I have a managed bean that returns a number of different properties that describe an application. So it can be called to return the FilePath of a database by calling
appProps[sessionScope.ssApplication].helpFilePath
or
appProps[sessionScope.ssApplication].ruleFilePath
I'm trying to work out a generalized case where I need to call for the file path based on a value in a compositeData variable which can take on any one of 4 different values help/rule/app/main.
I wrote this SSJS and it works but I am wondering if there is a better way to make it work:
var target:String = compositeData.DBSource;
switch (target){
case "app" :
return appProps[sessionScope.ssApplication].appFilePath;
break;
case "help" :
return appProps[sessionScope.ssApplication].helpFilePath;
break;
case "rule" :
return appProps[sessionScope.ssApplication].ruleFilePath;
break;
case "main" :
return appProps[sessionScope.ssApplication].mainFilePath;
break;
}
I can't figure out if there is a way to compute the method by using compositeData.DBSource + "FilePath" . when I try this I get an error that the method does not exist. Using the SSJS code above is not really a problem but it just seems a bit redundant.
You can make a new method in your managed bean that takes target as an argument:
public String getFilePath(String target) {
String returnValue = "";
if (target.equalsIgnoreCase("app")) {
returnValue = this.appFilePath;
} else if (target.equalsIgnoreCase("help")) {
returnValue = this.helpFilePath;
} else if (target.equalsIgnoreCase("rule")) {
returnValue = this.ruleFilePath;
} else if (target.equalsIgnoreCase("main")) {
returnValue = this.mainFilePath;
}
return returnValue;
}
And then call it like this in your SSJS:
appProps[sessionScope.ssApplication].getFilePath(compositeData.DBSource);
Related
I'm trying to write a very simple C# program in VS2015. I keep getting a message "The name (variable) does not exist in the current context." This is true for both my bool variable and string variable.
namespace PTouch
{
public class PTouch
{
bool lb_rc;
string strLabel;
lb_rc = false;
strLabel = "C:\BenchTop10\Standard 1in.lbx";
bpac.Document doc = new Document();
lb_rc = doc.Open("C:\BenchTop10\Standard 1in.lbx");
if lb_rc != false
{
doc.StartPrint("", 0);
doc.PrintOut(1, 0);
doc.EndPrint();
doc.Close();
}
else
{
MessageBox.Show("Open Error: " + doc.ErrorCode);
}
}
}
There are probably several problems with this code, but the first one is error about the variables not existing in the current context.
Any assistance is greatly appreciated.
I just discovered the problem... All the code has to be inside of a method, not just the class. I added a method to the class,
public void PrintLabel()
{ bool lb_rc; ... }
All errors cleared up, except MessageBox...
Thank you,
Tracy
I've got a GUI with a TabControl. Each new TabPage is created via a new Thread. I want to call this->tabControl->TabCount, but the tabControl is owned by a thread other than the one I'm calling from. Therefore, I need to Invoke a delegate. However, all the examples I find online show printing to std::cout from each of the delegate methods. I need a return value, in this case an int.
delegate int MyDel();
int InvokeTabCount()
{
if (this->InvokeRequired)
{
MyDel^ del = gcnew MyDel(this, &MyTabControl::InvokeTabCount);
auto temp = this->Invoke(del); // can't just "return this->Invoke(del)"
return temp; // Invoke() returns a System::Object^
}
else
{
return this->tabControl->TabCount;
}
}
void CreateNewTab()
{
// do stuff
this->tabControl->TabPages->Insert(InvokeTabCount() - 1, myNewTab); // insert a tab
this->tabControl->SelectTab(InvokeTabCount() - 2); // OutOfBounds and tabPageNew
}
System::Void MethodToAddNewTabPage() //actually a click event but whatever
{
System::Threading::Thread^ newThread =
gcnew System::Threading::Thread(
gcnew System::Threading::ThreadStart(this, &MyTabControl::CreateNewTab));
newThread->Start();
}
Currently, my InvokeTabCount() method is returning -1 when I simply this->Invoke(del) without returning it. And I am unable to return it because my method expects to return an int instead of a System::Object^ which is what Invoke() returns. However, when debugging I find that auto temp contains the value 2 which is correct. And temp->ToString() contains the value "2" which would also be correct.
How do I return this->Invoke(del)?
Do I need to set the value of a global variable from within my InvokeTabCount() method? I suppose I could find a way to translate from System::String^ to std::string to utilize std::stoi(), but that seems like an odd workaround.
Current solution:
delegate int MyDel();
int InvokeTabCount()
{
if (this->InvokeRequired)
{
MyDel^ del = gcnew MyDel(this, &MyTabControl::InvokeTabCount);
auto temp = this->Invoke(del);
return int::Parse(temp->ToString());
}
else
{
return this->tabControl->TabCount;
}
}
The result is an integer, boxed and contained in an Object^ reference. You should be able to simply cast it to int.
If you want to be extra safe, do a null check and verify that temp->GetType() returns int::typeid, but that's probably overkill since you're creating the delegate (still in the typed form) right there.
