Class.forName how can I invoke a unknown method
I have a code like this:
public class Detonator {
String cName;
String mName;
public Detonator(String className, String methodName) {
cName = className;
mName = methodName;
// in this place I want to do something like cName.mName()
// Is it possible ???
}
Look at java.lang.reflect.*.
Similar Messages
-
How can i invoke a void method in main?
Hi guys I am killing myself over why we use void method if we can't call on it from main.
For example i am trying to create a program to calculate military time. In my main i am trying to call setHour which is void. setHour is supose to check if the input of hour is over 24 and if it is i have to reset hour to 00. But it gives an error that i can't call on that method because it is void.
So how do i invoke it from main?
and
Why do we use void if we can't call on it?
Thanksok here it is mate. It is not finished but pay attention on the setMethods that is what im trying to invoke from main. Here's my methods and then main will be under it.
public class MilitaryTime
private int hour;
private int minute;
private int second;
public MilitaryTime()
hour=0;
minute=0;
second=0;
public MilitaryTime(int hour, int minute, int second)
this.hour=hour;
this.minute=minute;
this.second=second;
public MilitaryTime(MilitaryTime t)
public void setHour(int h)
if(h>=24)
h=00;
else
hour=h;
public void setMinute(int m)
if(m>=60)
m=00;
else
minute=m;
public void setSecond(int s)
if(s>=60)
s=00;
else
second=s;
public int getHour()
return hour;
public int getMinute()
return minute;
public int getSecond()
return second;
public void tick()
second=second+1;
public String toUniversalString()
StringBuffer buffer;
buffer = new StringBuffer();
// add the hour (with leading zero if its neccesary)
if(this.hour < 10)
buffer.append("0");
buffer.append(this.hour).append(":");
// add the minute (with leading zero if its neccesary)
if(this.minute < 10)
buffer.append("0");
buffer.append(this.minute).append(":");
// add the second (with leading zero if its neccesary)
if(this.second < 10)
buffer.append("0");
buffer.append(this.second).append("");
return buffer.toUniversalString();
public String toString()
StringBuffer buffer;
buffer = new StringBuffer();
// add the hour (with leading zero if its neccesary)
if(this.hour < 10)
buffer.append("0");
buffer.append(this.hour).append(":");
// add the minute (with leading zero if its neccesary)
if(this.minute < 10)
buffer.append("0");
buffer.append(this.minute).append(":");
// add the second (with leading zero if its neccesary)
if(this.second < 10)
buffer.append("0");
buffer.append(this.second).append("");
return buffer.toString();
}Here is main where i try and call setHour to check for accuracy.
import javax.swing.*;
public class TestMilitaryTime
public static void main(String[]args)
String sHour=JOptionPane.showInputDialog(null,
"Input Hour:", "Military Time",JOptionPane.QUESTION_MESSAGE);
int hour=Integer.parseInt(sHour);
String sMinutes=JOptionPane.showInputDialog(null,
"Input minutes:", "Military Time",JOptionPane.QUESTION_MESSAGE);
int minutes=Integer.parseInt(sMinutes);
String sSeconds=JOptionPane.showInputDialog(null,
"Input seconds:", "Military Time",JOptionPane.QUESTION_MESSAGE);
int seconds=Integer.parseInt(sSeconds);
MilitaryTime time= new MilitaryTime(hour,minutes,seconds);
System.out.println(time.setHour());
System.out.println("The military time is you enterd is "+time.toString());
Everything else works fine except the setHour thing.
Thanks -
How can i invoke the set method before value change listener?
