Type casting in Java

Hi,
Can we do explicit type casting vigorously in a java class? Im in a situation that i've to do explicit casting 40 to 50 times in a class. Is there any overhead for JVM or any performance issue with this?

Why do you cast so often? It's sounds like a weird design. Casting is pretty cheap.
Kaj

Similar Messages

Could not type cast in java embedding

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
org.xml.sax.InputSource in = (org.xml.sax.InputSource) getVariableData("Invoke_1_getRoutingAndFrameJumpers_OutputVariable","getRoutingAndFrameJumpersResponse");
Document doc = db.parse(in);
In the above code I am trying to type cast the variable getRoutingAndFrameJumpersResponse into org.xml.sax.InputSource so that i can parse.
I am not getting any error during compilation
but I am unable to type cast some run time error is coming in the line were I am type casting but I am not able to see the runtime error.
How can I see the runtime error in java embedding, how to type cast a variable into xml so that I can parse it.

Hi Arun,
Could you try using the bpelx:rename extension in an assign activity enables a BPEL process to rename an element through use of XSD type casting.
<bpel:assign>
<bpelx:rename elementTo="QName1"? typeCastTo="QName2"?>
<bpelx:target variable="ncname" part="ncname"? query="xpath_str" />
</bpelx:rename>
</bpel:assign>
Cheers
A

Dynamic [Runtime] type casting in Java

Hello,
This is my requirement.
I have a method that takes class name as a parameter.
Ex:
Object myMethod(String classname){
Object xyz = getObject(); //userdefine method which returns some object
/*I need to typecast above object with the class name passed as the method parameter*/
/*How can i type cast this object*/
Object obj = (classname) xyz;
return obj;
In the above example, how can i dynamically typecast the object with class whose name is passed as the method parameter?

Hello,
This is my requirement.
I have a method that takes class name as a parameter.
Ex:
Object myMethod(String classname){
Object xyz = getObject(); //userdefine method which
returns some object
/*I need to typecast above object with the class
name passed as the method parameter*/
/*How can i type cast this object*/
Object obj = (classname) xyz;
return obj;
In the above example, how can i dynamically typecast
the object with class whose name is passed as the
method parameter?Perhaps a little more background on the project (what you are trying to do) will help the experts here answer?
/*with a class that takes a noarg constructor*/
public Object getObject(String classname) throws Exception
//might want to get a bit more specific with which exceptions it will throw
return Class.forName(classname).newInstance();
}Do I think this sometimes is indicative (perhaps even more often than not), of a possible design flaw? Yes..
It gets a little trickier if you have constructors (you have to create a Class object representing the string with the .forName(..) ..and then use some reflection to determine constructors and then a bit of logic to determine which of those to use...)
~Dave

Java type casting interesting query

In java semantics
1) float var1=10.5; // is wrong it should be written as
float var1=(float)10.5; //type casting->double to float
or
float var1=10.5f; //type casting
but
2) byte var2=10; // here int to byte type casting should be there according to previous eg.
But this is correct.
Why the 2nd one is correct???

>
I suspect the reason is, that the compiler can check whether it will fit in the second case.
You can't accidentally type
byte b = 128;Whereas with floating point numbers you could accidentally be losing precision, imagining that you're using doubles, when in fact you are using floats. So the extra cast is needed so you understand you're losing precision.

Any way to search for casts in java source code?

Anyone know of a decent way to search your java source files to find all the casts?
I ended up doing a simple text search for
     " = ("(quote marks not included) which works for my code because I am strict about writing my casts with spaces like
     String s = (String) iterator.next();Unfortunately, the above search has all kinds of problems with both false positives and negatives. It picks up lots of irrelevant lines like
     int index = (number > 0) ? 0 : 1;as well as misses casts that appear nested inside expressions like
     ((String) iter.next()).charAt(...)I suppose that one could do a regular expression search for any pair of open and close parens which bound non-blank text, but that would pick up even more non-cast expressions in typical java code.
I think that the only way to properly do this is to have a tool which understands java syntax.
Anyone know of an IDE which will do this? Does IntelliJ or Netbeans support this kind of search?
In case you are wondering why I am interested in this, it is because I am refactoring some code to fully use generics, and searching for casts is one source of identifying candidates for genericity.

cliffblob wrote:
Better late than never?Yes!
cliffblob wrote:
...The answer I found to ID unnecessary casts was, using Eclipse IDE, In compiler error and warning preferences to warn on unnecessary casts.Thanks for pointing IDEs out. I just opened IntelliJ, and going back to at least version 7.04 (maybe earlier) they have an inspection for "Redundant type cast".
cliffblob wrote:
I would still be interested to know if there is a way to identify casts in general in your source, perhaps now four years later there is a way?The only solutions that I can think of are either a complicated regex search, or you must use some tool like an IDE that understand Java syntax and can determine if a cast is happening.

