New to java plz hep me
hello all,
i'm new to java. i need to know answers to these questions..
1. What is the purpose of CLASSPATH? How �classpath� is used by �java� and �javac�?
2. What is the purpose of finally block?
3. What is �Ant�?
4. Explain the difference between abstract class and interface. When to use an abstract class and when to use an interface?
5. What is the purpose of �Xms option of �java�?
6. What is the main difference between java.util.Date class and java.util.Calendar class?
7. What are the differences between wait and sleep methods?
8. What is the advantage of using ArrayList over Vector?
9. Explain the word �casting�
could u plz help me.. i need them very much..
1. What is the purpose of CLASSPATH? How �classpath�
is used by �java� and �javac�?Classpath is the paths along which javac or the jvm searches for classes to load.
2. What is the purpose of finally block?Cleanup if something went wrong
>
3. What is �Ant�? Ant is a preprocessor, kinda like .bat files.
>
4. Explain the difference between abstract class and
interface. When to use an abstract class and when to
use an interface?You should really google this. It's hard to answer this in 1 line
>
5. What is the purpose of �Xms option of �java�?Increase the java heap size
6. What is the main difference between java.util.Date
class and java.util.Calendar class?RTFM http://java.sun.com/j2se/1.5.0/docs/api/
>
7. What are the differences between wait and sleep
methods?sleep sleeps. Wait and Notify work together in multithreaded apps.
>
8. What is the advantage of using ArrayList over
Vector?It is faster
>
9. Explain the word �casting�In the harry potter sense of the word?
Object o = "hi";
String s = (String) o;
Similar Messages
-
Well I'm not that new. I've been working with java for two years using jcreator in school. Its been great, we make lots of programs and run em and stuff. But the one thing we didn't learn is how to distribute the programs to other people. For instance, if I make a program to help with math homework......and I wanna give that to my friend........i'd hafta send em the source files and they'd hafta open it up in jcreator and run it........that seems kinda not good........how do u make it into an actual thing that I can click on and it runs like any normal program (exe?)
yea, heres a lot of code that calculates the Flesch readability of a piece of writing.
import java.io.*;
public class Flesch
private int mySentences, myWords, mySyllables, temp, flag, tempSyl;
private char check,hold,back;
private String myFile,myLevel;
private double myScore;
public Flesch()
mySentences=0;
myWords=0;
tempSyl=0;
mySyllables=0;
myLevel="";
myScore=0.0;
temp=0;
flag=0;
public Flesch(String file) throws IOException
myFile=file+".txt";
public String getFilename()
return myFile;
public double getLegibilityIndex()
myScore=Math.round(206.835 - (84.6*(((double)(mySyllables+1)/(double)myWords))) - (1.015*((double)myWords/(double)mySentences)));
return myScore;
public String getEducationalLevel()
if(myScore>=91)
myLevel="5th Grade";
else if(myScore>=81)
myLevel="6th Grade";
else if(myScore>=71)
myLevel="7th Grade";
else if(myScore>=61)
myLevel="8th and 9th Grade";
else if(myScore>=51)
myLevel="10th to 12th Grade";
else if(myScore>=31)
myLevel="College Student";
else myLevel="College Graduate";
return myLevel;
public int getNumSentences()throws IOException
FileReader sent=new FileReader(myFile);
temp=sent.read();
while(temp!=-1)
check=(char)temp;
if(check=='?'||check=='!'||check=='.')
