Java Programming Question

Hi,Everybody:
I have a question about Java programming. If I want to write a java class code called if.java like below, how should I do to make it pass the java compiler and make it work. I know the words "if" and "for" are reserved words. I just try to figure it out that is it possible??? Do I need to create my own java compiler or recompiler?
public class if
public if() { }
public static for test()
return new for();
public class for
public for() { System.out.println("for class constructor"); }
}

I don't think you can bypass the compiler's rejection of this. There is little point to naming the classes after keywords. Not sure if it's case sensitive though, so maybe "If" or "For"? Otherwise, try "if_" or "for_"

Similar Messages

Java Programming Questions

I have taken a couple class in Java programming in just regular programming with GUI/console. I am looking to further my programming skills and wonder what course I need to take to become a java programmer for companies. I am confused on all this language in Java and there does not seem to be any reference to explain exactly what these technologies are. Example is.....What is J2EE? What is .JSP? Are they the same things? What environment is most commonly used in jobs? What about Java certifications?

Here's the path tree to become a Java Programmer from Sun Microsystems:
http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getlppage?page_id=212&path=SJPF
There are other paths like Web Development and Databasing, so click around if you're interested in those. I think for a standard Java Programming job you will want the "Java Programming for Professionals - Sun Certified Java Programmer".
However, most Jobs are specialized and require skills like JSP Development or Java Enterprise. Look around at a job search site and see what types of skills Java jobs are asking for.
I've noticed, for example, that Java web jobs generally require: PHP, HTML, JSP, XML, SQL, etc.

Accessing oracle DB from a java program - question for oracle driver

Hi,
I have Oracle 10 G under vista on my desktop. I am trying to write a simple java program to access/update database tables. I saw in one of oracle example to import 2 packages - namely --- import oracle.jdbc.driver.*; import oracle.sql.*;
Where do I find these 2 packages. Also I read some documentation to download drivers. I would like to use 2 drivers, the thin driver and the OCI driver. Can someone tell me where I can find these drivers and where do I copy these two drivers - so javac and java command can recognize it.
I will greatly appreciate the help. Julia
My program is as follows
(It was working few years ago but things have changed now and I have Vista because my old machine died):
import java.sql.*; // JDBC package
//import com.inet.tds.JDBCRowSet;
import java.util.*;
import oracle.jdbc.driver.*;
import oracle.sql.*;
public class HomeDB
run as follows:
C:\Documents and Settings\MMM>cd \jj
C:\john>set CLASSPATH=.;c:\oracle9i\classes12;%CLASSPATH%
C:\john>javac HomeDB.java
C:\john>java HomeDB
King: 24000.0
Kochhar: 17000.0
De Haan: 17000.0
Hunold: 9000.0
Ernst: 6000.0
Austin: 4800.0
public static void main(String[] argv)throws SQLException
Connection conn=null;
try // may throw a SQLException
conn = getConnection();
doQuery (conn);
catch (SQLException e)
System.err.println(e.getErrorCode() + ": " + e.getMessage());
finally // make sure the connection is closed
if (conn != null) try {conn.close();} catch (SQLException e) {};
//out.close(); // close PrintWriter stream
private static Connection getConnection() throws SQLException
String username = "scott";
String password = "tiger";
String url = "jdbc:oracle:thin:@localhost:1521:newora";
// "jdbc:oracle:thin:@localhost:1521:COCKYJOB";
Connection conn = null;
String driver = "oracle.jdbc.driver.OracleDriver";
try {
Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
} catch ( ClassNotFoundException cnfex ) {
System.err.println(
"Failed to load JDBC/ODBC driver." );
cnfex.printStackTrace();
}catch (Exception e){
e.printStackTrace();
//DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
conn = java.sql.DriverManager.getConnection(url,username,password);
conn.setAutoCommit(false);
return conn;
private static void doQuery (Connection c) throws SQLException
// statement to be executed
String query = "SELECT ename, job, mgr FROM EMP";
Statement st = null;
ResultSet rs = null;
try // make sure the close statements are executed (in the finally block)
// create the statement
st = c.createStatement();
// execute the query
rs = st.executeQuery(query);
// process results
while (rs.next())
// get the employee last name
String eName = rs.getString("ename");
String eJob = rs.getString("job");
String eMgr = rs.getString("mgr");
System.out.println("Emp Name:" + eName +
"Job: " + eJob +
"MGR: " + eMgr);
finally // make sure the close statements are executed
// close the result set if it exists
if (rs != null) try {rs.close();} catch (Exception e) {};
// close the statement if it exists
if (st != null) try {st.close();} catch (Exception e) {};
Edited by: user455788 on Dec 19, 2008 9:13 PM