Help needed in data type casting

I have a java program which will receive data and its type in the String format. During program execution, the data in the String data has to be converted into the respective data type and assigned to a variable of that data type so that it could be used in the program. Programmer may not know the type of data that the value has to be converted into.
I really got struck up with this. This is a RMI application and one process node is sending the data to another node in the String format and the type of data it should get converted into so that it can be converted into the respective type and used for computation.
Can you understand what I am asking for ....if you can pls help and it is highly appreciated

I dont know whether i ahve expressed it correctly
look at this code
dataPacket sendtoNode = send.senDatatoNode(inputReq);
String recnodnum = sendtoNode.nodeNum;
String recvarnum = sendtoNode.varNum;
String recvartype = sendtoNode.dataType;
String recvalvalue = sendtoNode.dataVal;
int num; int type;
double result;
// here in this case the result variable type is double
if (recvartype.equals("int")){
 type = 1;
 result = Integer.parseInt(recvalvalue); will pose problem
 else
 if (recvartype.equals("double")){
 type = 2;
 result = Double.parseDouble(recvalvalue);
 else
 if(recvartype.equals("float")){
 type =3;
 result = Float.parseFloat(recvalvalue); will pose problem
 else
 if(recvartype.equals("Boolean")){
 if ((recvalvalue.equals("true")) || (recvalvalue.equals("TRUE")))
 type = 4;
 result = Boolean.parseBoolean(recvalvalue); will pose problem
 else
 if(recvartype.equals("char")){
 type = 5;
 result = (char)recvalvalue; will pose problem
else
if(recvartype.equals("String")){
 type = 6;
 result = recvalvalue; will pose problem
 else
 if(recvartype.equals("byte")){
 type = 7;
 result = Byte.parseByte(recvalvalue); will pose problem
 else
 if(recvartype.equals("long")){
 type = 8;
 result = Long.parseLong(recvalvalue); will pose problem
 else
 if(recvartype.equals("short")){
 type = 9;
 result = Short.parseShort(recvalvalue); will pose problem
 //forvarval varvalue = new forvarval();
 //varvalue.forvarval(recvartype, recvalvalue);
// this has to be done after sorting the problem of type casting string result = recvalvalue;
//result = value; //<this will surely give me a problem as i m assigning string to double>??
send.host(result);
System.out.println("result received and the result is " +recvalvalue );
now i need to assign the converted string in to a variable and use in the compuation ..thts where the challenge n not in teh conversion process...

Get / Cast a Java Object

Does anybody know how to get (or Cast) a Java Object returned from a Java method call ?
Example:
<cfset someList = object1.method1(someString, JavaCast("float",someNumber),...)>
This method returns a list of Java object of type "Object2". ie. it returns List<Object2>
Now I attempted to loop thru each objects from the returned list, and invoke some method on them, using code similar to below,
<cfset var="#someList[index]#"/>
but ColdFusion does not seem to understand the object "var" as Java "Object2". Is there any way I can cast the "var" to "Object2"?
Thanks in advance.
Xiaoling

"var" is a reserved keyword! You can initialize variables with "var" in the beginning of a component, but do not use it as a variables name:
<cfset var someVar = "#someList[index]#">

Type cast exception

Hi Guys,
I am pretty new at generics and have started reading all material available online. Shown below is the API that I am using
package api;
public interface CS<C extends MyConfig> extends S {
package api;
public interface MyConfig {
package api;
public interface MySession {
 public <C extends MyConfig, T extends ResourceContainer<? extends C>>
 T createContainer(CS<C> aPredefinedConfig);
package api;
public interface NC extends ResourceContainer<NCC> {
package api;
public interface NCC extends MyConfig {
package api;
import java.io.Serializable;
public interface ResourceContainer <T extends MyConfig> extends Serializable {
package api;
public interface S {
 public abstract boolean equals(Object other);
 public abstract int hashCode();
 public abstract String toString();
}And below is my implementation
package impl;
import api.NC;
public class NCImpl implements NC {
package impl;
import api.CS;
import api.MyConfig;
import api.MySession;
import api.ResourceContainer;
public class MySessionImpl implements MySession {
 public <C extends MyConfig, T extends ResourceContainer<? extends C>> T createContainer(
 CS<C> predefinedConfig) {
 NCImpl ncimpl = new NCImpl();
 return ncimpl; //Error Type mismatch: cannot convert from NCImpl to T
}As shown above I get error at line 'return ncimpl' But NCImpl implements the NC which extends ResourceContainer<NCC> so shouldn't it be capable of Type casting to T or I am missing something.
Thanks a lot for your response in advance

