Java Discussion Boards

Re: How to convert 2d array into 1d array in java

Member 1278579115-Oct-16 6:06

15-Oct-16 6:06

Basically i was trying to do bubble sorting in 2d array with logic
first converted 2d array into 1 d array then sort the elements and again converted back that array into 2d array

class Sort1
{
public static void main(String...avg)
{
int a[][]={{1,2,3,7,12},{4,5},{7,2,6,9,9,11,22,33,44,55}};
//System.out.print(a.length);
int totalelements=0;
for(int x=0;x<a.length;x++)
{
for(int y=0;y<a[x].length;y++)
{
totalelements++;
}
}
//System.out.print(totalelements);
System.out.println("\n"+"unsorted 2d array"+"\n");
for(int i=0;i<a.length;i++)
{
for(int j=0;j<a[i].length;j++)
{
System.out.print(a[i][j]+"\t");
}

System.out.println();
}

System.out.println("\n"+"converted 2d array into 1d array"+"\n");
int b[]=new int[totalelements];
//System.out.print(b.length);
int l=b.length;
int c=0;
for(int k=0;k<a.length;k++)
{
for(int m=0;m<a[k].length;m++)
{
b[c]=a[k][m];
System.out.print(b[c] +"\t");
c++;
}
}

for( int i =1; i<=l-1;i++)
{
for(int j=0; j<l-i;j++)
{
if(b[j]>b[j+1])
{
c =b[j];
b[j]=b[j+1];
b[j+1]=c;
}
}
}
int n=0;
for(int i=0 ; i<a.length ; i++)
{
for(int j=0 ; j<a[i].length ; j++)
{
a[i][j] = b[n];
n++;
}
}
System.out.println("\n"+"\n"+"Sorted 2d array "+"\n");
for(int i=0 ; i<a.length ; i++)
{
for(int j=0 ; j<a[i].length ; j++)
{
System.out.print(a[i][j]+" ");
}
System.out.println();
}
}
}

Relating Country to its State & Province

Member 1276860030-Sep-16 0:12

Member 12768600

30-Sep-16 0:12

Hi!

I am currently coding in JSF, but using Java for the back-end beans. Was wondering if anyone is familiar to JSF, to help get a solution or an idea on how I could proceed.

So, if I have a database with 2 tables - Country & State,
but I don't want to have to make a call into the database in order to reduce the resources used. How would I implement in the Java bean a connection between the country and its related states?
Considering that I have the 2 selections in a dropdown menu.

Thanks!

Re: Relating Country to its State & Province

Richard MacCutchan30-Sep-16 0:45

Richard MacCutchan

30-Sep-16 0:45

If you do not want to use the database then you need to hold all the data in Lists inside the code, which may be just as expensive.

Re: Relating Country to its State & Province

Member 1276860030-Sep-16 1:17

Member 12768600

30-Sep-16 1:17

And if I make a call to the database, then I'm probably looking to use a couple of for-loops
to go through both tables in my back bean?

Re: Relating Country to its State & Province

Richard MacCutchan30-Sep-16 1:53

Richard MacCutchan

30-Sep-16 1:53

Yes, probably. It's a trade off, whichever method you use will have a cost. You need to decide which is the better option for your application.

compile error: string is private with powershell

shoysmTP15-Sep-16 1:53

shoysmTP

15-Sep-16 1:53

a very beginner question...
i'm a newbie in programming... just started java and read about packaging... i created i directory called firstproject and put a directory with one class inside of it and a FirstProject source file in the firstproject directory itself.
i made a class in that package directory that has a private string in it and tried to invoke from FirstProject source file but
getting compile error that the string is private...
i tried changing the string into protected or even public but still getting this error...
this is the class src file...

<pre lang="java">
package stickers;
public class Sticker
{
  private String note;

  Sticker(String note)
  {
    this.note = note;
  }

  public void displayNote()
  {
    System.out.println(note);
  }
}

this is the FirstProject src file...

