Instanceof vs string methods.

Hi
I would like to know if 'instanceof' check is faster than
the String's substr() method, in terms of better performance.
Also is there a built in java utility program that can be run aganist any java programs to get statistics about the performance.
Thanks in advance.

Hi guys,
I totally understand that instanceof and String's
methods are no way related to each other.
I actually was thinking of two different ways of
solving a problem, where in at one place, I could use
either of the above.
Thus all I needed to know was if there would be an
extra overhead involved using each of the above.
Well thanks for all your Compliments you gave in the
previous replies to this question.
Nothing to take personal.
Have a great day.
Why does everyone think that instanceof is slow?
Comparing strings is crazy slow if you think about it as you have to go char by char and compare each slowly.
Every class maintains a list of all interfaces that it implements, even the inherited ones if an implemented interface extends another. So doing instanceof while looking for interfaces is wicked (yes, wicked) fast. While you may have to go up a few levels of inheritance to see if a class extends another class, it's still faster then comparing strings, or at least no slower, being N time, where N is the max number of classes that you inherit from.
Look at it this way.
new Object() instanceof Component; // one check, since object has no parents.
new ArrayList() instanceof Component; // max 7 checks, since ArrayList extends abstractlist extends abstractcollection extends object, and implements list, cloneable, serializable, though the runtime could realise that component is a CLASS and not an interface and skip the interface checks.
new ArrayList() instanceof List; // max 3 checks since all interfaces are stored with the class object.doing an instanceof should be very, very fast. If it's not then blame the vm.

Similar Messages

"Import string" method not supported in LabVIEW 7.1

We have made an application that support multi-language (English, French, etc.). In LabVIEW 6.1, we used the "import string" VI method to support this option. The method was executed just before to open front panel. The code was based on this example found in NI Developer Zone:
Translation/Localization Tools in LabVIEW
(http://sine.ni.com/apps/we/niepd_web_display.display_epd4?...
But surprise in version 7.1, this method can't be loaded without the diagram block. So the built application doesn't support it! It works only in the development interface. Why this change?
If someone has an idea to solve this, let me know.

If you build that example into an EXE under LabVIEW 7.1, it should work fine as long as you add the non top-level VIs as Dynamic VIs and add the language files as Support Files when you create the executable, making sure to specify in "Custom Destinations" that you want the string files to end up in the same directory as the EXE.
Your point about the method requiring the block diagram is correct, according to the help for the method. However, I think the diagrams will be available to the run-time engine as long as you haven't purposefully removed them prior to creating the EXE in the manner described above. Maybe someone else can chime in on this point, because I know the App Builder changes a lot with every new major LabVIEW version (and sometimes, with minor versions too!).
In any case, I just did a test where I downloaded the example you referenced, created a .BLD file as I indicated above, and got a successful executable that was able to use the Import VI Strings method to load the desired language at run-time.
Regards,
John

Import & Export Strings method

Hi,
I have a multilanguage application. I have used export & import
strings methods. I have one .txt file for each language but when I
modify something in my vi I must export all again and then modify the
tags again for each language file... Is there a way that I can modify
my vi and I don't have to export all again?
Thanks,
ToNi.

As far as i know you need to export strings again only if you have made any changes on front panel.
exported file is nothing but a xml file so that you can manually edit it instead of exporting everything again (helpfule if you have done very small changes on front panel)
Tushar Jambhekar
[email protected]
Jambhekar Automation Solutions
LabVIEW Consultancy, LabVIEW Training
Rent a LabVIEW Developer, My Blog