continuation of stack trace .................
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Compilation failure
/home/abhayani/workarea/eclipse/workspace/workspace-2.x/GenericsTest/impl/src/main/java/impl/MySessionImpl.java:[16,13] inconvertible types
found : impl.NCImpl
required: T
/home/abhayani/workarea/eclipse/workspace/workspace-2.x/GenericsTest/impl/src/main/java/impl/MySessionImpl.java:[16,13] inconvertible types
found : impl.NCImpl
required: T
[INFO] ------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.BuildFailureException: Compilation failure
/home/abhayani/workarea/eclipse/workspace/workspace-2.x/GenericsTest/impl/src/main/java/impl/MySessionImpl.java:[16,13] inconvertible types
found : impl.NCImpl
required: T
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:579)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:499)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:478)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:330)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:291)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:142)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:129)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:287)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.CompilationFailureException: Compilation failure
/home/abhayani/workarea/eclipse/workspace/workspace-2.x/GenericsTest/impl/src/main/java/impl/MySessionImpl.java:[16,13] inconvertible types
found : impl.NCImpl
required: T
at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:516)
at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:114)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:451)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:558)
... 16 more
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 5 seconds
[INFO] Finished at: Thu Feb 12 10:39:43 IST 2009
[INFO] Final Memory: 14M/81M
[INFO] ------------------------------------------------------------------------
[abhayani@localhost GenericsTest]$

Type Casting Exception

I have an attribute CategoryId in my VO of type oracle.jbo.domain.Number. I am trying to use the expression of Boolean item in JHS as #{row.CategoryId != 4}
Here is the generated JSF code:
 <af:column id="s141NewItem3Col" noWrap="true" width="100"
 rowHeader="false">
 <f:facet name="header">
 <af:outputLabel value="CAtIDDeq4" showRequired="false"
 id="ol18"/>
 </f:facet>
 <af:inputText id="s141NewItem3"
 value="#{row.CategoryId != 4}"
 label="CAtIDDeq4" required="false"
 readOnly="#{((pageFlowScope.ContractRightCategoriesTable.newRow) and (!(jhsUserRoles['RM, ADMIN, AllButTitl, AllButAdmn']))) or ((!pageFlowScope.ContractRightCategoriesTable.newRow) and (!(jhsUserRoles['RM, ADMIN, AllButTitl, AllButAdmn'])))}"></af:inputText>
 </af:column>I am getting the run time exception as "Can not convert 4 of type class oracle.jbo.domain.Number to class java.lang.Long"
I am wondering how the row.CategoryId is treated as Long?. PLease advise. Also, will I be able to use type casting expressions in J Headstart/JSF Expression Language?
Thanks, Pradeep

I am trying to set disabled property of an item SubCategory dynamically based on CategoryId value. I guess the transient attribute will not work for newly created records as the transient attribute will be null for newly created records before save is performed. However, the expression #{row.bindings.CategoryId.attributeValue.value== 4 ? false : true} is working fine. row.bindings.CategoryId.attributeValue seem to be returning Long and, row.bindings.CategoryId.attributeValue.value might be returning a Number.

Type casting for properties accessed in COM Object

I have a com object that I need to access which provides my a
list of addresses in an Array. The object give me a property that
has a count for the number of addresses and then I have a loop that
calls the property which contains the address details to get each
individual address each time passing to the property the INDEX
value on the loop.
This errors out each time.
The error I get is
Error casting an object of type to an incompatible type.
This usually indicates a programming error in Java, although it
could also mean you have tried to use a foreign object in a
different way than it was designed.
It appears the the variable type of the index is not
compatible with the property of the component(which is an int).
IS there some way to type cast the variable used as the index
for CFLOOP to that of an INT?

You can try to use the JavaCast("int", myValue) function. It
works great for Java objects, but I'm not sure how well it will
work for COM. Worth a try, I guess.
In your case it would be something like:
<cfobject type="COM" context="INPROC" action="create"
name="MR" class="DLLNAME">
<cfloop from="1" to="#AddressCount#" index="i">
<cfset VDname = mr.vdsname(JavaCast("int", i))>
<cfset VDaddress = mr.vdsaddress(JavaCast("int", i))#>
<cfset VDXML = mr.VDSXML(JavaCast("int", i))>
</cfloop>

Type casting problem in the JSP

Hi,
I am type casting an Object variable to a interface Variable. I am not getting any error if i have the same code in the servlet but i am getting ClassCast Exception if i have the same code in the Scriplets part of the JSP.
The code is as follows
String strKey = " SomeString";
Context context = new InitialContext();
java.lang.Object obj = null;
     obj = context.lookup(strKey);
     ContentBroker objCB = null;
     objCB = (ContentBroker)obj; // Error is happening here
ContentBroker is an inteface.
I have included the jar files of ContentBroker in the classpath.
Can anyone please tell me how to eliminate this error.?
thanks in advance,
Saravanan

In that case it's a classloader issue.
Since the object is bound in the context, I assume that you have made the class available to your server, and you have the class in WEB-INF/classes or in a jar inside WEB-INF/lib.
Since they're being loaded by two different classloaders, the classes are seen as different by the JVM, thus the ClassCastException.
Try removing the class from the web-app and let us know what happens.
BTW. Which servlet container are you using?