You can download the drivers from http://www.oracle.com/technology/software/tech/java/sqlj_jdbc/index.html.
Note that oracle.jdbc.driver is desupported after 10.2, http://forums.oracle.com/forums/ann.jspa?annID=201, so you might want to consider using a DataSource to provide Connections.
E.G.
{message:id=2819114}

Java program question

how would i write a java program that takes as input the distance of the commute in miles, the automobiles fuel consumption rate in miles per gallon, and the price of a gallon of gas. this program should then after output the cost of the commute.

how would i write a java program that takes as input
the distance of the commute in miles, the automobiles
fuel consumption rate in miles per gallon, and the
price of a gallon of gas. this program should then
after output the cost of the commute.The same way anyone else would do it.

Table Entry Insert - Java Programming Question

I design table input/output interface with adding / deleting entry function. Table data will be saved in AbstractList by BAPI.
In Controller implementation tab, I created "input" under WD_init()
 Bapi_Entrysheet_Create_Input input = new Bapi_Entrysheet_Create_Input();
 wdContext.nodeBapi_Entrysheet_Create_Input().bind(input);
 input.setEntrysheetheader(new Bapiessrc());
In view action function, I need "input" as.
input.addEntrysheetservices(new Bapiesllc());
My question is how I can let view class know "input".
Thanks.
Message was edited by: li dong
Message was edited by: li dong

Hi li dong,
You need to establish context mapping between view and controller. Open view, select "Properties" tab, In "Required Controllers" section press "Add" and add your controller. Create model node in view (Bapi_Entrysheet_Create_Input) and click "Edit context mapping" in context menu for node. Establish context mapping. Than you can call
wdContext.nodeBapi_Entrysheet_Create_Input().modeObject().addEntrysheetservices(new Bapiesllc());
from view.
Best regards, Maksim Rashchynski.

General java programming question.

i have trouble knowing when something is referred to in contrast to something being copied.
in this case, the array has changed, but not the character.
public class ReturnArray2
 public static int[] getArray()
 int a[] = new int[3];
 a[0] = 2;
 a[1] = 4;
 a[2] = 6;
 return a;
 public static void mystery(int[] b, char r)
 r = 'Q';
 for(int i = 0; i < b.length; i++)
 b[i] = b[i] + 5;
 System.out.println("array b contains: ");
 for(int i = 0; i < 3; i++)
 System.out.println(b[i] + " ");
 public static void main(String args[])
 int scores[];
 char x = 'L';
 scores = getArray();
 System.out.println("Array in main.");
 for (int i = 0; i < 3; i++)
 System.out.println(scores[i] + " ");
 mystery(scores, x);
 System.out.println("After return from mystery.");
 System.out.println("character is " + x);
 for(int i = 0; i < 3; i++)
 System.out.println(scores[i] + " ");
Array in main.
2
4
6
array b contains:
7
9
11
After return from mystery.
character is L
7
9
11
*/and in this case, why didn't the array change?
public class ReturnArray2
 public static int[] getArray()
 int a[] = new int[3];
 a[0] = 2;
 a[1] = 4;
 a[2] = 6;
 System.out.println("array in function");
 for(int i = 0; i < 3; i++)
 System.out.println(a[i] + " ");
 return a;
 public static void mystery(int[] b)
 for(int i = 0; i < b.length; i++)
 b[i] = b[i] * 2 + 5;
 int[] c = new int [3];
 c[0] = 55;
 c[1] = 44;
 c[2] = 33;
 System.out.println("array c contains: ");
 for (int i = 0; i < 3; i++)
 System.out.println(c[i] + " ");
 b = c;
 System.out.println("array b contains: ");
 for(int i = 0; i < 3; i++)
 System.out.println(b[i] + " ");
 public static void main(String args[])
 int scores[];
 scores = getArray();
 System.out.println("Array in main.");
 for (int i = 0; i < 3; i++)
 System.out.println(scores[i] + " ");
 mystery(scores);
 System.out.println("After return from mystery.");
 for(int i = 0; i < 3; i++)
 System.out.println(scores[i] + " ");
array in function
2
4
6
Array in main.
2
4
6
array c contains:
55
44
33
array b contains:
55
44
33
After return from mystery.
9
13
17
*/