mySentences++;
temp=sent.read();
sent.close();
return mySentences;
public int getNumWords()throws IOException
FileReader word=new FileReader(myFile);
hold='@';
temp=word.read();
while(temp!=-1)
check=(char)temp;
if((check==' '||check=='\n'))
myWords++;
hold=check;
temp=word.read();
if(temp==-1)
myWords++;
word.close();
return myWords;
public boolean isVowel(char c)
if(c=='a'||c=='e'||c=='i'||c=='o'||c=='u'||c=='y'||c=='A'||c=='E'||c=='I'||c=='O'||c=='U'||c=='Y')
return true;
return false;
public boolean isPunc(char c)
if(c=='.'||c=='!'||c=='?'||c==','||c==':'||c=='-'||c==';')
return true;
return false;
public int getNumSyllables() throws IOException
FileReader syl=new FileReader(myFile);
tempSyl=mySyllables;
hold='@';
back='@';
temp=syl.read();
while(temp!=-1)
check=(char)temp;
System.out.print(check);
if(isVowel(check)&&!isVowel(hold))
mySyllables++;
if(hold=='e'&&(check==' '||isPunc(check)||check=='\n'||check=='\r'||check=='\f'))
mySyllables--;
if(tempSyl==mySyllables&&(check==' '||check=='\n')&&hold!=' ')
mySyllables++;
if(check==' '||check=='\n')
tempSyl=mySyllables;
if(flag>=1)
back=hold;
hold=check;
temp=syl.read();
flag++;
syl.close();
System.out.println("");
return mySyllables; -
Hi
i am 100% new to java, plz help, i have good concepts of programing but i dont know any thing about java. so plz tell me how to start, what should i install n from where to download,
i will be so thank full to u
plz email me at [email protected]
regards
imranHi! I am also new to java. I was suggested in this forum two days back to start at Java Tutorial, and I am really thankful to the person who suggested me the tutorial. Its a good starting point.
http://java.sun.com/docs/books/tutorial/
Hope you find it useful too. -
Hey im brand new to java and i just downloaded and installed jdk-1_5_0_01-windows-i586-p now im tryin to set up the PATH permanently but i have no clue how to i went to the install notes and typed in C:\Program Files\Java\jdk1.5.0_<windows>\bin in the command.com but everytime i do it says access is denied. i have no clue how to set up the path permanently beside what i tried plz help!!!
You didn't which OS you are running, but it's fairly similar for all windows.
Start->settings->control panel->system->advanced->environment variables
Go to System variables, click on path, click edit button and add a semicolon and the path at the end. DO NOT REPLACE EVERYTHING THAT'S THERE NOW.
I don't have 1.5 installed on this computer, but I'm willing to bet the real path doesn't have '<windows>' in it. Use Windows Explorer to find out where java.exe actually exists on the hard disk and use that path -
I've created simple data base in sql and a simple html page,here is the code:
<%@ page import="java.util.*" import="java.sql.*" %>
<%!
private String emp_code, emp_name, emp_dept, emp_title, emp_doj, emp_dob;
private String error, info, create;
private short age;
private Statement stmt;
%>
<%
//load the JDBC driver
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection conn = DriverManager.getConnection("jdbc:odbc:Master","","");
Statement s = conn.createStatement();
s.executeUpdate("insert into employee_info values('" + emp_code + "', '" + emp_name + "','" + emp_dept + "','" + emp_title + "', '" + emp_doj + "','" + emp_dob + "') ");
System.out.println ("It has been successfully added");
%>
<HTML>
<HEAD>
<TITLE> ---: New Employee Information :--- </TITLE>
</HEAD>
<BODY>
<DIV ALIGN="center">
<H2> New Employee Information </H2></DIV>
<DIV ALIGN="center">
<p> � </p></DIV>
<FORM METHOD = "POST" ACTION = "NewEmp.jsp">
<H4>Employee Code: <INPUT TYPE= "text" NAME = "first1" SIZE = "17">����
Name: <INPUT TYPE = "TEXT" NAME = "first" SIZE = "51">�������
<font size="3">Title:�<SELECT name="Grade">
<OPTION SELECTED> - Select -
<OPTION >Programmer
<OPTION >Technetion
<OPTION>System Analyst
<OPTION>Network Administrator
</SELECT>�</font>
</H4>
<H4><font size="3">�</font>
</H4>
<H4><font size="3">Department Code:�</font><select name="Dept">
<OPTION SELECTED> - Select -
<OPTION >IT
<OPTION >Admin
<OPTION>MGM
<OPTION>CSD
<OPTION>SM
<OPTION>FIN
</SELECT>
��������
<font size="3"><b>DOB: </b> </font> <INPUT TYPE = "TEXT" NAME = "first2" SIZE = "18">������
<b><font size="3">DOJ: </font></b><INPUT TYPE = "TEXT" NAME = "first3" SIZE = "18">
</H4>
<p>�
</p>
<P align="center">
<INPUT TYPE = "SUBMIT" VALUE = "Submit">
<INPUT TYPE = "RESET">
<input type="button" value="Cancel" name="Cancel" onClick='javascript:window.close();'> </FORM>
<p align="center">�</p>
</BODY>
</HTML>
But I couldn't complete it or make the connection to the database, I want to fill in the blanks and then add it to the data base.
