A Run question.

[nomad]

I have a question in which I want to run my java program.
I'm using Eclipse as my application.
When I want to run my program I do a right-click on the mouse and choose
Run as (arrow down to) run...
A Window called Run shows on the screen.
In the Main class: I have a chose to make by pushing the Search...button
In doing so I have a list of options to chose from.
Matching types which has my project (Employee) or there is another on
under ----Workspace matches------ which again it is listed (Sometimes it listed)

Question is which one do I use. I get an Erros in Project Window.
Erros exist in required Project.FirstJavaProject.
Contune launch?
I can not figure out where the errors are at considering I'm usign Eclipse.



thanks
damon
PS no matter which one I use I get an error.

[JosAH]

When you navigate to Window > Show View > Problems you can see details
of all problems in all open projects. Click on one of the problems and Eclipse
will open the corresponding source for you. Note that the left border of every
source show you the lines which contain errors. If you move your mouse over
those little icons you get a nice description of the error again.

kind regards,

Jos

[nomad]

Thanks Jos...
I did what you told me to do...
the error was listed as
java.lang.NoSuchMethodError: main
Exception in thread "main"

How do I go about find out how to fix this error.
Do you need me to post my code....

thanks
nomad

[JosAH]

Thanks Jos...
I did what you told me to do...
the error was listed as
java.lang.NoSuchMethodError: main
Exception in thread "main"

How do I go about find out how to fix this error.
Do you need me to post my code....

thanks
nomad

The JVM (Java Virtual machine) always starts one of your classes by calling
the public static void main(String[] args) method in that class. In your case
that particular class doesn't contain such a method (NoSuchMethodError: main)

You have to define that method.

kind regards,

Jos

[nomad]

that's what I thought it meant.
but I have this at the end of my project...

Thanks
nomad
ps is this right....
The rest of the projecgt is done with one class, one public class and severl public void...

    public static void main(String[] args) {
 
        Employee_listing employeelist = new Employee_listing();
        Scanner input_flag = new Scanner(System.in);
 
        int choice;
        System.out.println("Make a Section: ");
        System.out.println("1. Enter ");
        System.out.println("2. Find ");
        System.out.println("3. Exit ");
        System.out.print("\nPlease press Enter afer each response");
        System.out.println("Enter your chose please: ");
        choice = input_flag.nextInt();
        input_flag.nextLine();
        if (choice == 1) {// if 1 is select go to makePerson
            employeelist.inputEmployee();
        }// close the if loop
        if (choice == 2) {// if 2 is select go to find
            employeelist.displayMatch();
        }
        if (choice == 3) {
            System.out.printf("Good bye");
        }// close if loop
 
    }// close public static void

[JosAH]

Eclipse uses "launch configurations" to start your Java programs. Navigage
to Run > Run ... and select "Java Application" next press the "new launch"
button at the top left. Then that big dialog comes up; name your new config,
specify the project, the name of the class that contains the main method;
click "apply" and then run your program.

Note that you can have different launch configurations and you can define
new ones for every open project in your workspace.

kind regards,

Jos

[nomad]

Thanks Jos...
I figure it out with your info.
I'm very new to Java and my instructor is not very helpful that goodness for sites like this one.
Your suggestion did not work, until I created a new Prpject. I then moved my Package to the new Project.
But now I get a new error:
Exception in thread "main" java.lang.NullPointerException
at company.Employee_listing.displayMatch(Employee_lis ting.java:223)
at company.Employee_listing.main(Employee_listing.jav a:272)

Note I have a Array and Arraylist.
Any ideal how I can solve this problem

This is my Arraylist

    public void createEmployeeDatabase() {
        Employees = new ArrayList<Employee>();
 
    }

thanks again
nomad

[r035198x]

Thanks Jos...
I figure it out with your info.
I'm very new to Java and my instructor is not very helpful that goodness for sites like this one.
Your suggestion did not work, until I created a new Prpject. I then moved my Package to the new Project.
But now I get a new error:
Exception in thread "main" java.lang.NullPointerException
at company.Employee_listing.displayMatch(Employee_lis ting.java:223)
at company.Employee_listing.main(Employee_listing.jav a:272)

Note I have a Array and Arraylist.
Any ideal how I can solve this problem

This is my Arraylist

    public void createEmployeeDatabase() {
        Employees = new ArrayList<Employee>();
 
    }

thanks again
nomad

Can you post the code for the displayMatch method and indicate which line is line 223?

[JosAH]

Thanks Jos...
I figure it out with your info.
I'm very new to Java and my instructor is not very helpful that goodness for sites like this one.
Your suggestion did not work, until I created a new Prpject. I then moved my Package to the new Project.

Good; may I suggest that you remove the old project including all its resources?
It avoids cluttering you harddisk and cluttering Eclipe's workspace.

But now I get a new error:
Exception in thread "main" java.lang.NullPointerException
at company.Employee_listing.displayMatch(Employee_lis ting.java:223)
at company.Employee_listing.main(Employee_listing.jav a:272)

Note I have a Array and Arraylist.
Any ideal how I can solve this problem

That is also good: it shows that Eclipse can run your project. All you have to
do now is solve your bug ;-)

Navigate to Run > Debug; select your project and select the button "stop in main".
Next Eclipse will switch to its "debugging perspective" where you van step
every single statement of your code; hint: F7 steps over an entire method
while F5 steps "into" the method. Give it a try and experiment with it all a bit.

