Aug 22, 2014
Is there a way to have global variable in Java associated to a process ?
I'm coming from PL/SQL world, I'm looking for something like package variables.
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Mar 3, 2014
I would like to use java se api names like, undo, redo, stylededitorkit, htmleditorkit in editorpane swing. So, I don't understand how to use these apis.
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Sep 7, 2014
I need to kill or remove windows system process like cmd.exe from java code. Like removing it from end process in task mgr. I tried below code but its not removed. Is there a better way we can do this.
killing a system process from java code will create any issues?
public static void main(String[] args) throws Exception { String[] cmd = { "cmd.exe" };
Process p = Runtime.getRuntime().exec(cmd); p.destroy(); }
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Apr 17, 2014
I've got a nasty nullpointer that I have tried to resolve to no avail as of yet. The program should prompt for a listings.txt file and take its info and write to a report file. Here's the stacktrace:
run:
Input file: listings
Exception in thread "main" java.lang.NullPointerException
at java.io.Writer.<init>(Writer.java:88)
at java.io.PrintWriter.<init>(PrintWriter.java:113)
at java.io.PrintWriter.<init>(PrintWriter.java:100)
at kettask2b.PropertyListingsReport.main(PropertyListingsReport.java:34)
Java Result: 1
Some adjustments that I have attempted are:
BufferedWriter pwfo = null;
for (int i = 0; i < args.length; i++) {
String string = args[i];
pwfo = null;
[Code] ....
Here's the code:
package kettask2b;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
[Code] ....
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Feb 18, 2014
I have a large text file of 1 GB size. I need to print the line when a matching word is found in a particular line. Below is the code I am using. But if there are many lines that has the matching word, it's taking lot of time. Any solution to print the lines much faster.
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if(line.contains("xyz")) {
System.out.println(line);
}
}
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Feb 14, 2014
I am looking for a way to compile Java Source-Files at runtime and save them all in an executable jar; almost like an IDE would do. I know that there is the javax.tools package which provides a JavaCompiler interface and you can use ToolProvider.getSystemJavaCompiler() to get an instance of a compiler. However, this method has one important problem: it only works on machines that have the JDK installed. Not when only the JRE is installed.
I guess at this point that I need some kind of third party library that offers an implementation of a JavaCompiler. Unfortunately, this is really complicated to search for on the internet since all top listings when searching "compile java at runtime jre" do not really provide a solution to the problem.
I am writing a (somewhat) complex simulation software right now which is supposed to be used by people who have absolutely no knowledge of programming. At the same time, this software should provide the user with a certain amount of flexibility and control over the flow of the simulation.
My previous take on this problem was to build a complex system to interprete user settings from a GUI. I would basically read the GUI input, output it to some kind of own scripting syntax which I just quickly made up and have that interpreted at runtime. Then I realized, that is a silly concept and I threw it out before I got far into the developement.
The much better solution I came up with is taking the input from the GUI, create java source code from it and compile it at run-time. Seems much cleaner and nicer to me; will also probably have a better performance, but thats not really an issue anyways.
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