Invoking methods extracted from a string?!?

Hi everybody. I hope the subject is not confusing. What I'm really looking for is some Perl-like behaviour in Java. In Perl its possible to execute subroutines (basicly methods) extracted from a string ("&sub()"). Is there anything similar in Java?
What I would like to do is to process a string and if it has a method (object.getTime()), the method will be called and the return value stored in its place.
Please let me know if more explanation is needed.
Thanks in advance for all the help!
Leo.

I use a language called MUMPS where you can do that as well - execute strings as commands etc. I don't know much about Reflection but it looks like you can get method (Objects) from strings and execute them as well ...

Similar Messages

How to extract from a string ?

Hello , I have this string and I need to extract 4 parts (in bold) from the string , my string is :
'(invoice) dear client : tom cruise you Buy *408* from MENA.CA @ *6.93* 01/10/09 watheeqa'
What is the best technique to do that?
Thanks

Hi,
oais wrote:
Hello , I have this string and I need to extract 4 parts (in bold) from the string , my string is :
'(invoice) dear client : tom cruise you Buy *408* from MENA.CA @ *6.93* 01/10/09 watheeqa'
What is the best technique to do that?
ThanksThat depends on how you know the 4 parts are what you showed, and not
'(invoice) dear client: tom cruise you Buy 408 from MENA.CA @ 6.93 01/10/09 watheeqa'
or
'(invoice) dear client: tom cruise you Buy 408 from MENA.CA @ 6.93 01/10/09 watheeqa?'
or
'(invoice) dear client: tom cruise you Buy 408 from MENA.CA @ 6.93 01/10/09 watheeqa'
Will there always be exactly four parts you need to pick?

Invoking method with reflection - with String[] params

Hi there,
I have a method that I need to call with reflection. This method has one parameter
public void setArgs(String args[])
I'm trying to invoke it by reflection. I tryied this but didn't work:
Class[] parameterArgs = {String[].class};
Method mCallArgs = objClasseChiamata.getClass().getMethod("setArgs",parameterArgs);
Object[] nomeArgs = new Object[]{"Luca","Alessio"};
//I try too:
//String[] nomeArgs = new String[]{"Luca","Alessio"};
mCallArgs.invoke(objClasseChiamata ,nomeArgs);
It compile ok,
but in Runtime I find this error:
java.lang.IllegalArgumentException
java.lang.Throwable()
java.lang.Exception()
java.lang.RuntimeException()
java.lang.IllegalArgumentException()
java.lang.Object java.lang.reflect.Method.invoke(java.lang.Object, java.lang.Object [])
void reflection.TestReflection.main(java.lang.String [])
Thank you,
Alessio

The thing that goes in the Object[] is the paramaters. The parameter is one String[], not two Strings:
Object[] nomeArgs = { new String[] {"Luca", "Alessio"} };
mCallArgs.invoke(objClasseChiamata ,nomeArgs);
// or
mCallArgs.invoke(objClasseChiamata, new Object[] { new String[] {"Luca", "Alessio"} });Note that there's no reason to use "new Object" when you're initializing a named array reference (just like you initialized the Class[] above).

Invoke method dynamically based on string name.

In my code i have some 50 odd if else condition:
if(command.equals("abc"))
//call abc method
abc();
else if(command.equals("xyz"))
// call xyz();
and so on........
now based on command string i need to call a method whose name is identical to command string.
I have used reflection to do this and it works. But just need to know ,
is there any other approach available?
Also, it is better to use reflection or just write 50 if else statements and call each function.
TIA,
Sachin

hey i asked the same question a little while ago and got some
very good feedback at this thread
http://forum.java.sun.com/thread.jspa?threadID=646255
i had written some test code but i cant find it.
you will be looking for this kind of stuff though
(this isnt intelligible code)
Object o = Class.forName("hto");
Field[] fields = ht.getClass().getDeclaredFields();
Class class1 = ( fields[1].getType() );
Class class2 = Class.forName("MyClassName");
Class[] param = { value.getClass() };
Object[] invokeParam = { value };
Class[] prim = { Class.forName("HackThis") };
Method method = ht.getClass().getMethod("set" + var, param);
method.invoke(ht, invokeParam);