Hi,
My code is like this:
<af:selectManyCheckbox value="#{bean.statusList}"
binding="#{bean.statusCheckBox}"
label=" " autoSumit="true"
valueChangeListener="#{bean.changeStatusList}"
id="dc_smc1" layout="vertical"">
<f:selectItems value="#{bean.statusBuckets}"
id="statusBuckets"/>
</af:selectManyCheckbox>
public void changeStatusList(ValueChangeEvent valueChangeEvent)
//in this method, i want to set the statusList by myself, this is not the same with the ui.
public void setStatusList(List<String> statusList)
this.statusList = statusList;
public List<String> getStatusList()
return statusList;
As i set the autoSumit="true", then no matter what i set the statusList in the method changeStatusList, it will be reset the value after invoke the method setStatusList, Therefore, it will always change the checkbox status through ui operation, i cannot change it through code.
Pl help me!
Thanks,
EmmaEmma, which jdev version do you use?
As you have set the value property to the list you try to change in the valueChangeListener method this is expected behavior. If the list is bound to the af:selectManyCheckbox values you can't change it with a set method.
It would help if you tell us what you are trying to do in a broader scope.
Timo -
How can one invoke a WebLogic EJB from a BPEL Server hosted on OC4J?
How can one invoke a WebLogic EJB from a BPEL Server hosted on OC4J?
Reason I ask is I keep getting this error:
javax.naming.NoInitialContextException: Cannot instantiate cla
ss: weblogic.jndi.WLInitialContextFactory [Root exception is java.lang.ClassNotF
oundException: weblogic.jndi.WLInitialContextFactory]
Note: I am using <bpelx:exec> as a way to execute some java program.
Essentially my java client (essentially an EJB client hosted on Oc4J) needs access to wlclient.jar since it needs access to weblogic.jndi.WLInitialContextFactory. I have a EJB client running on BPEL server hosted on Oc4J that needs to access some EJBs hosted on weblogic.
Where do I place this wlclient.jar so that BPEL PM can start peacefully and at runtime discover the InitialContextFactory classes?
Placing it in the j2ee/home/applib doesn't solve the problem. The server fails to start up if I do this
I tried placing it in BPEL-INF\lib directory ...
I still get the same exception...see below for exception dump
I verified the BPEL suitcase, and it in fact does contain the jar file wlclient.jar
integration\orabpel\domains\default\deploy contains the bpel_BPELProcess2_1.0.jar file and snapshot of that is as follows:
<PRE>
│ bpel.xml
│ BPELProcess2.bpel
│ BPELProcess2.jpr
│ BPELProcess2.wsdl
│ bpel_BPELProcess2_1.0.jar
│ build.xml
│ buildxml.copy
│ graphics.xml
│
├───BPEL-INF
│ └───lib
│ myEJB.jar
│ wlclient.jar
│
├───META-INF
│ MANIFEST.MF
│
└───output
bpel_BPELProcess2_1.0.jar
</PRE>
I tried using the BPEL-INF\jar directory...Is this something the obant automatically detects? or do I have to modify the build.xml? I created this directory and let Jdev deploy to local BPEL server->default domain handle it
#####################3
I even tried copying the wlclient.jar to
integration\orabpel\system\classes but this doesn't help since the BPEL PM fails to start if I explode this jar into this directory.
In short,where do I place the wlclient.jar so that this exception can be contained.
I edited the build.xml to point to the jar, that too didn't work, unless I made some mistake in the file
<bpelc classpath="${basedir}/BPEL-INF/classes;${home}/system/classes;${home}/lib/j2ee_1.3.01.jar;${basedir}/BPEL-INF/jar/wlclient.jar" input="${basedir}/bpel.xml" rev="${rev}" deploy="${deploy}" />
</target>
</project>
DETAILS on ERROR
I get the following error
Process "BPELProcess2" (revision "1.0") successfully compiled.
<2005-12-14 09:17:55,770> <INFO> <default.collaxa.cube.engine.deployment> Proces
s "BPELProcess2" (revision "1.0") successfully loaded.