NullPointerException on String methods

All,
I am trying to get date values on the fly and add them to my sql statement. I have a DateWorker class that provides month, day of month and year.
When I use the class in another class, I get NullPointerException. These are just plain ol' String methods, why are they giving me problems. When I run the code on its won, it works fine.
Code:
package mybeans;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Calendar;
public class DateWorker {
public DateWorker dateWorker;
 public DateWorker(){
 dateWorker = new DateWorker()
 public static void main(String[] args){
 String m = dateWorker.getMonth();
 String dm = dateWorker.getDayOfMonth();
 String dw = dateWorker.getDayOfWeek();
 String y = dateWorker.getYear();
 System.out.println("day of week " + dw + " ");
 System.out.println("day of month" + dm + " ");
 System.out.println("month " + m + " ");
 System.out.println("year " + y + " ");
 //get a Calendar instance.
 private Calendar cal = Calendar.getInstance();
 //gets the current month
 public String getMonth(){
 int x = cal.get(Calendar.MONTH) + 1;
 String s = String.valueOf(x);
 return s;
 //gets the current day of month
 public String getDayOfMonth(){
 int x = cal.get(Calendar.DAY_OF_MONTH);
 String s = String.valueOf(x);
 return s;
 //gets the current day of week
 public String getDayOfWeek(){
 int x = cal.get(Calendar.DAY_OF_WEEK) -1;
 String s = String.valueOf(x);
 return s;
 //gets the current year
 public String getYear(){
 int x = cal.get(Calendar.YEAR);
 String s = String.valueOf(x);
 return s;
Edited by: ink86 on Oct 8, 2007 12:57 PM

package mybeans;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Calendar;
public class DateWorker {
 public static void main(String[] args){
 DateWorker dateWorker = new DateWorker();
 String m = dateWorker.getMonth();
 String dm = dateWorker.getDayOfMonth();
 String dw = dateWorker.getDayOfWeek();
 String y = dateWorker.getYear();
 System.out.println("day of week " + dw + " ");
 System.out.println("day of month" + dm + " ");
 System.out.println("month " + m + " ");
 System.out.println("year " + y + " ");
 //get a Calendar instance.
 Calendar cal = Calendar.getInstance();
 //gets the current month
 public String getMonth(){
 int x = cal.get(Calendar.MONTH) + 1;
 String s = String.valueOf(x);
 return s;
 //gets the current day of month
 public String getDayOfMonth(){
 int x = cal.get(Calendar.DAY_OF_MONTH);
 String s = String.valueOf(x);
 return s;
 //gets the current day of week
 public String getDayOfWeek(){
 int x = cal.get(Calendar.DAY_OF_WEEK) -1;
 String s = String.valueOf(x);
 return s;
 //gets the current year
 public String getYear(){
 int x = cal.get(Calendar.YEAR);
 String s = String.valueOf(x);
 return s;
 }

Urgent!!! Problem on the String method and File method

I would like to ask two questions:
(1) From the String method, it can use .equals() method to compare two strings whether two string exactly equal or not. But what method can i use to compare two strings see whether any words exists in the string?
(2) From the following code,
Java.io.File outFile = new java.io.File("TestProg.java");If i would like to use a variable (e.g. let the variable be name) instead of the filename "TestProg.java", do you know how to revise the above code??
If i write as following, is it correct???
Java.io.File outFile = new java.io.File(""+name+"");Please help!!!

1- To check whether a word (sunstring) exists in a longer string, you can use the following String method:
indexOf(substring) on the string that you are searching. If the word does not exist, -1 is returned.
2- yes you can provide a variable (of type string) in the constrcutor of File.

Regex or String methods

Hi
Im wondering how more experienced Java developers would approach this.
I have a parser which receives Strings according to the irc-protocol.
servername PRIVMSG #channel :Hello worldAlmost every message is defined by the second word in the String. So its easy to just do String.split(" ") ... check the messagetype and start working with the other elements. Of course things gets a bit out of hand with compareTo(), IndexOf(), Substring() ... and all the other String methods.
How would u use regex for this if u had to? I see this as exercise ... slower code, more work ... doesnt matter and its a plus learning more about regex.
Example ... the line above, how would u use regex to check the messagetype "privmsg" ... channel "#channel" and the messagepart after the ':' etc ...
many thanks in advance