i have trouble knowing when something is referred to
in contrast to something being copied.Java has only one passing mode: pass-by-value. The value, whether it be of an int or a reference, is always copied.
in this case, the array has changed, but not the
character.A reference has a value, that value is either null or the address of an Object. The value of scores is the address of the array returned by getArray(). When you pass scores to mystery() the value of scores is copied to a new reference called b on the local stack frame. The value of b is the same as the value of scores, but they are two different references. However, since the value is the same they both contain the same address which is the address of the array. When you modify the array you are modifying the array at the address that b has as it's value. Since scores has that same address as it's value, in other words they both point to the same array, you will see it modified in both places. When you passed the char the value (L) was copied to the local stack frame. Your copy r now has the value L. Modifying r modifies the value at r, which is independent of the value at x.
So, with the char you changed the value at the address. With the reference you changed the value at the address the reference contained as it's value.
and in this case, why didn't the array change?You didn't modify the array, you simply printed it's contents concatenated with an empty String.

Java Programming Language questions...???

Hi everybody....
Can I post here my questions about Java Programming Language....or only to to the relevant Sun's forum....http://forum.java.sun.com/index.jspa???
My greetings,
Simon

Simon,
sure, the worst thing that could happen is that people point you to the SUN forum. Usually this forum answers general Java questions.
Frank

Java programming language main method question?

Hello everyone I am quite new to the Java programming language and I have a question here concerning my main method. As you can see I am calling 4 others methods with my main method. What does the null mean after I call the method? I really don't understand is significance, what else could go there besides null?
public static void main(String[] args)
 int cansPerPack = 6;
 System.out.println(cansPerPack);
 int cansPerCrate = 4* cansPerPack;
 System.out.println(cansPerCrate);
 have_fun(null);
 user_input(null);
 more_java(null);
 string_work(null);
 }Edited by: phantomswordsmen on Jul 25, 2010 4:29 PM

phantomswordsmen wrote:
..As you can see I am calling 4 others methods with my main method. 'Your' main method? Your questions indicate that you did not write the code, who did?
..What does the null mean after I call the method?.. 'null' is being passed as an argument to the method, so there is no 'after the method' about it.
..I really don't understand is significance, what else could go there besides null? That would depend on the method signatures that are not shown in the code snippet posted. This is one of many reasons that I recommend people to post an SSCCE *(<- link).*
BTW - method names like have_fun() do not follow the common nomenclature, and are not good code for a newbie to study. The code should be put to the pointy end of your sword.

Java Programming Competition Sample Questions

Hi,
I am interested in participating the Java Programming Competition in my University. For pratice can you point me to some website with sample questions or any question u have in mind.
Thanks
Satish

I was thinking of putting up on-forum competitions, winner gets dukes etc.
Someone find an empty forum and we can get on it.

Question about Java programming development

There are five phases in java program development. They are: edit -> compile -> load -> verify -> execute
However, every time I develops program. I only experience phase 1, phase 2 and phase 5. I always miss phase 3 and 4. When do the class loader and bytecode verifier work? How do they work?
Second question, how the legitimate programs can execute automatically without typing command java to invoke the interpreter?

lighthero wrote:
I still have some questions.
1. I want to run the program just like the commercial software such as Adobe and MS Office.(just double click to run the program.) How do I execute a java program without typing command java every time?Create an executable JAR: [http://java.sun.com/docs/books/tutorial/deployment/jar/index.html]
>
2. How does the JIT compiler work?[http://www.google.ca/search?q=Java+JIT]

Need help with Java programming installation question

Sorry for my lack of knowledge about Java programming, but:....
A while back I thought I had updated my Java Runtime Environment programming. But I now apparently have two programs installed, perhaps through my not handling the installation properly. Those are:
J2SE Runtime Environment 5.0 update 5.0 (a 118MB file)
and:
Java 2 Runtime Environment, SE v 1.4.2_05 (a 108MB file)
Do I need both of these installed? If not, which should I uninstall?
Or, should I just leave it alone, and not worry about it?
Yeah, I don't have much in the way of technical knowledge...
Any help or advice would be appreciated. Thank you.
Bob VanHorst

Thanks for the feedback. I think I'll do just that. Once in a while I have a problem with Java not bringing up a webcam shot, but when that happens, it seems to be more website based than a general condition.