05/12/14 09:18:36 weblogic.jndi.WLInitialContextFactory
javax.naming.NoInitialContextException: Cannot instantiate cla
ss: weblogic.jndi.WLInitialContextFactory [Root exception is java.lang.ClassNotF
oundException: weblogic.jndi.WLInitialContextFactory]
05/12/14 09:18:36 at javax.naming.spi.NamingManager.getInitialContext(Nami
ngManager.java:652)
05/12/14 09:18:36 at javax.naming.InitialContext.getDefaultInitCtx(Initial
Context.java:243)
05/12/14 09:18:36 at javax.naming.InitialContext.init(InitialContext.java:
219)
05/12/14 09:18:36 at javax.naming.InitialContext.<init>(InitialContext.jav
a:195)
05/12/14 09:18:36 at com.ejb.test.MapFinder.getDefaultMapName(Map
Finder.java:37)
##################3
with the bpelx all I have is two lines of code that creates a java object and calls a method on it.
The method does this:
private String initialContextFactory = "weblogic.jndi.WLInitialContextFactory";
private String providerUrl = "t3://localhost:7001";
private String urlPkgPrefixes = "";
private String mapEjbJndiName = "ejb/mycompany/Redlands";
public String getDefaultMapName() {
try {
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, getInitialContextFactory());
env.put(Context.PROVIDER_URL, getProviderUrl());
if (getUrlPkgPrefixes() != null && !getUrlPkgPrefixes().equals(""))
env.put(Context.URL_PKG_PREFIXES, getUrlPkgPrefixes());
System.out.println(" " + getInitialContextFactory());
System.out.println(" " + getProviderUrl());
System.out.println(" " + getUrlPkgPrefixes());
System.out.println(" " + getEjbName());
// Get a naming context
context = new InitialContext(env);
Object ms = context.lookup(getEjbName());
MyEJBHome home = (MyEJBHome ) PortableRemoteObject.narrow(ms, MyEJBHome.class);
myEjb = home.create();
return myEjb.getDefaultName();
} catch (RemoteException re){
System.out.println(re.getCause().getMessage());
catch (Exception ex) {
ex.printStackTrace();
return null; //if unable to resolve the context factory etc...
}I did exactly as you suggested. I edited the application.xml and added this
<library path="C:\ArcGIS\test\bea\wlclient.jar"/>
I didn't add weblogic because the needed classes were all in wlclient.jar
I also edited the BASE_OB_CLASSPATH to include this jar.
Here is the result when I just start BPEL PM Server. Somehow BPEL PM doesn't like to have wlclient.jar in its classpath during startup.
Failed to create "worker" bean; exception reported is: "javax.naming.NameNotFoun
dException: remaining name: env
at weblogic.j2eeclient.SimpleContext.lookup(SimpleContext.java:49)
at weblogic.j2eeclient.SimpleContext.lookup(SimpleContext.java:57)
at weblogic.j2eeclient.SimpleContext.lookup(SimpleContext.java:62)
at javax.naming.InitialContext.lookup(InitialContext.java:347)
at com.collaxa.cube.engine.ejb.impl.WorkerBean.ejbCreate(WorkerBean.java
:49)
at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.evermind.server.ejb.MessageDrivenHome.getInstance(MessageDrivenHo
me.java:1235)
at com.evermind.server.ejb.MessageDrivenHome$2.run(MessageDrivenHome.jav
a:1150)
at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(Relea
sableResourcePooledExecutor.java:186)
at java.lang.Thread.run(Thread.java:534)
<2005-12-29 13:39:05,281> <ERROR> <collaxa> <ServerManager::loadAllDomains>
ORABPEL START-UP ERROR!!!!!!!!
OraBPEL run-time system failed to start due to exception:
Could not initialize jms connection pool.
Could not initialize connection pool for connection factory "java:comp/env/jms/
ollaxa/BPELInvokerQueueFactory"; the reason is remaining name: env/jms/collaxa/
PELInvokerQueueFactory.
Note: So what I did was to removed the entry from application.xml and tried with just obsetenv.bat having the wlclient.jar added to it. This too failed!!
Here is a snapshot of the error I got.
Process "BPELProcess2" (revision "1.0") successfully compiled.