Java

package firstproject;
import stickers.Sticker;
public class FirstProject
{
  public static void main(String[] args)
  {
    Sticker sticker = new Sticker("hello sticky mehdi");
    sticker.displayNote();
  }
}

this is the actuall error:
error: Sticker(String) is not public in Sticker; cannot be accessed from outside package

Re: compile error: string is private with powershell

Richard MacCutchan15-Sep-16 2:40

Richard MacCutchan

15-Sep-16 2:40

You need to make your constructor public so other packages can access it:

Java

public class Sticker
{
  private String note;
 
  public Sticker(String note)
  {
    this.note = note;
  }
// ... etc

I would recommend going to The Java Tutorials[^] and working through them.

Load C++ Library Only Once

Django_Untaken10-Sep-16 10:30

Django_Untaken

10-Sep-16 10:30

Hello there. I have managed to load and use c++ dll using JNI, in my java servlet (System.load). It works perfectly on first request I submit. But on subsequent requests, I get this weir d exception.

java.lang.UnsatisfiedLinkError: Native Library WEB-INF/lib/XXXXXX.dll already loaded in another classloader<br />
        at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1525)

Here is my loading code

public void init(ServletConfig config) throws ServletException 
{
    super.init(config);
    ServletContext context = getServletContext();
    String sMathDllpath = context.getInitParameter("MathDLLPath");	
    System.load(sMathDllpath);

}

I studied this tomcat wiki link and implemented their solution, among others, but could not succeed.
How do I implement it successfully? Thnks for anything you share.

Re: Load C++ Library Only Once

Richard MacCutchan10-Sep-16 21:42

Richard MacCutchan

10-Sep-16 21:42

You should declare it as a static action at class level like:

Java

class ... {
    static
    {
        System.loadLibrary("MathDLLPath");
    }
// remainder of your class
}

That will ensure it is loaded when the class is first instantiated, but will only be loaded once.

Re: Load C++ Library Only Once

Django_Untaken11-Sep-16 5:58

Django_Untaken

11-Sep-16 5:58

Richard MacCutchan wrote:
You should declare it as a static action at class level like:

I tried this just now. This is what I have

public class MainServlet extends HttpServlet
{
    static{
	System.loadLibrary("MathDll");
   }

   ......... // rest of the class below this
}

And this is the exception I am getting

<br />
java.lang.UnsatisfiedLinkError: Native Library C:\Program Files\Java\jdk1.7.0_71\bin\MathDll.dll already loaded in another classloader<br />

What am I doing wrong now?

Re: Load C++ Library Only Once

Richard MacCutchan11-Sep-16 7:17

Richard MacCutchan

11-Sep-16 7:17

No idea, but it looks like you may have more than one call somewhere. Time to get the debugger out. Although, I have never used JNI in a servlet so it may be that there is something else happening.

I'm having some issues with a source code

DarkoJava2-Sep-16 16:55

DarkoJava

2-Sep-16 16:55

Hello, I wanted to create a launcher for a game (Minecraft), but then I had an idea, that if I read some source codes that it would make it easier for me to make it, so I went searching for a source code , and I found one, but then I was testing it if it's working or not, and it opened, but then when I pressed launch after seconds it says that it couldn't update or something, I'm gonna put the source code file if you could please help me I'll appreciate that.
SKMCLauncher-fourth[^]
The error is

The following information can be provided to the developer:

com.sk89q.skmcl.LauncherException: Something went wrong while trying to update.
	at com.sk89q.skmcl.launch.LaunchWorker.update(LaunchWorker.java:105)
	at com.sk89q.skmcl.launch.LaunchWorker.call(LaunchWorker.java:141)
	at com.sk89q.skmcl.launch.LaunchWorker.call(LaunchWorker.java:44)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "downloads" (Class com.sk89q.skmcl.minecraft.model.Library), not marked as ignorable
 at [Source: java.io.StringReader@6738ae66; line: 21, column: 27] (through reference chain: com.sk89q.skmcl.minecraft.model.ReleaseManifest["libraries"]->com.sk89q.skmcl.minecraft.model.Library["downloads"])
	at org.codehaus.jackson.map.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:53)
	at org.codehaus.jackson.map.deser.StdDeserializationContext.unknownFieldException(StdDeserializationContext.java:267)
	at org.codehaus.jackson.map.deser.std.StdDeserializer.reportUnknownProperty(StdDeserializer.java:673)
	at org.codehaus.jackson.map.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:659)
	at org.codehaus.jackson.map.deser.BeanDeserializer.handleUnknownProperty(BeanDeserializer.java:1365)
	at org.codehaus.jackson.map.deser.BeanDeserializer._handleUnknown(BeanDeserializer.java:725)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:703)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
	at org.codehaus.jackson.map.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:217)
	at org.codehaus.jackson.map.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:194)
	at org.codehaus.jackson.map.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:30)
	at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:299)
	at org.codehaus.jackson.map.deser.SettableBeanProperty$MethodProperty.deserializeAndSet(SettableBeanProperty.java:414)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:697)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
	at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2732)
	at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1863)
	at com.sk89q.skmcl.util.HttpRequest$BufferedResponse.asJson(HttpRequest.java:470)
	at com.sk89q.skmcl.minecraft.MinecraftUpdater.installGame(MinecraftUpdater.java:166)
	at com.sk89q.skmcl.minecraft.MinecraftUpdater.call(MinecraftUpdater.java:129)
	at com.sk89q.skmcl.minecraft.MinecraftUpdater.call(MinecraftUpdater.java:53)
	at com.sk89q.skmcl.launch.LaunchWorker.update(LaunchWorker.java:101)
	... 6 more

Java sector best?

Member 127154721-Sep-16 7:42

Member 12715472

1-Sep-16 7:42

Which area of Java has the greatest potential? Java security, web/mobile, telecommunications or data analytics?

Java sector best?

Member 127154721-Sep-16 7:42

Member 12715472

1-Sep-16 7:42

Which area of Java has the greatest potential? Java security, web/mobile, telecommunications or data analytics?

Re: Java sector best?

NotPolitcallyCorrect1-Sep-16 8:10

NotPolitcallyCorrect

1-Sep-16 8:10

None of us can foretell the future.

Re: Java sector best?

ZurdoDev12-Oct-16 2:08

ZurdoDev

12-Oct-16 2:08

Security in any field will always be big, in my opinion.

There are only 10 types of people in the world, those who understand binary and those who don't.

Exposing API VS Stored procedure

Java Lead31-Aug-16 5:28

Java Lead

31-Aug-16 5:28

Hi,

I have a Oracle DB in which all the information is stored and this information is been consumed by different teams and below is the two options i have to decide on :

1. Write a Stored procedure and give the stored procedure to the respective teams and they can call the stored procedure.
2. Write a stored procedure wrap it as an API and expose the API, different team will call the API exposed and API will in turn hit the SP and return the response to the team.

Like to know what is the PRON and CRONS with these options and what is the best possible solution to go with.

Thanks

Re: Exposing API VS Stored procedure

Richard MacCutchan31-Aug-16 5:43

Richard MacCutchan

31-Aug-16 5:43

This is nothing to do with Java, nor Service exposed as a API Service VS Exposing as an stored procedure - Design and Architecture Discussion Boards[^].

Can not Access RequestAttribute in JSTL

AmbiguousName26-Aug-16 1:46

AmbiguousName

26-Aug-16 1:46

Hello there. I am trying to get rid of scriptlets. I attach an object from servlet and try to access it in JSTL. But the logs say that JSP can not find the properties of this object. Here is the servlet sample

request.setAttribute("student", student);

Here is the JSTL sample, with different combinations - all producing no result at all (how ever scriptlets do)

// scriptlets work fine - I just want to use JSTL for this
<c:set var="student" value='${requestScope.student}' scope="request" />
<input type='text' value='${student.FirstName}' /> // without single quotes
<input type='text' value='${student.FirstName}' /> // with single quotes

<input type='text' value='<c:out value='${student.FirstName}' />' /> // using <c:out> - with single quotes
<input type='text' value=<c:out value='${student.FirstName}' /> /> // using <c:out> - without single quotes

As you can see, I have tried different combinations but could not get and display value of request attribute using JSTL. What is wrong? Thanks for any input.