I want to know weather is is possible or not, a way to call different classes on the basis of an integer value without conditional statements like switch case?
What I am having is:
int val = // getting some value here from a method
String data = // getting some value here from a method
switch(val)
{
case 1:
{
new TempClass1(data);
break;
}
case 2:
{
new TempClass2(data);
break;
}
}
What I want is like:
int val = // getting some value here from a method
String data = // getting some value here from a method
new TempClass(val, data);
This should call the object of TempClass1 or TempClass1 as per "val"
Any help will be appreciated.
Maybe use a Factory for the classes, assuming your two classes share a base class named TempBaseClass:
class TempClassFactory {
static public TempBaseClass getTempClass(int val, String data)
{
switch(val)
{
case 1:
{
return new TempClass1(data);
break;
}
case 2:
{
return new TempClass2(data);
break;
}
default:
throw new Exception("Bad value");
}
}
}
int val = // getting some value here from a method
String data = // getting some value here from a method
TempClassFactory::getTempClass(val, data);
I think we are having an issue on using Monitor::TryEnter and Monitor::Exit on a String (I suppose this is the issue, but I'm looking for some extra information).
if (Monitor::TryEnter(m_sLogFile, 200)) {
try {
m_sLogFile = IO::Path::GetDirectoryName(Application::ExecutablePath) + "\\" + LOG_FILE_DEFAULT;
// SOME EXTRA CODE
}
finally {
Monitor::Exit(m_sLogFile);
}
}
[m_sLogFile is a String declared in my class]
The SynchronizationLockException is thrown on Monitor::Exit call, with this message:
Object synchronization method was called from an unsynchronized block
of code
I want to be sure that error is that we are locking the string and we are changing its content.
The problem is not that you are using a string for Monitor.Enter/Exit, the problem is that you are using one string for Enter and different one for Exit:
if (Monitor::TryEnter(m_sLogFile, 200)) {
try {
m_sLogFile = IO::Path::GetDirectoryName(Application::ExecutablePath) + "\\" + LOG_FILE_DEFAULT;
// SOME EXTRA CODE
}
finally {
Monitor::Exit(m_sLogFile);
}
}
See the m_sLogFile = .... inside?
You need to use a field which doesn't change (something like readonly object m_Lock; should be sufficient).
I'm trying to filter some records using the RecordFilter interface. In my app I have a couple of interfaces similar to this one, on which the user can enter an ID or Name (he/she could enter both or neither of them too)
Here's what I've done so far:
The Customer filter.
Here if the user didn't enter an ID, I pass 0 as a default value, that's why I evaluate customerID!=0
public class CustomerFilter implements RecordFilter {
private String mName_Filter;
private int mID_Filter;
public CustomerFilter(String name_Filter, int id_Filter) {
this.mName_Filter = name_Filter.toLowerCase();
this.mID_Filter = id_Filter;
}
public boolean matches(byte[] candidate) {
try {
ByteArrayInputStream bis = new ByteArrayInputStream(candidate);
DataInputStream dis = new DataInputStream(bis);
int customerID = dis.readInt();
String customerName = dis.readUTF().toLowerCase();
if ((customerName != null && customerName.indexOf(mName_Filter) != -1) && (customerID != 0 && customerID == mID_Filter))
return true;
if (customerName != null && customerName.indexOf(mName_Filter) != -1 && customerID == 0)
return true;
if (customerName == null && (customerID != 0 && customerID == mID_Filter))
return true;
if (customerName == null && customerID == 0)
return true;
} catch (IOException ex) {
//What's the point in catching a exception here???
}
return false;
}
}
The search method:
Note: This method is in a class that I call "RMSCustomer", in which I deal with everything related to RMS access. The search method receives two parameters (id and name) and uses them to instantiate the filter.
public Customer[] search(int id, String name) throws RecordStoreException, IOException {
RecordStore rs = null;
RecordEnumeration recEnum = null;
Customer[] customerList = null;
try {
rs = RecordStore.openRecordStore(mRecordStoreName, true);
if (rs.getNumRecords() > 0) {
CustomerFilter filter = new CustomerFilter(name, id);
try {
recEnum = rs.enumerateRecords(filter, null, false);
if (recEnum.numRecords() > 0) {
customerList = new Customer[recEnum.numRecords()];
int counter = 0;
while (recEnum.hasNextElement()) {
Customer cust;
int idRecord = recEnum.nextRecordId();
byte[] filterRecord = rs.getRecord(idRecord);
cust = parseRecord(filterRecord);
cust.idRecord = idRecord;
customerList[counter] = cust;
counter++;
}
}
else{
customerList = new Customer[0];
//How to send a message to the midlet from here
//saying something like "No Record Exists.Please select another filter"
}
} finally {
recEnum.destroy();
}
}
else{
//How to send a message to the midlet from here
//saying something like "No Record Exists.Please Add record"
}
} finally {
rs.closeRecordStore();
}
return customerList;
}
Even though, the code shown above works I still have some questions/problems:
In the Filter :
1) How can I improve the code that evaluates the possible values of the filters (name,id)? What if I had more filters?? Will I have to test all the possible combinations??