<2005-12-29 13:53:11,207> <INFO> <default.collaxa.cube.engine.deployment> Proces
s "BPELProcess2" (revision "1.0") successfully loaded.
05/12/29 13:53:32 Cannot instantiate class: weblogic.jndi.WLInitialContextFactor
y
05/12/29 13:53:32 javax.naming.NoInitialContextException: Cannot instantiate cla
ss: weblogic.jndi.WLInitialContextFactory [Root exception is java.lang.ClassNotF
oundException: weblogic.jndi.WLInitialContextFactory]
05/12/29 13:53:32 at javax.naming.spi.NamingManager.getInitialContext(Nami
ngManager.java:652)
05/12/29 13:53:32 at javax.naming.InitialContext.getDefaultInitCtx(Initial
Context.java:243)
05/12/29 13:53:32 at javax.naming.InitialContext.init(InitialContext.java:
219)
05/12/29 13:53:32 at javax.naming.InitialContext.<init>(InitialContext.jav
a:195)
05/12/29 13:53:32 at com.esri.adf.ejb.test.MapFinder.getDefaultMapName(Map
Finder.java:57)
05/12/29 13:53:32 at bpel.p0.ExecLetBxExe1.execute(ExecLetBxExe1.java:62)
05/12/29 13:53:32 at com.collaxa.cube.engine.ext.wmp.BPELXExecWMP.__execut
eStatements(BPELXExecWMP.java:49)
05/12/29 13:53:32 at com.collaxa.cube.engine.ext.wmp.BPELActivityWMP.perfo
rm(BPELActivityWMP.java:185)
05/12/29 13:53:32 at com.collaxa.cube.engine.CubeEngine.performActivity(Cu
beEngine.java:3398)
05/12/29 13:53:32 at com.collaxa.cube.engine.CubeEngine.handleWorkItem(Cub
eEngine.java:1905)
05/12/29 13:53:32 at com.collaxa.cube.engine.dispatch.message.instance.Per
formMessageHandler.handleLocal(PerformMessageHandler.java:75)
05/12/29 13:53:32 at com.collaxa.cube.engine.dispatch.DispatchHelper.handl
eLocalMessage(DispatchHelper.java:100)
05/12/29 13:53:32 at com.collaxa.cube.engine.dispatch.DispatchHelper.sendM -
How can I invoke the web service manually in websphere?
Hi
I've developed a webservice application using Rational Application Developer (RAD). I deployed it in a websphere 6.1 application server, using the administration console to import the war file that I had previously exported with RAD.
My webservice application is listed in the "Enterprise Applications" section of websphere's administration console as started.
My question is: how can I invoke the web service manually? Is there some kind of websphere generated webpage that I can use to call it manually?
I tried http://<server:port>/<contextroot> and http://<server:port>/<contextroot>/<servicename> in a webbrowser, but it doesn't work. Is it possible to invoke the web service manually, or do I need to develop a client?
Thanks in advance
PedroHi Bo Wang,
Go to the Portal -> System Administration -> System Configuration
-> Portal Content folder
-> Open Visual Composer folder
There you can see the Webservice Systems you have created through VC.
You can delete the unwanted system here.
Regards,
Shemim -
What is inner class ,and how can I use it?thanks
what is inner class ,and how can I use it?thanks
Theres a whole chapter here http://developer.java.sun.com/developer/Books/certification/certbook.html (thanks to SSvetlana for pointing this one out).
Col -
How can i invoke a file chooser dialog box with out using input type=file
how can i invoke a file chooser dialog box with out using <input type=file> can any one help me mail me to [email protected]
You could use an applet...
Or maybe Javascript has some way to do it. -
Sorry for the typographical mistake.
Please read the question as:"How do i get a list of all Roles defined under a particular OrganizationalUnit? How can i use LDAPConnection.search method for this?" -
How can i use Catalog in Method Type?
Dear Experts,
How can i use Catalog in Method Type?