How to extract an integer or a float value from a String of characters

Hi i have a problem getting to a float value within a string of characters..
for instance the string is
"numberItem xxxxxxxxx 700.0" (each x is a space..the forum wouldnt let me put normal spaces for some reason)
how do i store 700.0 in a float variable
remember the string is obtained from an inputfile
so far i got the program to store the inputfile data line by line in a String array..i tried tokenizing the string to get to the the float value but since i have mulitple spaces within my string, the token method only gets "numberItem" from the above String
This is all i have so far:
String c;
String Array[] =new String[g]; (i used a while loop to obtain g(the nubmer of lines in the file))
while((c=(cr.readLine()))!=null)
Array[coun]=c;
it would be reallllllllllllllllllllllllllllllllllllllly easy if there was a predefined method to extract numeric values from a string in java..
Edited by: badmash on Feb 18, 2009 5:50 PM
Edited by: badmash on Feb 18, 2009 5:50 PM
Edited by: badmash on Feb 18, 2009 5:55 PM

badmash wrote:
Hi i have a problem getting to a float value within a string of characters..
for instance the string is
"numberItem xxxxxxxxx 700.0" (each x is a space..the forum wouldnt let me put normal spaces for some reason)
with the space included
how do i store 700.0 in a float variable
remember the string is obtained from an inputfile
so far i got the program to store the inputfile data line by line in a String array..i tried tokenizing the string to get to the the float value but since i have mulitple spaces within my string, the token method only gets "numberItem" from the above StringHuh?
Not true.
Anyway why not use string split, split on spaces and grab the last element (which by the format you posted would be your 700.0)
Then there is the Float.parseFloat method.
It is easy.
And another thing why not use a List of Strings if you want to store each line? (And why did you post that code which doesn't really have anything to do with your problem?) Also in future please use the code formatting tags when posting code. Select the code you are posting in the message box and click the CODE button.

Extract int from a string

Hi,
I am curious if there is an easy way to extract an int value from a String.
For example, "Rb23" to get 23. The length of the part in front of the integer is variable.
Thanks

this seems to work:
public int extract(String s) {
     String result = "";
     char c[] = s.toCharArray();
     int j = c.length-1;
     if (!Character.isDigit(c[j])) {
          return 0;
     do {
          result+=c[j--];
     } while (j > 0 && Character.isDigit(c[j]));
     return Integer.parseInt(new StringBuffer(result).reverse().toString());
}it will return 0 if no numbers are found at the end of the string

