₦airaland Forum

Javanian:
Is the problem reading from the JtextArea, Writing to file or both?

the thing is i want to simply extract text from a text file and store in an array, then
again save those text to another text file, i pretty much got the algorithm(or so i think) but the implementation of the
individual methods seems to be a major headache,


i wrote two methods, one to extract words a single textfile and another to extract words
from many textfiles(up to 2000) , the later seems to work well, but the first keeps throwing a runtimeException
i cant see the bug, so please @javanian @ @allthegurus am all ears (please help out a newbie)

String FileName;
 static int i;
    void getDisplay(String FileName){
    EmailExtract em= new EmailExtract(); //never defined the EMAILEXTRACT OBJECT
                                          //INSIDE THE CONTAINING CLASS TO AVIOD
                     //STACKOVERFLOW ERROR!!!
   
        
      // DoExtract();
try{
  // 
  String FileName_=FileName;
        
        {ReadFile File = new ReadFile("C:/Users/eMachine/Documents/I.txt";
        String [] arylines= File.OpenFile();
        
for ( i=0; i < arylines.length; i++ ) {
assert arylines.length!=0 || arylines!=null: "no words found in specified file! err! #2021";
    String[] emp=arylines[i].split("\\s+";
    
 System.out.println(emp[i]+" //////////";}        
}}
        catch(IOException e){System.out.println(e.getMessage());
        JOptionPane.showMessageDialog(em,"err! #4041    file not found at specified location";
        
        System.out.println("specified file path not found!";
        
        }
 

        }
   

Anagor13: [img]http://2.bp..com/-BGzxp5di3uU/VBWJ3hToSqI/AAAAAAAABdo/p6kBNhq5xTw/s1600/nigerian-alpha-jet%2B.jpg[/img]
A Nigerian air force Alpha Jet with tail number 466 has gone missing from the radar.

Nigerian defense sources said the jet disappeared from the radar around Adamawa state after it went for routine operations on Friday against Islamist militants Boko Haram, who had been on the rampage in the northeastern parts of Nigeria. The jet is the only known functioning jet engaged in operations against the militants.
The Nigerian defense also said it is also looking for two fighter pilots that were operating the jet when it disappeared from the radar. It is not known if militants shot down the jet.

Source: http://naijadebit..com/2014/09/nigeria-jet-used-in-bombing-operations.html

uken73: I currently don't have a Java compatible editor on my system to assist me with syntacs errors but I made some modification on your codes with comments and emphasis on the modifications. I hope this solves your problem.

public class Workers extends javax.swing.JFrame 
{
	ResultSet rs2; //moved here to increase it level of access so that it can be
                           // available in the btnNextActionPerformed event method
	public Workers() {
		initComponents();
		DoConnect();
	}
	void DoConnect( ) {
	Connection cont; //move here to make it available in the catch block for closing
	try{
		String host = "jdbc:derby://localhost:1527/Employees";
		String uName = "admin1";
		String uPass= "admin";
		cont = DriverManager.getConnection( host, uName, uPass); //declaration moved outside try block
		Statement stmtt = cont.createStatement();
		String SQL = "SELECT * FROM Workers";
		rs2 = stmtt.executeQuery(SQL); //declaration moved to class field
		rs2.next( );
		int id_col = rs2.getInt("ID" ) ;
		String first_name = rs2.getString("First_Name" ) ;
		String last_name = rs2.getString("Last_Name" ) ;
		String job = rs2.getString("Job_Title" ) ;
		String id = Integer.toString( id_col ) ;
		textID.setText(id);
		textFirstName.setText(first_name);
		textLastName.setText(last_name);
		textJobTitle.setText(job);
	}
	catch ( SQLException err ) {System.out.println( err.getMessage( ) );	}
	}
	finally{cont.close();}//finally block introduced to handle closing of database connection.

	private void btnNextActionPerformed(java.awt.event.ActionEvent evt) {
		try
		{
                        //rs3 for which I couldn't find it's declaration has been renamed to rs2 
                       //to correspond to rs2 declared as data member
			if( rs2.next()) 
			{ 
				int id_col = rs2.getInt("ID" ) ;
				String first_name = rs2.getString("First_Name" ) ;
				String last_name = rs2.getString("Last_Name" ) ;
				String job = rs2.getString("Job_Title" ) ;
				String id = Integer.toString( id_col) ;
				textID.setText(id);
				textFirstName.setText(first_name);
				textLastName.setText(last_name);
				textJobTitle.setText(job);
			}
			//cont.close(); moved to finally block in DoConnect method.
		}
		catch(SQLException err) {System.out.println(err.getMessage());}
	}
}

Notice that I enclosed the code segment in [code][/code] tags so that it can be formatted well for ease of reading the code.