I want to use Multiple method type mean require selection option(help from catalog)and also need to entere the result against certain parameters. So how can i do this possible ?
Except use of additional infrmation field
Regards,
AbhishekHi,
Can i provide selection option F4 help at Method while enteing the result?
Because for 1 MIC as per buyer method testing different so it will come alternately.
i.e i have 3 methods which comes altarnative for one MIC
TST_ISO
TST_AATC
TST_ASTM
So how it is possible??? -
How can I call the create method in BO from Application Service
Hello!
When I create a Business Object, CAF generates some methods automatically.
How can I call the create method in the BO from Application Service logic?
When i call the method then the entityManager and the sessionContext is NULL.
How can I initialize this?
Can anybody help me?
Thanks, ThomasIf you are using CE 7.11...
1) In the Application Services, add the BO as dependant object in dependencies tab.
2) In the implemention, add the following codes to call create method of the BO:
this.get<BO>.createMethod();
julius -
How can i deprecate a superclass method ?
Hi all,
How can i deprecate a superclass method from a subclassQthe OP: That makes no sense. It is by definition valid to call that method because it is valid for the superclass, and every instance of the subclass is also an instance of the superclass.
-
How can I change the payment method to None with gift card balance.
How can I change the payment method to None with gift card balance?
I already have an Apple ID account with no credit card but when I try to log in download free app it says Apple ID has not been used in iTunes store please review your account and it appears the billing info and there's no none in the option..how can I solve this so that I can used my Apple ID and can download free apps?Hi ..
Help here > Why can’t I select None when I edit my payment information?HHi -
How can I invoke a method on a subclass based on the runtime type?
Hi all,
I have defined a base class OrderDetail, and 2 subclasses which extend it: OrderDetailSingleReservation and OrderDetailMonthReservation. Furthermore, I have a method:
public Order order_generate(OrderDetail orderDetail) {
if (orderDetail instanceof OrderDetailSingleReservation) {
return order_generate((OrderDetailSingleReservation) orderDetail);
} else if (orderDetail instanceof OrderDetailMonthReservation) {
return order_generate((OrderDetailMonthReservation) orderDetail);
} else {
Misc.alert("orderAndInvoice_Generate(GENERIC): unsupported type.");
return null;
}The type of this method's parameter is OrderDetail, as you can see. (This particular method only serves as a kind of dispatcher and is therefore not very interesting in itself, but the same pattern using 'instanceof' occurs in a codebase I am working on several times, and I would like to factor it out if possible.)
My question: it seems that the invocation of order_generate() from within this method requires an explicit downcast to one of the two subclasses. If not, java invokes the method on the superclass. But at runtime, the JVM knows what type of object it is dealing with, right? So is there no way to do this without the explicit downcast?
A similar problem occurs when trying to invoke a method on an object whose type is one of the subclasses; the method on superclass is called, instead of the one in the appropriate subclass that overrides it.
Any help would be greatly appreciated!
Thanks,
ErikThanks for your replies! I was editing my post last night to clarify it, but my connection went down and the edit was lost :(
Anyway, yes, it should be done with polymorphism. I was constructing an example using the famous Animal, Cat and Dog classes to demonstrate my question more clearly, and to my surprise the problem does not occur in my example code.
LRMK: Invoking a method such as in your example, where the method is inside the class itself, works fine. However for MVC's sake, I have a separate class called Invoicing with methods as below:
class invoicing
// the method for the superclass
public Invoice invoice_create(OrderDetail orderDetail) {
System.out.println("type: " + orderDetail.getClass());
return null;
// the method for one of the subclasses (this method is being not invoked)
public Invoice invoice_create(OrderDetailSingleReservation orderDetail) {
return null;
// ...nor is this one.