I wouldn't use regex, but split indeed, since I'd
have very easy access to each part of the message.
Anyway, since you want to learn regex: why don't you
grab the Pattern API and read and try a little
yourself? Nothing teaches you better than finding out
yourself.Well yes regexes are nice easy and clean. And a wevy usefull if you learn them cos it gives you unlimited power of string manipulation.
But at a high cost.
It is verry important to make the right choice (regex or string methods) becouse it will decide how good your code looks and work.
If the pattern that need to be parsed is simple and cam be done using string methods (including string tokenizer) regex is not the way to go.
Normally when handling simple text patterns like above the string methods will perform about 5 times faster than regexes.
So my recomendation is.
If you are doing this for learning do it both ways and practice both regexes and string methods. Becouse in the industry you have know the both well.
If you are doing this for some sort of a project and performance is a significant quality factor you need to use string methods in this perticuler situation.
Above pattern can easilly broaken down using a combination of substring, index of and string tokenizer.

Why is String method called not Object method

In the below program ::
class Test
     public void callMethod(Object o)
          System.out.println("Object Method Called");
     public void callMethod(String s)
          System.out.println("String Method Called");
     public static void main(String[] args)
          Test t = new Test();
          t.callMethod(null);
}

In the below program ::
class Test
     public void callMethod(Object o)
          System.out.println("Object Method Called");
     public void callMethod(String s)
          System.out.println("String Method Called");
     public static void main(String[] args)
          Test t = new Test();
          t.callMethod(null);
}If more than one method could be called the most specific one is called. Since a String is an Object then the String one gets called.

Can I use to.String() method with NamedCache

Hi,
I have a distributed cache. Can I use to.String() method to print the contents of cache on the console. In my case it is not working..Do I neet to import anything?
NamedCache cache = CacheFactory.getCache("Test");
cache.put("hello", "world");
System.out.println(cache.toString());
Thanks,
Chaya

Hi Chaya,
Assuming that I understand your question correctly, each JVM has the same view of the cache if you're using a distributed (or optimistic, replicated, ...) cache. So when you add records from one JVM, they are visible to all the JVMs immediately (if you start up a new JVM, it will join the cluster and share the data as well).
So if you populate a named cache from JVM1, you can simply execute the display code (from my previously reply) in any JVM connected through Coherence, and it will display the entire contents of the logical named cache.
Jon Purdy
Tangosol, Inc.

String method indexOf

I have to show the number of occurances of a character in a string.
I chose the letter 'a' - here is my code, my problem is i only get one occurance, how do i show all indexes of 'a'?
thanks,
barb
// Java extension packages
import javax.swing.*;
public class IndexOf {
public static void main( String args[] )
String text ="This class is really hard \n" +
 "I'm glad I did well on the midterm \n" +
 "It took a long time.";
 String output1 = "'This class is really hard.\n" +
 "I'm glad I did well on the midterm.\n" +
 "It took a long time.'"+ "\n\n";
 int pos;
int count = 0;
pos = text.indexOf ('a');
while ( pos != -1)
 count++;
 pos = text.indexOf ('a', pos+1);
// test indexOf to locate a character in a string
String output2 = "'a' is located at index " + text.indexOf ('a') +
text.indexOf('a');
JOptionPane.showMessageDialog( null, output1 + output2,
 "String method indexOf",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
} // end class String IndexOf

// Try this.
String text ="This class is really hard \n" +
"I'm glad I did well on the midterm \n" +
"It took a long time.";
String result="";
for (int i=0; i<text.length(); i++)
{ if (text.charAt(i)=='a')result += "Index: " + i + System.getProperty( "line.separator" ); }
System.out.print(result);

Return from String method

Hi
Can anyone help me:
I have a class with a String method.
The returned value for the method is calculated in a thread. Since I have to share the same literal for the String and run methods, the returned value for the String method is not the value that the run method is supposed to calculate for me. It just wouldn't wait until it's ready.
What should I do? Can I block the String method to return the string until the run method is ready?