Java method call from c passing string more info

I am trying to call a java method from c passing a String as an argument.
my C code is as follows.
//Initalise jstring and class (to recieve String)
jstring textp;
jclass texts = (*env)->GetObjectClass(env, obj);
jmethodID text = (*env)->GetMethodID(env, texts, "texture", "([Ljava/lang/String;)V");
//Create a new jstring from the char* texturePath (in textures)
//call the java method with the jstring
textp = (*env)->NewStringUTF(env,ret.textures->texturePath);
(*env)->CallVoidMethod(env, obj, text,textp);
//java code
// texture which recieves a string
public void texture(String texturePath){
The error I get is as follows:
SIGSEGV 11 segmentation violation
si_signo [11]: SEGV
si_errno [0]:
si_code [1]: SEGV_MAPERR [addr: 0xc]
stackpointer=FFBED790
"Screen Updater" (TID:0x4f9060, sys_thread_t:0x4f8f98, state:CW, thread_t: t@11, threadID:0xf2d31d78, stack_bottom:0xf2d32000, stack_size:0x20000) prio=4
[1] java.lang.Object.wait(Object.java:424)
[2] sun.awt.ScreenUpdater.nextEntry(ScreenUpdater.java:78)
[3] sun.awt.ScreenUpdater.run(ScreenUpdater.java:98)
"AWT-Motif" (TID:0x40be50, sys_thread_t:0x40bd88, state:R, thread_t: t@10, threadID:0xf2d71d78, stack_bottom:0xf2d72000, stack_size:0x20000) prio=5
[1] sun.awt.motif.MToolkit.run(Native Method)
[2] java.lang.Thread.run(Thread.java:479)
"SunToolkit.PostEventQueue-0" (TID:0x431950, sys_thread_t:0x431888, state:CW, thread_t: t@9, threadID:0xf2e71d78, stack_bottom:0xf2e72000, stack_size:0x20000) prio=5
[1] java.lang.Object.wait(Object.java:424)
[2] sun.awt.PostEventQueue.run(SunToolkit.java:407)
"AWT-EventQueue-0" (TID:0x430ea8, sys_thread_t:0x430de0, state:CW, thread_t: t@8, threadID:0xf3071d78, stack_bottom:0xf3072000, stack_size:0x20000) prio=6
[1] java.lang.Object.wait(Object.java:424)
[2] java.awt.EventQueue.getNextEvent(EventQueue.java:212)
[3] java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:100)
[4] java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:91)
[5] java.awt.EventDispatchThread.run(EventDispatchThread.java:83)
Exiting Thread (sys_thread_t:0xff343db0) : no stack
"Finalizer" (TID:0x154e98, sys_thread_t:0x154dd0, state:CW, thread_t: t@6, threadID:0xfe391d78, stack_bottom:0xfe392000, stack_size:0x20000) prio=8
[1] java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:146)
[2] java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:168)
[3] java.lang.ref.Finalizer$FinalizerWorker$FinalizerThread.run(Finalizer.java:124)
"Reference Handler" (TID:0x1506a0, sys_thread_t:0x1505d8, state:CW, thread_t: t@5, threadID:0xfe3c1d78, stack_bottom:0xfe3c2000, stack_size:0x20000) prio=10
[1] java.lang.Object.wait(Object.java:424)
[2] java.lang.ref.Reference$ReferenceHandler.run(Reference.java:130)
"Signal dispatcher" (TID:0x13d180, sys_thread_t:0x13d0b8, state:MW, thread_t: t@4, threadID:0xfe3f1d78, stack_bottom:0xfe3f2000, stack_size:0x20000) prio=10
"main" (TID:0x38918, sys_thread_t:0x38850, state:R, thread_t: t@1, threadID:0x25228, stack_bottom:0xffbf0000, stack_size:0x800000) prio=5 *current thread*
[1] loader.Callbacks.nativeMethod(Native Method)
[2] loader.Callbacks.main(Callbacks.java:184)
[3] graphics.GR_MakeTrack.init(GR_MakeTrack.java:60)
[4] graphics.GR_MakeTrack.main2(GR_MakeTrack.java:49)
[5] graphics.GR_MakeTrack.main(GR_MakeTrack.java:41)
[6] control.GE_main.GE_main1(GE_main.java:87)
[7] control.GE_main.main(GE_main.java:66)
gmake: *** [run] Abort (core dumped)

I am trying to call a java method from c passing a
String as an argument.
my C code is as follows.
//Initalise jstring and class (to recieve String)
jstring textp;
jclass texts = (*env)->GetObjectClass(env, obj);
jmethodID text = (*env)->GetMethodID(env, texts,
"texture", "([Ljava/lang/String;)V");
Hi Pete,
your problem is that the method texture you are trying to find does not exist. If you look carefully at your declaration of the method signature in the GetMethodID call you will see "([Ljava/lang/String;)V" which is trying to find a method that accepts a String array as its parameter. Remove the [ from the method signature and it should work ok. You might want to test text (jmethodID) for NULL or 0 before trying to call it as well.

In the NI Library VI: Extract Numbers, the string control is automatically loaded each time the VI is opened with "Counting to five: one 2 three 4.0 five. Where is this string data coming from?

Even after deleting the string "Counting to five: one 2 three 4. five." from the string control and replacing it with another string the original string returns after the VI is saved then reopened. Where is this string data coming from? I've attached a copy of the library function. I've been able in my application to get around the problem by replacing the string control with a string constant. But I'm still curious as to what's going on.
Thanks,
Chuck
Solved!
Go to Solution.
Attachments:
Extract Numbers Test.vi ‏9 KB

Chuck,
String control has been set to default with the string you are seeing. To change this, enter the new string, right click the control and select
Data Operations>>Make Current Value Default
Now save your vi.

Invoking methods in C++ from Java

I'm invoking the Java Virtual Machine from my C++ program like is described here: http://java.sun.com/docs/books/tutorial/native1.1/invoking/invo.html
So, I run my C++ program (let's call it C), C invokes the JVM and starts a Java program (let's call it J). C can now invoke methods in J. Now I want J to invoke a method in C. Is this possible?

Yes it is.
However your C code that you want to invoke from java must be defined as "native" - that is, it is defined as the implementation for java methods that are declared native.
The possibly most confusing part is where to put the C code and how to make the java-C linkage.
o You can put the C code in a DLL, and use a "loadLibrary" call to make it available.
o Alternatively, and perhaps more likely, your original C/C++program can make "registerNative" calls to the JVM to identify to it the native implementations.