My database name is doctrak and the table name is employee_info and below the design of the table :
emp_code char 10
emp_name char 30
emp_dept char 15
emp_title char 10
emp_doj datetime 8
emp_dob datetime 8
I've installed the apatchi tomcat 401 and make the java environment.
So plz can any one help me in that?
ThanksBut I don't know how to handel the code, I didn't
study JSP or Java. I'm trying to learn it by doing
this, so please can you write the code for me in jsp
and how to put it in html then , how to do the
connection to my database?Iam sorry to disappoint you, but no.
If you are new to java and jsp taking up such a task to learn it is not ideal, nor
viable. I would suggest you learn the basics of the language first, then the basics
of jsp, then some jdbc and finally graduate to the example in question. There are
excellent tutorials avbl for all on the net.
Maybe someone else would even post the code here, but suggest you dont
waste time waiting on it.
All the best.
Cheers,
ram. -
Convert C++ prog into Java( I m new in java)help urgent
hi all,
i am very new in java. i have code of C++.i have to convert it in to Java.please help me on urgent basis.plz provide me solution.
I am looking for positive response.code is below:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fstream.h>
#include <iostream.h>
//#include <sha.h> //24112003
//#include<wincrypt.h>
char ntc(unsigned char n){
if (n<26) return 'A'+n;
if (n<52) return 'a'-26+n;
if (n<62) return '0'-52+n;
if (n==62) return '+';
if (n==63)return '/';
unsigned char ctn(char c){
if (c=='/') return 63;
if (c=='+') return 62;
if ((c>='A')&&(c<='Z')) return c-'A';
if ((c>='a')&&(c<='z')) return c-'a'+26;
if ((c>='0')&&(c<='9')) return c-'0'+52;
if (c=='~') return 80;
return 100;
int b64decode(char from,char to,int length){
unsigned char c,d,e,f;
char A,B,C;
int i;
int add;
char *tot=to;
for (i=0;i+3<length;){
add=0;
A=B=C=0;
c=d=e=f=100;
while ((c==100)&&(i<length)) c=ctn(from[i++]);
while ((d==100)&&(i<length)) d=ctn(from[i++]);
while ((e==100)&&(i<length)) e=ctn(from[i++]);
while ((f==100)&&(i<length)) f=ctn(from[i++]);
//if (f==100) return -1; /* Not valid end */
if (c<64) {
A+=c*4;
if (d<64) {
A+=d/16;
B+=d*16;
if (e<64) {
B+=e/4;
C+=e*64;
if (f<64) {
C+=f;
to[2]=C;
add+=1;
to[1]=B;
add+=1;
to[0]=A;
add+=1;
to+=add;
if (f==80) return to-tot; /* end because '=' encountered */
return to-tot;
int b64get_encode_buffer_size(int l,int q){
int ret;
ret = (l/3)*4;
if (l%3!=0) ret +=4;
if (q!=0){
ret += (ret/(q*4));
/* if (ret%(q/4)!=0) ret ++; */ /* Add space for trailing \n */
return ret;
int b64strip_encoded_buffer(char *buf,int length){
int i;
int ret=0;
for (i=0;i<length;i++) if (ctn(buf)!=100) buf[ret++] = buf [i];
return ret;
int b64encode(char from,char to,int length,int quads){
// 3 8bit numbers become four characters
int i =0;
char *tot=to;
int qc=0; // Quadcount
unsigned char c;
unsigned char d;
while(i<length){
c=from[i];
*to++=ntc(c/4);
c=c*64;
i++;
if (i>=length) {
*to++=ntc(c/4);
*to++='~';
*to++='~';
break;
d=from[i];
*to++=ntc(c/4+d/16);
d=d*16;
i++;
if (i>=length) {
*to++=ntc(d/4);
*to++='~';
break;
c=from[i];
*to++=ntc(d/4+c/64);
c=c*4;
i++;
*to++=ntc(c/4);
qc++; /* qz will never be zero, quads = 0 means no linebreaks */
if (qc==quads){
*to++='\n';
qc=0;
/* if ((quads!=0)&&(qc!=0)) to++='\n'; / /* Insert last linebreak */
return to-tot;
char* mEncryptPassword(char* mPassword)
char mEncryptedPassword[200]; // To hold encrypted password.