Javanian: OKAY, Let's start.

First of all, It is imperative for you to know that creating a connection each time a button is clicked is wrong in every way possible. You should put your connection statements in a method and place it in your constructor. So it establishes a connection as soon as the application starts.

So assuming the method is called InitDatbase()

Your code should be something like

void InitDatabase()
{

   try 
   {
        String host="jdbc:derby://localhost:1527/Employees";
        String uName="admin1";
        String uPass="admin";
        connection cont =DriverManager.getConnection(host,uName,uPass);
        Statement stmtt= cont.CreateStatement();
        String SQL="SELECT * FROM Workers";
        ResultSet rs3=stmtt.executeQuery(SQL);
    }
}

Then you call your InitDatabase() in your constructor like this

  public YourClassName
  {
        InitDatabase();
  }

Okay, i don't really know how you intend to make your app work. So i will touch a possible scenario i can think of. I am going to assume that as soon as the app loads it displays the first user in the database. To do this, you should create a method somewhere and probably call it firstUser();

In your first user method, do this.

void firstUser()
{

try
 {
       rs3.first();
       //get value
       string fname=rs3.getString(Fname);
       //set value
       txtFirstName.setText(fname);
 }

}
Now in your btnNextActionPerformed method, do something like this. This would work for the 'NextUserButton'

try
 {
       rs3.next();
       //get value
       string fname=rs3.getString(Fname);
       //set value
       txtFirstName.setText(fname);
 }

Capnd143:

//ok i guess i am starting to be a pain in the ass around here, but i seriously am not getting it,
//i have never been stucked so long in a particular problem, its been 4 days now, i have done virtually everything am
// told but keep getting undesired results, dunno whether its related to my java version or what, so am posting my entire code here
//sturborn code begins here
public class Workers extends javax.swing.JFrame {
public Workers() {
initComponents();
DoConnect();
}
void DoConnect( ) {
try{
String host = "jdbc:derby://localhost:1527/Employees";
String uName = "admin1";
String uPass= "admin";
Connection cont = DriverManager.getConnection( host, uName, uPass);
Statement stmtt = cont.createStatement();
String SQL = "SELECT * FROM Workers";
ResultSet rs2 = stmtt.executeQuery(SQL);
rs2.next( );
int id_col = rs2.getInt("ID";
String first_name = rs2.getString("First_Name";
String last_name = rs2.getString("Last_Name";
String job = rs2.getString("Job_Title";
String id = Integer.toString( id_col );
textID.setText(id);
textFirstName.setText(first_name);
textLastName.setText(last_name);
textJobTitle.setText(job);
}
catch ( SQLException err ) {
System.out.println( err.getMessage( ) );
}
}
// crazy button to handle the database naigation begins here
//=======================================================================================//
private void btnNextActionPerformed(java.awt.event.ActionEvent evt) {
try
{
if( rs3.next()) //for some crazy reason my netbeans underlines my rs3 object variable
//and keeps shouting "cannot find symbol"
{ //when i know so well i declared that variable
int id_col = rs3.getInt("ID";
String first_name = rs3.getString("First_Name";
String last_name = rs3.getString("Last_Name";
String job = rs3.getString("Job_Title";
String id = Integer.toString( id_col );
textID.setText(id);
textFirstName.setText(first_name);
textLastName.setText(last_name);
textJobTitle.setText(job);
}
cont.close();
}
catch(SQLException err) {System.out.println(err.getMessage());}
}

//ok i guess i am starting to be a pain in the ass around here, but i seriously am not getting it,
//i have never been stucked so long in a particular problem, its been 4 days now, i have done virtually everything am
// told but keep getting undesired results, dunno whether its related to my java version or what, so am posting my entire code here



//sturborn code begins here


public class Workers extends javax.swing.JFrame {


  
    public Workers() {
        initComponents();
        DoConnect();
    }
 void DoConnect( ) {
  try{    
       String host = "jdbc:derby://localhost:1527/Employees";
String uName = "admin1";
String uPass= "admin";

        Connection cont = DriverManager.getConnection( host, uName, uPass);
        
        Statement    stmtt = cont.createStatement();
        String SQL = "SELECT * FROM Workers";
        ResultSet rs2 = stmtt.executeQuery(SQL);
       rs2.next( );
int id_col = rs2.getInt("ID";
String first_name = rs2.getString("First_Name";
String last_name = rs2.getString("Last_Name";
String job = rs2.getString("Job_Title";
String id = Integer.toString( id_col );
textID.setText(id);
textFirstName.setText(first_name);
textLastName.setText(last_name);
textJobTitle.setText(job);