public Invoice invoice_create(OrderDetailMonthReservation od) {
return null;
}Now I attempt to invoke these methods:
// create example objects
OrderDetailSingleReservation odSingle = new OrderDetailSingleReservation();
OrderDetailMonthReservation odMonth = new OrderDetailMonthReservation();
// this call displays "odSingle type: OrderDetailSingleReservation"
System.out.println("odSingle type: " + odSingle.getClass());
// this call displays "odMonth type: OrderDetailMonthReservation"
System.out.println("odMonth type: " + odMonth.getClass());
// this call invokes Invoicing.invoice_create(OrderDetail)
// instead of Invoicing.invoice_create(OrderDetailSingleReservation)
Invoicing.invoice_create(odSingle);
// this call invokes Invoicing.invoice_create(OrderDetail)
// instead of Invoicing.invoice_create(OrderDetailMonthReservation)
Invoicing.invoice_create(odMonth);So these calls will invoke the method for the superclass, i.e. Invoicing.invoice_create(OrderDetail od). That method then then executes the System.out.println() call which displays the class type of its parameter as one of { OrderDetailSingleReservation | OrderDetailMonthReservation }, that is, the expected subclass types!
So the dynamic dispatch isn't working the way I would expect it to. If I do the explicit if-else checking using instanceof, as described in my first post, the correct methods are called.
I hope the problem is somewhat clearer now. I am a bit lost as to what might be causing this, or how to monitor what's going on inside the jvm. Any ideas? BTW, the OrderDetail class and its subclasses are JPA entities (though I don't think it should matter).
Thanks!
Erik -
Class.forName, how to use it in the case?
we have a java application:
c:\app\TestForName.class
inside the app, there is a call:
Class.forName("ClassLib");
ClassLib.class is a simplest class for testing with no package.
ClassLib.class can be in any directory except the app's directory
c:\app
because ClassLib.class stands for our library class for multiple projects and multiple uses, it is not allowed to be in a special app directory.
and, ClassLoader and URLClassLoder are not suitable in our case.
i tried following 3 ideas, none of them is OK, please help.
1. put ClassLib.class in directory
c:\lib\
(that is c:\lib\ClassLib.class)
call application with command -cp
java -cp c:\lib;....; TestForName
(method Class.forName("ClassLib") call is inside TestForName.class)
2. put ClassLib.class in
c:\jdk\bin\
(VM says it is one of "java.library.path")
java -cp ....; TestForName
3. put ClassLib.class in
c:\jdk\JAR\classes\
(VM says if is one of "sun.boot.class.path")
java -cp ....; TestForName
i really wondering how to make Class.forName() call successfuf inside application TestForName.class
1. which directory is right place for ClassLib.class
2. how to change command line or java code inside TestForName.class
thx for any help.Why don't u use a class loader. Try this code
// loader class
public class Loader extends ClassLoader {
String path;
public Loader(String path) {
this.path = path;
public Class findClass(String name) {
byte[] b = loadClassData(path+name+".class");
return defineClass(name, b, 0, b.length);
private byte[] loadClassData(String name) {
File file = new File(name);
byte[] data = null;
try {
InputStream in = new FileInputStream(file);
data = new byte[ (int) file.length()];
for (int i = 0; i < data.length; i++) {
data[i] = (byte) in.read();
catch (IOException ex) {
file = null;
return data;
// in your caller class use
Loader loader = new Loader(libPath); // lib path may be taken from a command line arg
Object main = loader.loadClass("ClassLib", true).newInstance();I think this is what u r looking for
Uditha Nagahawatta -
JDev TP3 / UML Class Diagram / How can I specify a derivative attribute?
Hello,
I'm trying to put derivatives (or calculated) attributes such as "age" or "price" in a class of UML diagram. In all of UML books that I've seen, a derivative attribute is represented with a "/" and the attribute's name. For example, "/age" or "/price". But in the class diagram of JDeveloper I can't put "/" in the name of attribute. So, how can I specify a derivative attribute?
Thanks in advance,
JVNUnfortunately, it is not possible to denote derived attributes in TP3. Bug 6915067 has been logged to address this in a future version.
Thanks, Guus (JDev PM)
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