Invoke a method by getting method name from properties object

HI ,
I am storing method names in a properties file . Can any one tell me , how can I invoke those methods ?? Please Urgent.
Here is the sample program what I am trying to do . Please tell me how to invoke method which is represented by the String "methodTobeInvoked" in the below program.
public class HelloWorld {
     private String name="meena";
     public String getName() {
          return name;
     public void setName(String name) {
          this.name = name;
     public static void main(String[] args) {
          try {
               Properties props=new Properties();
               props.setProperty("method", "getName()");
          String methodTobeInvoked= props.getProperty("method");
          }catch (Exception ioe) {
               System.err.println(ioe.getMessage());
Thanks!!!

meenaalenoor wrote:
I am storing method names in a properties file . Can any one tell me , how can I invoke those methods?
Here is the sample program what I am trying to do.
Please tell me how to invoke method which is represented by the String "methodTobeInvoked" in the below program.
public class HelloWorld {
     private String name="meena";
     public String getName() {
          return name;
     public void setName(String name) {
          this.name = name;
     public static void main(String[] args) {
          try {
               Properties props=new Properties();
               props.setProperty("method", "getName()");
          String methodTobeInvoked= props.getProperty("method");
          }catch (Exception ioe) {
               System.err.println(ioe.getMessage());
}Have you looked at [java.lang.reflect|http://java.sun.com/j2se/1.5.0/docs/api/java/lang/reflect/package-summary.html] ?

Extracting the partial string from the string in oracle

Hello Friends,
I have a string like this
var str = '/G/CNH/CNHCornerstone/currentCode/data/Working/Images/ModelImages/png/7402203E-607D-E111-9CA5-005056875BD6.png'
I want to extract only 7402203E-607D-E111-9CA5-005056875BD6 from the string .
Please let me know how to implement this ..
thanks/kumar
Edited by: kumar73 on Apr 10, 2012 12:34 PM

hope this works
set serveroutput on
declare
str1 varchar(4000);
str2 varchar(4000);
begin
str1 := '/G/CNH/CNHCornerstone/currentCode/data/Working/Images/ModelImages/png/7402203E-607D-E111-9CA5-005056875BD6.png';
dbms_output.put_line('string 1 : ' || str1);
str2 := substr(str1,71);
dbms_output.put_line('string 2 : '||str2);
end;
output
string 1 : /G/CNH/CNHCornerstone/currentCode/data/Working/Images/ModelImages/png/7402203E-607D-E111-9CA5-005056875BD6.png
string 2 : 7402203E-607D-E111-9CA5-005056875BD6.png
PL/SQL procedure successfully completed

Data extraction from string

I'm trying to search a particular value in a string file. The string contains many parameters followed by their values and units. I want to identify and extract, as a number, the value of a particular parameter. The program will basically ask the user to type in (or select from a list of given) parameters in a dialogue box. Then it should display the value of the parameter.
The string I'm trying to work with, is of the form:-
SensorOneInMM,34585
BatteryVoltageInmV,19761
BattTemp1InC,20
CliffDistanceLeftInMM,60
CliffDistanceRightInMM,60
RightSensor,0
LeftSensor,0
CurrentInmAforMotor, 789
TestingCurrentInmA, 123
Temp1InC,28
Temp2InC,28
BaseCurrentInmA,1342
ChargeInmV,218
CurrentInmA,9999
NotConnected3,0
Now, for example the value I want to read is the one in Blue color. But the expression, "CurrentInmA" appears several times, in the string. How can I identify the value of the parameter in Blue color??
Thanks for helping out an amateur!!!
Cheers.