Pay special attention to the little panel at the top right corner; it displays the
values of all variables in scope.

kind regards,

Jos

[r035198x]

Good; may I suggest that you remove the old project including all its resources?
It avoids cluttering you harddisk and cluttering Eclipe's workspace.



That is also good: it shows that Eclipse can run your project. All you have to
do now is solve your bug ;-)

Navigate to Run > Debug; select your project and select the button "stop in main".
Next Eclipse will switch to its "debugging perspective" where you van step
every single statement of your code; hint: F7 steps over an entire method
while F5 steps "into" the method. Give it a try and experiment with it all a bit.

Pay special attention to the little panel at the top right corner; it displays the
values of all variables in scope.

kind regards,

Jos

Now that you've said it I think that is actually much better than having him post the code.

[JosAH]

Now that you've said it I think that is actually much better than having him post the code.

I saw those big line numbers and just went *eeew!* Nobody wants to plough
through that much of code; Eclipse itself doesn't care though ;-)

kind regards,

Jos

[nomad]

Can you post the code for the displayMatch method and indicate which line is line 223?

line 223 is
for (Employee e : Employees) {

sure here is my code

public void displayMatch() {
        String id_flag = "";
        Scanner input_flag = new Scanner(System.in);
        System.out.println("Enter your chose please AB1234: ");
        id_flag = input_flag.next();
        boolean notfound = true;
        for (Employee e : Employees) {
            String emp = e.getEmpId();
            if (emp.equals(id_flag)) {
                System.out.println("Hello" + ("e.lname"));
                notfound = false;
            }
        }
        if (notfound == true) {
            System.out.println("Error - Employee not found");
// back to menu?
}// need to find out if this needs to go below printing

I would like help and at the same time I'm going to look into Jos suggestion.

thanks
nomad

[nomad]

Question for you...
I have no data in the arraylist. Does this matter.

nomad

[JosAH]

I would like help and at the same time I'm going to look into Jos suggestion.

thanks
nomad

Degugging is an art form; first press the F6 key continuously; somewhere in
your code that null pointer exception is thrown. Restart your debug session
again (see my previous reply) but instead of stepping *over* that last method
that threw the Exception, step *into* it (using the F5 key). Rinse and repeat
until you've nailed the statement that caused the error.

kind regards,

Jos

[r035198x]

line 223 is
for (Employee e : Employees) {

sure here is my code

public void displayMatch() {
        String id_flag = "";
        Scanner input_flag = new Scanner(System.in);
        System.out.println("Enter your chose please AB1234: ");
        id_flag = input_flag.next();
        boolean notfound = true;
        for (Employee e : Employees) {
            String emp = e.getEmpId();
            if (emp.equals(id_flag)) {
                System.out.println("Hello" + ("e.lname"));
                notfound = false;
            }
        }
        if (notfound == true) {
            System.out.println("Error - Employee not found");
// back to menu?
}// need to find out if this needs to go below printing

I would like help and at the same time I'm going to look into Jos suggestion.

thanks
nomad

But you should know by now where the problem is.

[nomad]

is it no data!!!!

[nomad]

I ran the debug a couple of times and I got this flag.

Class file editor

source not found
The source attachment does not contain the source for the file LRUCache.class.
You can change the source attachment by clicking Change Attached Source below:

OK when I click on the button. I have NO idea what I'm suppose to do.
do I select Workspace, or External file... or External Folder.

and I know its trying to find a Class ...

nomad

[JosAH]

is it no data!!!!

An empty list doesn't cause a NullPointerException, it just causes your
for loop to do nothing. My guess for now is that the Employees variable is
simply null (just a guess though).

kind regards,

Jos

[nomad]

I just want to say thanks for the help so far.
A little more info might help you in helping me solve my problem.

When the client select either 1 or 2 and then they type in the id number, there is a boolean that will run a test to find that id.
If they are in the db then it will print out their info.
if they are not in the db then the client is prompt to enter the rest of their info.

Note I can get to the part where they type in the id. After that I get the error flag.

thanks
nomad

[r035198x]

I just want to say thanks for the help so far.
A little more info might help you in helping me solve my problem.

When the client select either 1 or 2 and then they type in the id number, there is a boolean that will run a test to find that id.
If they are in the db then it will print out their info.
if they are not in the db then the client is prompt to enter the rest of their info.

Note I can get to the part where they type in the id. After that I get the error flag.

thanks
nomad

Where have you initialised the Employees collection?

[nomad]

Where have you initialised the Employees collection?

I have not done that part. I need to read up and find out how to do that. Like I said my instructor is not very good. It's an Online class and he hardly helps at all.

thanks.
boy do I feel dumb
nomad

[r035198x]

I have not done that part. I need to read up and find out how to do that. Like I said my instructor is not very good. It's an Online class and he hardly helps at all.

thanks.
boy do I feel dumb
nomad

I wouldn't blame the instructor. Maybe you just need to spend a bit more time with the instructor. They are usually very good.

Well you need to initialize the collection first before you can do any operations with it.

[nomad]

I wouldn't blame the instructor. Maybe you just need to spend a bit more time with the instructor. They are usually very good.

Well you need to initialize the collection first before you can do any operations with it.

I don't mean to down grade him. I fact I never meet him. I have e-mail him with some problems and he responded back, but if I had another question about the project he never responds back.

I learn alot from this site and it's very confusing sometimes, esp with array and arraylist.
I have only taking one programing class and that was SQL a 5 years ago and have not used it hardly at all.

Thanks for the great help and hints.
nomad