Running a java program a set number of times

This is a general question. Is it possible to make a java program run only 5 times for the sake of arguement.
Basically I want to write a program that will give the user some flexibility when it will actually run another Java program, but I only want them to be able to say "not now' for a set number of times. When the last time comes the other program will launch. I was initially thinking of the Do Whilw loop, but this needs to work when the program is restarted.
Program starts, it has 5 times it will run before it does something else(doesn't really matter now I think). User takes option "Not Now" and the program ends, but warns the user this will run 4 more times before you will need to do something.
This process will repeat until the user takes the option "Ok install now" or the time limit expires and the install occurs anyway. Can someone point me in the right direction.

ok I see so it's like one those programs that you download for free on the internet and they give you a set amount times to use it before you have to pay for it. but in this case when the number of times you use it equals 5 (or when the user clicks ok) a different java app will open automatically.
My first thought would be to Write a Serialized object to disk using objectOutputStream that stores the number of times the application has been opened. and each time the program runs it checks for the serialized object and then you can do something like what I posted before. of course if were worried about security the user could always look for the object and erase it, if so then I guess we would have to come up with another plan of attack
Hope this helps

Running a Java program at startup in Linux

Hello
How do I run a Java program at startup in Linux? I know in Windows I can put a .bat file in C:\Windows\Start Menu\Programs\StartUp\ directory, but in Linux I have no idea how it is done.
Thank you,
Mihai

This is really a Linux question, not Java.
And then it depends on the version of Linux you are using.
Maybe this will help, otherwise you should try on a forum for your version of Linux.

Running a Java Program for every shut down of system

Hi
I have a java program that sends an email to the Admin of my network.
But this is program i just want to execute for every shutdown and on of my system
Please Tell me how to execute my java program at system shutdown time and on time..
Thanks

Despite your objective, this is not a Java issue. The real question is "How does one run a program just before system shutdown?"
How you execute such an application is system dependent. Java doesn't know when the system shuts down, only when the JVM shuts down. Unless you're willing to have JVM running the entire time the system is up, you'll need native code to detect system shutdown & launch the notification app.

Writing a java program for generating .pdf file with the data of MS-Excel .