How to use Type Casting in JSF Expression Language

I have an attribute CategoryId in my VO of type oracle.jbo.domain.Number. I am trying to use the expression of Boolean item in JSF as #{row.CategoryId != 4}
Here is the JSF code:
 <af:column id="s141NewItem3Col" noWrap="true" width="100"
 rowHeader="false">
 <f:facet name="header">
 <af:outputLabel value="CAtIDDeq4" showRequired="false"
 id="ol18"/>
 </f:facet>
 <af:inputText id="s141NewItem3"
 value="#{row.CategoryId != 4}"
 label="CAtIDDeq4" required="false"
 readOnly="#{((pageFlowScope.ContractRightCategoriesTable.newRow) and (!(jhsUserRoles['RM, ADMIN, AllButTitl, AllButAdmn']))) or ((!pageFlowScope.ContractRightCategoriesTable.newRow) and (!(jhsUserRoles['RM, ADMIN, AllButTitl, AllButAdmn'])))}"></af:inputText>
 </af:column>I am getting the run time exception as "Can not convert 4 of type class oracle.jbo.domain.Number to class java.lang.Long".
I am wondering how the row.CategoryId is treated as Long?. PLease advise. Also, will I be able to use type casting expressions in JSF Expression Language?
Thanks, Pradeep

use attributeValue
Try *#{row.bindings.CategoryId.attributeValue != 4}* ?
Check this thread for details which discusses about the same:
El expression to disable or enable
Thanks,
Navaneeth

Type casting in JAX-RPC

Hello
I was trying to do a JAX-RPC application, and I had some problems with type casting. My application worked fine with primitive types, vectors of primitive types, and beans with primitive type properties. But it didn't work with vectors of beans, or ArrayList's of beans... It couldn't deserialize the result on client side... Can anyone help?
The Java Web Services Tutorial says that JAX-RPC supports beans and vectors, but I had the impression that this is not a "recursive" support, like "beans with vectors" or "vectors of beans"... Does it make sense?
By the way, I was using a DII client...
Thanks,
Alexandre Murakami

Hello!
Thanks for the reply! I can't put the code of my application here (because it's quite big and it's from work)... But I followed the dii client example from the Web Services Tutorial...
I'm trying to do a kind of a general client... The parameters are the URL of the service, the name of the operation, a list of parameters and the return type class.. And it takes the rest of the service information from the WSDL file... About the return type, I take the QName of the return type from the WSDL:
<message>
<part name="result" type="...">...
then I call the call.setReturnType(QName, Class) method. The return type was an array of a very simple bean, something like:
class Person {
String name;
int age;
public String getName() {...}
public void setName(...) {...}
public int getAge() {...}
public void setAge(...) {...}
I don't know if the information I put here is enough... but anyway, thanks for the reply!
Alexandre Murakami

Object array type casting?

Hi. I still can't get the hang of array type casting. Is it possible to type caste an array of objects? I tried the following
LabelledPanel[] comp = (LabelledPanel[])(content.getComponents());
in my program and I got the ClassCastException.
Exception occurred during event dispatching:
java.lang.ClassCastException: [Ljava.awt.Component;
LabelledPanel is a descendent of JPanel and getComponents() supposed to return Component[]

java does support casting with arrays. The following code will work:
String [] strings = new String[] { "1", "2" };
Comparable [] comps = (Comparable[])strings;
Object [] objects = (Object [])strings;That is, you can cast following the normal rules of assignment. You are having problems because your casting violates the normal rules of assignment- you're trying to cast a type into a differnt type that it does not extend or implement.
the toArray() in the Collections API really has nothing to do with casting. That method converts the current Collection into an array of the same type. Since all arrays extend java.lang.Object, it returns the new array as an Object, which you then cast into the specific type.
You may want to read the language guidlines on casting if you are having problems with it:
http://java.sun.com/docs/books/jls/second_edition/html/jIX.fm.html
you can also look at the documenation for Class.isAssignableFrom , which explains casting more briefly.

Type cast of BigInteger to Int

Hi All,
I am working on Email Web Service with Web dynpro.
I am getting an error in type casting BigInterger(which was declared in WSDL) to Int. Java is not recognizing this BigInteger. Can any one help me??
Regards,
Theja

Thejaswi,
Where exactly this happens?
I mean, if you can control this part of code why not to do:
BigInteger bigInt = <...>;
int int = bigInt.intValue();
VS

Type casting in Java

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