Look up Thread.waitFor()

Which String method would be used to...

Which string method (maybe it's not even a string method) would be used to change user input for example from:
User input: Brandon Bell
Changed to Bell, Brandon
Thanks.
Brandon Bell

Which string method (maybe it's not even a string
method) would be used to change user input for
example from:
User input: Brandon Bell
Changed to Bell, Brandon
Your question is very vague. What are the exact requirements? Are you assuming that the inputted string is a first name and a last name, separated by a space, and you want to change it to last name comma first name?
If so, the methods indexOf and substring will be enough for a first, naive implementation. With that in place you might want to ask yourself:
Will you allow the first name to have one or more spaces? Will you allow the last name to have one or more spaces? Etc, etc.

String method compareTo

I am trying to write a program that compares two strings and comes back with the result of wether the first string is "less then", "equal to" or "more then" the second string. I have written the code and will post it. I am only coming across one error, it is saying it cannot resolve the variable "value" in....
displayField.setText("The first string is "+ value +" the secone one!");
here is the code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class CompareWindow extends JFrame{
 private JLabel string1Label,string2Label;
 private JTextField string1Field,string2Field,displayField;
 private JButton exitButton;
public CompareWindow()
super("String method compareTo");
ActionEventHandler handler=new ActionEventHandler();
Container container = getContentPane();
container.setLayout(new FlowLayout() );
string1Label=new JLabel("Enter first string");
string1Field=new JTextField(20);
string1Field.addActionListener(handler);
container.add(string1Label);
container.add(string1Field);
string2Label=new JLabel("Enter second string");
string2Field=new JTextField(20);
string2Field.addActionListener(handler);
container.add(string2Label);
container.add(string2Field);
displayField=new JTextField(30);
displayField.setEditable(false);
container.add(displayField);
exitButton=new JButton("Exit");
exitButton.addActionListener(handler);
container.add(exitButton);
public void displayCompare()
displayField.setText("The first string is "+ value +" the secone one!");
public static void main(String args[])
CompareWindow window = new CompareWindow();
window.setSize(400,140);
window.setVisible(true);
private class ActionEventHandler implements ActionListener{
String first=string1Field.getText();
String second=string2Field.getText();
int compare1=0;
String value;
public void actionPerformed(ActionEvent event)
String first=string1Field.getText();
String second=string2Field.getText();
int compare1=0;
String value;
if (event.getSource()==exitButton)
System.exit(0);
else if (event.getSource()==string1Field) {
compare1=first.compareTo(second);
else if (event.getSource()==string2Field) {
compare1=first.compareTo(second);
if (compare1<0){
value="less then";
else if (compare1==0){
value="equals";
else if (compare1>0){
value="greater then";
displayCompare();
}Any help will be appreciated.

The variable value is not accessible displayCompare method.You will need to pass it as parameter to that displayCompare method or move the declaration to the outer Class i.e. CompareWindow.

Strange about invoking web service method declared string method(void);

Dear forum readers
Im experimenting with OpenESB and web services. Ive create a simple web service using NetBeans 6.1. The method consists of a single method, getTime, that is declared:
String getTime()
My current experiment is to invoke this method from a BPEL-process using the Invoke process object. The strange thing is that it seems like I have to provide a dummy inbound variable from the BPEL-designer even though the method doesnt take any parameters. I include a snippet from the BPEL process below which includes the section where I set the dummy GetTimeIn-variable and then invokes the WS method getTime().
<assign name="Assign2">
<copy>
<from>'DummyValue'</from>
<to variable="GetTimeIn" part="parameters"/>
</copy>
</assign>
<invoke name="Invoke1" partnerLink="PartnerLink1" operation="getTime" xmlns:tns="http://ws/" portType="tns:MyWebService" outputVariable="GetTimeOut" inputVariable="GetTimeIn"/>
If I dont initiate the dummy variable or remove it altogether, I cant successfully call the method. If I include the dummy in-parameter the call works just fine and I get back the current time as a string.
I must admit that Im still a rookie to web services, especially when calling them from a BPEL-process, so it may be a very trivial reason for this behaviour. Anyway, any help on this matter would be greatly appreciated.
Regards, Ola