//char* mEncryptedPassword = new char[200];
char mPrimEncryptedPassword[200];
char * temp = new char[200];
//unsigned char* md; // 19122003
//md = new unsigned char[100]; // 19122003
memset(mEncryptedPassword, '\0', sizeof(mEncryptedPassword));
memset(mPrimEncryptedPassword, '\0', sizeof(mPrimEncryptedPassword));
strcpy(mPrimEncryptedPassword, mPassword);
//strcpy(mPrimEncryptedPassword, (char*) SHA1((unsigned char*) mPassword, strlen(mPassword), NULL));
//strcpy(mEncryptedPassword, (char*) SHA((unsigned char*) mPassword, strlen(mPassword), md)); // 19122003
//strcpy(mEncryptedPassword, (char*) SHA((unsigned char*) mPassword, strlen(mPassword), md)); //19122003
b64encode(mPrimEncryptedPassword, mEncryptedPassword, strlen(mPrimEncryptedPassword), 0);
// If successfully encrypts..
if (mEncryptedPassword != NULL)
//char * temp = new char[strlen(mEncryptedPassword)+1];
strcpy(temp,mEncryptedPassword);
// strcpy(mRetVal,mEncryptedPassword);
return (char*)temp;
//return (mEncryptedPassword);
//return (char*) md; // 19122003
else
return ("Error");
char* mDecryptPassword(char* mPassword)
char mDecryptedPassword[200]; // To hold decrypted password.
char mPrimDecryptedPassword[200];
char * temp = new char[200];
// 02032007
memset(mDecryptedPassword, '\0', sizeof(mDecryptedPassword));
memset(mPrimDecryptedPassword, '\0', 200);
strcpy(mPrimDecryptedPassword, mPassword);
b64decode(mPrimDecryptedPassword, mDecryptedPassword, strlen(mPrimDecryptedPassword));
// If successfully decrypts..
if (mDecryptedPassword != NULL)
//char * temp = new char[strlen(mEncryptedPassword)+1];
strcpy(temp,mDecryptedPassword);
// strcpy(mRetVal,mDecryptedPassword);
return (char*)temp;
//return (mEncryptedPassword);
//return (char*) md; // 19122003
else
return ("Error");
void main(int argc, char* argv[])
cout << mEncryptPassword(argv[1])<<endl<<flush;
cout << mDecryptPassword(mEncryptPassword(argv[1]))<<endl<<flush;
Anubhavendasil wrote:
I just thought of how ridiculous this would sound in any other profession:
Surgeons:
plz plz help I have patient dying need to insert new kidney into 90yr old patient plz someone come do itLawyers:
Help client guilty need good defense (I m new in law)help urgentHow come we get stuck with the lazy low-lifes?Because there's no legal requirement that a software developer must be licensed -
How can I open help file (HTML or .chm) from Java Web Start (new to JAVA)
Hi All,
Im trying to open the help file of my application.
When trying to access the help file from the GUI (pressing F1 for launching the help file), I'm geting the an error, something like:
"Can't show help URL: jar:file:C:\Documents and Settings\%USER%\Application Data\Sun\Java\Deployment\javaws\cache\http\Dlocalhost\P7001\DMwebstart\RMjar-name!/com/resources/helpFiles/MyHelpFile.html"
It seems that the file which is packed in a jar, was downloaded to the Java Web Start cache directory:
C:\Documents and Settings\%USER%\Application Data\Sun\Java\Deployment\javaws\cache\http\Dlocalhost\P7001\DMwebstart
The code which is activated when launching the help file is:
try
ResourceBundle resourceBundle = DoubleResourceBundle.getBundle("Resource", "ResourceImpl");
RuntimeUtil.launchFile(new File(resourceBundle.getString("help.file")));
} catch (IOException e)
// TODO Auto-generated catch block
e.printStackTrace();
}where the property "help.file" is in some property file in the resource bundle named "Resource", and looks like this :
help.file="com/trax/docs/help/global/MyHelpFile.html"
The function "RuntimeUtil.launchFile" knows how to launch any file in its default application, and indeed it does launches the html, when giving it an absolute path to the file on my PC, as "C:\Helpfiles\MyHelpFile.html" as such:
RuntimeUtil.launchFile("C:\Helpfiles\MyHelpFile.html");My question is :
The application is going to be deployed on a Customer PC. How can I access the html file from the code, with a relative path and not its absolute path on the customer pc, which I can't know?