       
   }
   
  
catch ( SQLException err ) {
System.out.println( err.getMessage( ) );

}
    }

  // crazy button to handle the database naigation begins here
//=======================================================================================//

 private void btnNextActionPerformed(java.awt.event.ActionEvent evt) {                                                
        
        try
        {
             
        
        
         if( rs3.next())           //for some crazy reason my netbeans underlines my rs3 object variable 
                                      //and keeps shouting "cannot find symbol"
           {                         //when i know so well i declared that variable
int id_col = rs3.getInt("ID";
String first_name = rs3.getString("First_Name";
String last_name = rs3.getString("Last_Name";
String job = rs3.getString("Job_Title";
String id = Integer.toString( id_col );


textID.setText(id);
textFirstName.setText(first_name);
textLastName.setText(last_name);
textJobTitle.setText(job);
         
         }
         
         cont.close();
        }
            
catch(SQLException err)           {System.out.println(err.getMessage());}
    
        
    }                                       

uken73: Yes Null Pointer Exception indicates an attempt to access an uninitialized variable and like Javanian has already said, it's most likely the ResultSet rs. Confirm that it has been initialized.

Javanian: First of all, this is not a logical error, it is a run time error. You are most likely trying to utilize a variable you haven't initialized or a variable that points to null hence the 'NullPointerException'. I can't see the rest of your code but i suspect it is comming from the result set variable 'rs'. Check to see if it has been initialized and if it actually holds any value.

DharkPoet: It aint that much bro!!

asalimpo: Get any telco modem. And update ur software. Write d internet cost as learng expenses. Download ebooks, and software and ide.
Actually,some wud recommend youtube. I wont. Except for installation . Ive never found youtube to b of any help for serious questions.
I dnt know terrible internet speed is over there but where i be at, abuja,it's okay (mtn). Sometimes,it can b poor,but wen it picks up, it gets d download done.
I'm an ultra heavy browser and the 4.5g i get on their night plan doesnt scratch it for me. So if ur like me, budget for mor. Mtn is d cheapest of d 4 gsm operators.
Download,experiment repeat.

uken73: I have sent you a mail. You may want to delete your e-mail address from your last post.

uken73: You are even based in Akwa Ibom. I'm in Akwa Ibom too. It's difficult to get these stuff over here, but you can get someone in Lagos to buy & send it to you. The latest you can grab, the better. VB6 is just damn too old and a serious waste of time.

uken73: Like I said, I'm not into mobile development (yet). But I think the following resources should be of help.

http://devproconnections.com/mobile-development/mobile-development-options-net-developers
http://www.asp.net/mobile
http://xamarin.com/

uken73: VB 6 is good as a 1st language, but you should consider learning the latest version which is VB.NET. Most VB6 programmers found it challenging to port to .NET, so it would be wise to just learn .NET at once.

Kennyinusa: For me i develop Android and windows phone.
I use Java for android and C# for the windows phone.
Meanwhile you can develop cross platform apps using stuffs like HTML/CSS and JS. But i would advice that you stay off those coast at least for now and develop from a more native centric perspective.

To develop for Android, you need to understand the Java Programming language and a lil bit of XML. I would suggest you lookup w3school for head start on XML
The IDE that i use is Eclipse and you can also use Intell J Community edition and Android studio(based on IntellJ).
If you are into continious development, version control or stuffs like that, i would suggest you stick with IntellJ else try Eclipse it is easy to use.

To develop for windows phone from a native centric perspective, you need to understand C# or VB though an understanding of C++ can be handy depending on what you want to achieve.

To develop for iOS you need XCode (IDE), Mac OS (PC), Objective C (Language).

So create a learning curve around this and i believe that the sky is the limit.

And please for God sake get latest materials and Latest IDEs they would help you better.
Get VS2013 for your VB
Thank you

uken73: I'm not into mobile programming (yet), but I would advice that you avoid tools that are too old (like Visual Studio 6).

9japipper: it is mobile compatible but its just preferable you use a pc cus it gets to load so much to your browser. We have plans of making mobile specific version

9japipper: Hello NL programmers, I and my team have been working on a school management project. We just released a beta version for the admin backend. Please help me review the app and tell me your observations and reservations.
God bless

www.unify.com.ng/beta
username:admin1
password:admin1

moruphb: i have a very clean and perfect condition 05 model for sale for 1.2m, send me a pm if you are interested.

ccaramel: https://www.nairaland.com/1789998/tokunbo-2006-gold-toyota-corolla

Only 1.5m