Thank you both for the response. Regarding Rennays posting I have an additional question. When I create a new web service I don't have the "Document Literal" option nor a "Concrete Configuration" tab. I've created the web service using the "Web Application" project type and then adding a web service using the "Web Service..." wizard. This wizard doesn't have the configuration properties you mention, but if I add a WSDL-file to a BPEL-project the wizard has the properties you mention.
Is it possible to create a web service, programmed as an ordinary Java-class, from an existing WSDL-file? In that case it may solve the problem with the Document Literal property. Currently I dont know any other way to create such a web-service other than the through the web service wizard in a web application project. Of course, its possible to craft it from scratch but thats to much work to be practical.
Regards, Ola

Trouble with a If conditional using string methods.

Hello Everyone,
I am having trouble with an If statement. I want to compare a string variable to two values using the or operator. I have found the || may not be applied to string.equals. Would neone happen to have a different method? Code below:
check = ("C".equals(option)) || ("F".Equals(option));

jverd wrote:
Please paste in the exact, complete error message.
One thing that's definitely wrong is the capital E in your second Equals. I don't know if that's causing the problem though.Also note that, once you get it to compile, if you don't remove the semicolon after the if statement, you won't get the behavior you want.

Problem with a string method

Hello, I am working on a program that converts Roman numerals to Arabic numbers and the opposite. I have the Arabic to Roman part down, yet Roman to Arabic part is causing troubles for me.
I know that there are many solutions out there, yet I would like just solutions within my code that would fix the problem it has.
Instead of the whole code, here's the method that changes Roman to Arabic.
 //method to convert Roman numerals to Arabic numbers
 public static int toArabic (String x)
 int arabica=0;
 char chars;
 for (int y=0; y<=(x.length()-1); y++)
 chars=x.charAt(y);
 switch (chars)
 case 'C':
 if( x.length() == 1)
 arabica+=100;
 y++;
 else if (x.charAt(y+1)=='M')
 arabica+=900;
 y++;
 else if (x.charAt(y+1)=='D')
 arabica+=400;
 y++;
 else
 arabica+=100;
 break;
 case 'X':
 if(x.length() == 1)
 arabica+=10;
 y++;
 else if (x.charAt(y+1)=='C')
 arabica+=90;
 y++;
 else if (x.charAt(y+1)=='L')
 arabica+=40;
 y++;
 else
 arabica+=10;
 break;
 case 'I':
 if(x.length() == 1)
 arabica+=1;
 y++;
 else if (x.charAt(y+1)=='X')
 arabica+=9;
 y++;
 else if (x.charAt(y+1)=='V')
 arabica+=4;
 y++;
 else
 arabica++;
 break;
 case 'M':
 arabica+=1000;
 break;
 case 'D':
 arabica+=500;
 break;
 case 'L':
 arabica+=50;
 break;
 case 'V':
 arabica+=5;
 break;
There's a problem with this, however, is that whenever I put something in like XX, CC, XXX, or II, the program says
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 2
at java.lang.String.charAt(String.java:687)
at RomanNumerals.toArabic(RomanNumerals.java:172)
at RomanNumerals.main(RomanNumerals.java:33)
I think this problem is caused by the if-else and else-if statements in my method for cases C, X, and I, as this problem doesn't come up when I do similar things to cases without the if statements. Could you perhaps find out what is causing this problem? I've been working on it for days after finishing the rest and I can't figure it out.
Thanks