Hi all,
My object is write a java program so tht...it'll generate the .pdf file after retriving the data from MS-Excel file.
I used POI HSSF to read the data from MS-Excel and used iText to generate .pdf file:
My Program is:
* Created on Apr 13, 2005
* TODO To change the template for this generated file go to
* Window - Preferences - Java - Code Style - Code Templates
package forums;
import java.io.*;
import java.awt.Color;
import com.lowagie.text.*;
import com.lowagie.text.pdf.*;
import com.lowagie.text.Font.*;
import com.lowagie.text.pdf.MultiColumnText;
import com.lowagie.text.Phrase.*;
import net.sf.hibernate.mapping.Array;
import org.apache.poi.hssf.*;
import org.apache.poi.poifs.filesystem.*;
import org.apache.poi.hssf.usermodel.*;
import com.lowagie.text.Phrase.*;
import java.util.Iterator;
* Generates a simple 'Hello World' PDF file.
* @author blowagie
public class pdfgenerator {
     * Generates a PDF file with the text 'Hello World'
     * @param args no arguments needed here
     public static void main(String[] args) {
          System.out.println("Hello World");
          Rectangle pageSize = new Rectangle(916, 1592);
                    pageSize.setBackgroundColor(new java.awt.Color(0xFF, 0xFF, 0xDE));
          // step 1: creation of a document-object
          //Document document = new Document(pageSize);
          Document document = new Document(pageSize, 132, 164, 108, 108);
          try {
               // step 2:
               // we create a writer that listens to the document
               // and directs a PDF-stream to a file
               PdfWriter writer =PdfWriter.getInstance(document,new FileOutputStream("c:\\weeklystatus.pdf"));
               writer.setEncryption(PdfWriter.STRENGTH128BITS, "Hello", "World", PdfWriter.AllowCopy | PdfWriter.AllowPrinting);
//               step 3: we open the document
                         document.open();
               Paragraph paragraph = new Paragraph("",new Font(Font.TIMES_ROMAN, 13, Font.BOLDITALIC, new Color(0, 0, 255)));
               POIFSFileSystem pofilesystem=new POIFSFileSystem(new FileInputStream("D:\\ESM\\plans\\weekly report(31-01..04-02).xls"));
               HSSFWorkbook hbook=new HSSFWorkbook(pofilesystem);
               HSSFSheet hsheet=hbook.getSheetAt(0);//.createSheet();
               Iterator rows = hsheet.rowIterator();
                              while( rows.hasNext() ) {
                                   Phrase phrase=new Phrase();
                                   HSSFRow row = (HSSFRow) rows.next();
                                   //System.out.println( "Row #" + row.getRowNum());
                                   // Iterate over each cell in the row and print out the cell's content
                                   Iterator cells = row.cellIterator();
                                   while( cells.hasNext() ) {
                                        HSSFCell cell = (HSSFCell) cells.next();
                                        //System.out.println( "Cell #" + cell.getCellNum() );
                                        switch ( cell.getCellType() ) {
                                             case HSSFCell.CELL_TYPE_STRING:
                                             String stringcell=cell.getStringCellValue ()+" ";
                                             writer.setSpaceCharRatio(PdfWriter.NO_SPACE_CHAR_RATIO);
                                             phrase.add(stringcell);
                                        // document.add(new Phrase(string));
                                                  System.out.print( cell.getStringCellValue () );
                                                  break;
                                             case HSSFCell.CELL_TYPE_FORMULA:
                                                       String stringdate=cell.getCellFormula()+" ";
                                                       writer.setSpaceCharRatio(PdfWriter.NO_SPACE_CHAR_RATIO);
                                                       phrase.add(stringdate);
                                             System.out.print( cell.getCellFormula() );
                                                       break;
                                             case HSSFCell.CELL_TYPE_NUMERIC:
                                             String string=String.valueOf(cell.getNumericCellValue())+" ";
                                                  writer.setSpaceCharRatio(PdfWriter.NO_SPACE_CHAR_RATIO);
                                                  phrase.add(string);
                                                  System.out.print( cell.getNumericCellValue() );
                                                  break;
                                             default:
                                                  //System.out.println( "unsuported sell type" );
                                                  break;
                                   document.add(new Paragraph(phrase));
                                   document.add(new Paragraph("\n \n \n"));
               // step 4: we add a paragraph to the document
          } catch (DocumentException de) {
               System.err.println(de.getMessage());
          } catch (IOException ioe) {
               System.err.println(ioe.getMessage());
          // step 5: we close the document
          document.close();
My Input from MS-Excel file is:
     Planning and Tracking Template for Interns
     Name of the Intern     N.Kesavulu Reddy
     Project Name     Enterprise Sales and Marketing
     Description     Estimated Effort in Hrs     Planned/Replanned          Actual          Actual Effort in Hrs     Complexity     Priority     LOC written new & modified     % work completion     Status     Rework     Remarks
S.No               Start Date     End Date     Start Date     End Date
1     setup the configuration          31/01/2005     1/2/2005     31/01/2005     1/2/2005
2     Deploying an application through Tapestry, Spring, Hibernate          2/2/2005     2/2/2005     2/2/2005     2/2/2005
3     Gone through Componentization and Cxprice application          3/2/2005     3/2/2005     3/2/2005     3/2/2005
4     Attend the sessions(tapestry,spring, hibernate), QBA          4/2/2005     4/2/2005     4/2/2005     4/2/2005
     The o/p I'm gettint in .pdf file is:
Planning and Tracking Template for Interns
N.Kesavulu Reddy Name of the Intern
Enterprise Sales and Marketing Project Name
Remarks Rework Status % work completion LOC written new & modified Priority
Complexity Actual Effort in Hrs Actual Planned/Replanned Estimated Effort in Hrs Description
End Date Start Date End Date Start Date S.No
38354.0 31/01/2005 38354.0 31/01/2005 setup the configuration 1.0
38385.0 38385.0 38385.0 38385.0 Deploying an application through Tapestry, Spring, Hibernate
2.0
38413.0 38413.0 38413.0 38413.0 Gone through Componentization and Cxprice application
3.0
38444.0 38444.0 38444.0 38444.0 Attend the sessions(tapestry,spring, hibernate), QBA 4.0
                                   The issues i'm facing are:
When it is reading a row from MS-Excel it is writing to the .pdf file from last cell to first cell.( 2 cell in 1 place, 1 cell in 2 place like if the row has two cells with data as : Name of the Intern: Kesavulu Reddy then it is writing to the .pdf file as Kesavulu Reddy Name of Intern)
and the second issue is:
It is not recognizing the date format..it is recognizing the date in first row only......
Plz Tell me wht is the solution for this...
Regards
[email protected]

Don't double post your question:
http://forum.java.sun.com/thread.jspa?threadID=617605&messageID=3450899#3450899
/Kaj

Java Programming Question

Similar Messages

Maybe you are looking for