This world is going to explode due to international politics, SOON.

Re: Can not Access RequestAttribute in JSTL

rah_sin30-Aug-16 21:07

rah_sin

30-Aug-16 21:07

May be this article can be useful The JSTL Expression Language | Expression Language Overview | InformIT[^]

rahul

[SOLVED] 'TYPE' Cannot Be Resolved To a Type in JSP

Django_Untaken24-Aug-16 3:34

Django_Untaken

24-Aug-16 3:34

It is solved. Class was in default package. I put it in a package and import that Package.Class in JSP. works like a charm.

================
Hello there. I am attaching two variables with a HttpServletRequest request, an integer and an arraylist. After this when I forward request to a JSP, these casting issues arise. Here is the java servlet code

ArrayList<Employee> list_employees = m_objDbLayer.GetEmployeesAll();
int employee_count = list_employees.size();

request.setAttribute("employee_count", employee_count);
request.setAttribute("list_employees", list_employees);

RequestDispatcher dispatcher = request.getRequestDispatcher("/ViewEmployeesPage.jsp");

dispatcher.forward(request, response);

And here is the JSP code where I access these variables

<%@page import="java.util.ArrayList"%>
<%@page import="/WEB-INF/classes/Employee" %>

<!-- all the starting HTML tags here-->

<%
int employee_count= (int)request.getAttribute("employee_count");
out.println("Total Employees: " + employee_count);

ArrayList<Employee> list_users =new ArrayList<Employee>();
list_users = (ArrayList<Employee>)request.getAttribute("list_employees");
%>

I get these exceptions in server log

<br />
1- Cannot cast from Object to int<br />
2- Employee cannot be resolved to a type<br />

As you can see I am importing Employee class in JSP, what is wrong? Why it can not resolve Employee and convert from object to int? Thanks for any input.

modified 26-Aug-16 6:32am.

Drools : Exception in thread "main" java.lang.RuntimeException: Query 'results' does not exist

coolSol23-Aug-16 19:37

coolSol

23-Aug-16 19:37

Hi All,

I am getting exception as Query result does not exist after calling the mehod QueryResults in drools.

qResults = kSession.getQueryResults ("results");

Is there any drools expert on coderanch who can help me to resolve the exception.

Please let me know if you need additional information.

Thanks,

Re: Drools : Exception in thread "main" java.lang.RuntimeException: Query 'results' does not exist

Richard MacCutchan23-Aug-16 22:02

Richard MacCutchan

23-Aug-16 22:02

The message is telling you what the problem is. The query named "results" cannot be found. Check your system settings, configuration etc, or wherever the queries are stored. See also https://docs.jboss.org/jbpm/v5.1/javadocs/org/drools/runtime/rule/WorkingMemory.html#getQueryResults(java.lang.String, java.lang.Object...).

console output to a text file

Member 1142765722-Aug-16 4:55

Member 11427657

22-Aug-16 4:55

i had wrote a code to connect to remote oracle data & execute query to find a task whether to check running or not...

I am getting the output in the console, but i need to print the console output to a file..
eg:
while(re.next){
executeing the query(select * from product_inventory_task)

acutally code connects to mutiple server & get the result.

while printing the result to text file ,it prints only the last value stored query reslut

Re: console output to a text file

Richard MacCutchan22-Aug-16 5:28

Richard MacCutchan

22-Aug-16 5:28

Member 11427657 wrote:
while printing the result to text file ,it prints only the last value stored query reslut

So there is obviously a bug in your code. But since we cannot see your code we have no idea what that bug may be. I already gave you a suggestion to your previous post on this issue, at Re: how to write the console output to text file? - Java Discussion Boards[^]. Did you follow the link I provided?

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