import java.io.*;
public class RomanNumerals{
 public static void main (String [] args)
 DataInput keyboard=new DataInputStream (System.in);
 String input;
 try
 //options
 System.out.println("1. Roman numerals to Arabic numbers");
 System.out.println("2. Arabic numbers to Roman numerals");
 System.out.println("3. Exit");
 System.out.print("Enter your option: ");
 input=keyboard.readLine();
 int choice=Integer.parseInt(input);
 switch (choice)
 //Roman numerals to Arabic numbers
 case 1:
 String romanInput, ro;
 int answer1;
 System.out.print("Enter a Roman numeral: ");
 romanInput=keyboard.readLine();
 ro=romanInput.toUpperCase();
 answer1=toArabic(ro); //line 33 where the error occurs
 System.out.println("The Arabic number is: "+answer1);
 break;
 //Arabic numbers to Roman numerals
 case 2:
 String arabicInput, answer;
 System.out.print("Enter an Arabic number: ");
 arabicInput=keyboard.readLine();
 int arabic=Integer.parseInt(arabicInput);
 answer=toRomans(arabic);
 System.out.println("The Roman numeral is: "+answer);
 break;
 case 3:
 break;
 default:
 System.out.println("Invalid option.");
 catch(IOException e)
 System.out.println("Error");
 //method to convert Arabic numbers to Roman numerals
 public static String toRomans (int N)
 String roman="";
 while (N>=1000)
 roman+="M";
 N-=1000;
 while (N>=900)
 roman+="CM";
 N-=900;
 while (N>=500)
 roman+="D";
 N-=500;
 while (N>=400)
 roman+="CD";
 N-=400;
 while (N>=100)
 roman+="C";
 N-=100;
 while (N>=90)
 roman+="XC";
 N-=90;
 while (N>=50)
 roman+="L";
 N-=50;
 while (N>=40)
 roman+="XL";
 N-=40;
 while (N>=10)
 roman+="X";
 N-=10;
 while (N>=9)
 roman+="IX";
 N-=9;
 while (N>=5)
 roman+="V";
 N-=5;
 while (N>=4)
 roman+="IV";
 N-=4;
 while (N>=1)
 roman+="I";
 N-=1;
 return(roman);
 //method to convert Roman numerals to Arabic numbers
 public static int toArabic (String x)
 int arabica=0;
 char chars;
 for (int y=0; y<=(x.length()-1); y++)
 chars=x.charAt(y);
 switch (chars)
 case 'C':
 if( x.length() == 1)
 arabica+=100;
 y++;
 else if (x.charAt(y+1)=='M')
 arabica+=900;
 y++;
 else if (x.charAt(y+1)=='D')
 arabica+=400;
 y++;
 else
 arabica+=100;
 break;
 case 'X':
 if(x.length() == 1)
 arabica+=10;
 y++;
 else if (x.charAt(y+1)=='C') //the line 172 where error occurs
 arabica+=90;
 y++;
 else if (x.charAt(y+1)=='L')
 arabica+=40;
 y++;
 else
 arabica+=10;
 break;
 case 'I':
 if(x.length() == 1)
 arabica+=1;
 y++;
 else if (x.charAt(y+1)=='X')
 arabica+=9;
 y++;
 else if (x.charAt(y+1)=='V')
 arabica+=4;
 y++;
 else
 arabica++;
 break;
 case 'M':
 arabica+=1000;
 break;
 case 'D':
 arabica+=500;
 break;
 case 'L':
 arabica+=50;
 break;
 case 'V':
 arabica+=5;
 break;
 return(arabica);
 }When I put in XX as the input, this is what the error comes out as:
Enter a Roman numeral: XX
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 2
 at java.lang.String.charAt(String.java:687)
 at RomanNumerals.toArabic(RomanNumerals.java:172)
 at RomanNumerals.main(RomanNumerals.java:33)

Instanceof vs string methods.

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