2) If the user doesn’t enter neither a ID nor a name, should I display all the records or should I display a message "Please enter a name or ID"?? What would you do in this case?
3) Why do I have to put a try-catch in the filter when I can't do anything there?? I can't show any alert from there or can I?
In the search method:
1) How can I show a proper message to the user from that method? something like "No records" (see the "ELSE" parts in my code
Sorry If I asked too many questions, it's just that there's any complete example of filters.
Thanks in advance
How can I improve the code that evaluates the possible values of the
filters (name,id)?
The ID is the first field in the record and the fastest one to search for. If the Id matches, It doesn't really matter what the customer name is. Normally you'll be looking for the records where the ID matches OR the customer name matches, so once the ID matches you can return true. This is my proposal for the CustomerFilter class:
public class CustomerFilter implements RecordFilter {
private String mName_Filter;
//Use Integer instead of int.
//This way we can use null instead of zero if the user didn't type an ID.
//This allows us to store IDs with values like 0, -1, etc.
//It is a bit less memory efficient,
//but you are not creating hundreds of filters, are you? (If you are, don't).
private Integer mID_Filter;
public CustomerFilter(String name_Filter, Integer id_Filter) {
this.mName_Filter = normalizeString(mName_Filter);
this.mID_Filter = id_Filter;
}
//You should move this function to an StringUtils class and make it public.
//Other filters might need it in the future.
private static String normalizeString(final String s){
if(s != null){
//Warning: you might want to replace accentuated chars as well.
return s.toLowerCase();
}
return null;
}
public boolean matches(byte[] candidate) {
ByteArrayInputStream bis = new ByteArrayInputStream(candidate);
DataInputStream dis = new DataInputStream(bis);
try {
if(mID_Filter != null){
//If the ID is unique, and the search is ID OR other fields, this is fine
int customerID = dis.readInt();
if(mID_Filter.intValue == customerID){
return true;
} else {
return false;
}
}
if(mName_Filter != null){
String customerName = normalizeString(dis.readUTF());
if(customerName != null && customerName.indexOf(mName_Filter) != -1){
return true;
}
}
if(mID_Filter == null && mName_Filter == null){
return true; // No filtering, every record matches.
}
} catch (IOException ex) {
//Never swallow exceptions.
//Even if you are using an underlying ByteArrayInputStream, an exception
//can still be thrown when reading from DataInputStream if you try to read
//fields that do not exists.
//But even if no exceptions were ever thrown, never swallow exceptions :)
System.err.println(ex);
//Optional: throw ex;
} finally {
//Always close streams.
if(bis != null){
try {
bis.close();
} catch(IOException ioe){
System.err.println(ioe);
}
}
if(dis != null){
try {
dis.close();
} catch(IOException ioe){
System.err.println(ioe);
}
}
}
return false;
}
}
What if I had more filters?? Will I have to test all the possible
combinations??
It depends on your project. Usually the ID is unique and no two records exist with the same id. In this case you should explicitly design the screen so that the user understands that either he types an Id, or else he fills in the other fields. The condition would be like this:
idMatches OR (field1Matches AND field2Matches AND ... fieldNMatches)
If the user types nothing, then all records will be returned.
But then again this is more a UX issue, I don't know if it is valid for your requirements.
From the programming point of view, what is clear is that the more fields you add, the more messy your filter will became. To prevent this, you could use patterns like Decorator, Composite, and even Chain of responsibility. You'll probably have to trade good design for performance though.
If the user doesn’t enter neither a ID nor a name, should I display
all the records or should I display a message "Please enter a name or
ID"?? What would you do in this case?
It depends. Is there any other way to view all records? If so, then show the message.
Why do I have to put a try-catch in the filter when I can't do
anything there?? I can't show any alert from there or can I?
You shouldn't. This class is only responsible of filtering, not of interacting with the user. You can still log the error from the catch clause, and then throw the exception again. That will propagate the exception up to RMSCustomer.search, so whatever client code is calling that function will handle the exception in the same way you are handling the other ones thrown by that method. But keep the finally clause to close the streams.
How can I show a proper message to the user from that method?
something like "No records" (see the "ELSE" parts in my code)
You shouldn't do anything related to the GUI (like showing dialogs) from the RMSCustomer class. Even if you are not using the Model-View-Controller pattern, you still want to keep your class focused on a single responsibility (managing records). This is called the Single responsibility principle.
Keeping your class isolated from the GUI will allow you to test it and reuse it in environments without GUI.
The no records case should be handled by the screen when there are zero results. An array of lenght == 0 is fine here, and the screen will show the "No results" message. For other kinds of errors, you can extend the Exception class and throw your own custom exceptions, i.e: RecordParsingException, from the RMSCustomer.search method. The screen class will then map the different exceptions to the error message in the language of the user.