Rajat
I think you want to extract the value from specific string..
you can get number of post releted to your question...few are follow
Post 1
Post2
also see attached vi which specific to your problem..
Attachments:
Extract frm string.png ‏21 KB

Extracting data from a string of characters

Hi,
I have a problem that I am having difficulty solving, if anyone has any bright ideas it would be a great help.
I have a description field in one of my tables and the description would read something like
my website can be found at www.mywebsite.com, and it is great
I want to be able to extract the web address from this sentance, so the result would be
www.mywebsite.com
I can do this specific for one sentance but I can't find a way to do it for many different sentances.
cheers in advance

If you're using 10g, you probably want to do something with regular expressions:
SQL> with strings as (
2    select
3              'my website can be found at www.mywebsite.com, and it is great' str
4    from
5              dual
6    union all
7    select
8              'my website can be found at WWW.myWebSite.com, and it is great'
9    from
10              dual
11    union all
12    select
13              'our web address is www.mywebsite.co.uk' str
14    from
15              dual
16    union all
17    select
18              'http://www.mywebsite.com/great'
19    from
20              dual)
21 select
22            s.str
23          , regexp_substr(s.str, 'www\.[a-z0-9-\.?]*', 1, 1, 'i') extr
24 from
25            strings s
26 /
STR                                                           EXTR
my website can be found at www.mywebsite.com, and it is great www.mywebsite.com
my website can be found at WWW.myWebSite.com, and it is great WWW.myWebSite.com
our web address is www.mywebsite.co.uk                        www.mywebsite.co.uk
http://www.mywebsite.com/great                                www.mywebsite.comYou'd be better asking this kind of thing on the PL/SQL (and definitely better asking someone other than me anything further about regular expressions!)

Extracting method names from JNI probes

Hello.
I would like to use the Call* probes from the hotspot_jni provider. These probes provide as argument a "method id". My question is how I can extract, for instance, the method name from this ID. I saw that JNI provides a method "GetMethodName" but being a dtrace novice, I am unsure how to obtain a handle to the JNI api from within dtrace.
Any hint would be greatly appreciated.
Best wishes,
Eric

Actually, it can be done. Otherwise, how do you think debugger shows variables and formal parameters?
You should compile your aplication with debuginng information (for details see tools doc). Then you have 3 options:
1) run application under debugger and use JVMDI to get everything you want;
2) use bytecode libraries (BCEL, CGLib etc) to read class file and fetch required information through their API
3) write your own class file parser based on class file format described in Java Virtual Machine Specification
First way is quite complex and is definitely not for "production use".
Second way is the best in case you have time limitations, but size of your application will be increased because of thrid-party libraries.
Thrid way is the best if you have application size restrictions and have enough time to write simple class file parser to fetch that specific information (1-2 days depending on your experience).
Have fun ;)

Extract words from a string

select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
PL/SQL Release 11.1.0.7.0 - Production
CORE    11.1.0.7.0    Production
TNS for Linux: Version 11.1.0.7.0 - Production
NLSRTL Version 11.1.0.7.0 - ProductionI want to extract xyz_xyz,abc_abc words from the string ' select * from TEMP_TABLE where trunc(xyz_xyz) = ''xyz'' and trunc(abc_abc) = ''abc'') '
i have tried with this query...
select regexp_substr('select * from TEMP_TABLE where trunc(xyz_xyz) = ''xyz'' and trunc(abc_abc) = ''abc'')', 'trunc[^'''']+''') from dual
can some one help me on this?
Thanks,
Mike

Hi, Mike,
Mike wrote:
I apologize for this..
create table TEMP_TABLE ( col1 varchar2(10),col2 varchar2(10));
insert into TEMP_TABLE values('   xyz   ','abc      ');
insert into TEMP_TABLE values('   xyzxyz ','abcabc    ');
insert into TEMP_TABLE values('   xyz123 ','abc546 ');
insert into TEMP_TABLE values('xyz','abc');
commit
select * from TEMP_TABLE where trim(col1) ='xyz' and trim(col2) ='abc'
desired output
col1,col2
So the correct output is one row, containing these 9 characters
col1,col2which do not appear in the table. is that right?
How is that output related to the data that is in the table? Do you want that output to appear if there are any rows where TRIM (col1) = 'xyz' and TRIM (col2) = 'abc' (for example, either of these two rows from you sample data:
insert into TEMP_TABLE values('   xyz   ','abc      ');
insert into TEMP_TABLE values('xyz','abc');), and would you want the result set to contain no rows if the table contained no row like that?
If so,
SELECT DISTINCT
     'col1,col2'     AS desired_output
FROM     temp_table
WHERE     TRIM (col1)     = 'xyz'
AND     TRIM (col2)     = 'abc'
;I hope this answers your question.
I have a feeling that it doesn't, or perhaps you have more than one question, since this your earlier messages seemed to have something to do with locating text that was surrounded by single-quotes, and the sample data you posted doesn't contain any single-quotes.

Invoking methods extracted from a string?!?

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