I found these restrictions regarding web start:
(copied from "http://rachel.sourceforge.net/"):
*Rule 1: Java Archives only. No loose files.* All your resources have to be packaged in Java Archives (jar) if you want to have
them delivered to the user's machine and kept up-to-date automatically by Java Web Start.
*Rule 2: No file paths.* You can't use absolute or relative file paths to locate your
jars holding your resources (e.g. <code>jar:file:///c:/java/jws/.cache/resources.jar</code>).
Absolute file paths won't work because you never know where Java Web Start
will put your jar on the user's machine. Relative file paths won't work because Java Web Start
mangles the names of your jars (e.g. <code>venus.jar</code> becomes <code>RMvenus.jar</code>)
and every JNLP client implementation has the right to mangle your names
in a different way and you, therefore, can't predict the name with
which your jar will be rechristend and end up on the user's machine in
the application cache.Seems complex or impossible, to perform a simple task like opening a file.
Please advise (I'm new to Java and Web Start).
BTW, I'm working with IntelliJ IDEA 5.0.
Thanks,
Zedik.
{font:Tahoma}{size:26pt}
{size}{font}the follwing method i have used to open html file ...
so to access html file i am shipping resources folder with jar file ..
private void openHtmlPages(String pageName) {
String cmd[] = new String[2];
String browser = null;
File file = null;
if(System.getProperty("os.name").indexOf("Linux")>-1) {
file = new File("/usr/bin/mozilla");
if(!file.exists() ) {
}else {
browser = "mozilla";
}else {
browser = "<path of iexplore>";
cmd[0] = browser;
File files = new File("");
String metaData = "/resources/Help/Files/"+pageName+".html"; // folder inside jar file
java.net.URL url = this.getClass().getResource(metaData);
String fileName = url.getFile();
fileName = fileName.replaceAll("file:/","");
fileName = fileName.replaceAll("%2520"," ");
fileName = fileName.replaceAll("%20"," ");
fileName = fileName.replaceAll("jarfilename.jar!"," ").trim();
cmd[1] = fileName;
try{
Process p = Runtime.getRuntime().exec(cmd);
}catch(java.io.IOException io){
//Ignore
can anyone give me the solution..???
Regards
Ganesan S -
i just bought 200 GB storage for my phone and it still says i cant download apps because "there's no enough storage" i don't get why, plz hep me out!!!
It means that you need to delete content from the device before you can add more.
(115750) -
What is new in Java syntaxes in new Java versions?
What is new in Java syntaxes in new Java versions?
What about this sentenses
1. for (int c:data), where data is array of integer
2. ArrayList<Object> () ...
3. Class<?>...
I can't find this syntaxes in my books and documentation...
And what Java version is latest?dont crosspost
Edited by language police -
Anybody can quickly explain the things are added in Java 4 newly.
Thnx in advance.Nothing's new in Java 4 because there is no Java 4.
Maybe you mean Java 5?
Or maybe you mean Java 1.4?
In either case, either the download page for that version, or the installation, should have release notes that answer your question.
In fact, here they are for Java 5:
http://java.sun.com/j2se/1.5.0/docs/relnotes/features.html -
Dear Forummembers,
I am student doing postgraduate studies in IT.i have some queries related to one of my programming staff.i am very much new into Java programming and i am finding it a bit difficult to handle this program.The synopsis of the program is given below -
You are required to design and code an object-oriented java program to process bookings for a theatre perfomance.
Your program will read from a data file containing specifications of the performance,including the names of the theatre, the play and its author and the layout of the theatre consisting of the number of seats in each row.
It will then run a menu driven operation to accept theatre bookings or display the current
status of seating in the theatre.
The name of the file containing the details of the performance and the theatre should be
provided at the command line, eg by running the program with the command:
java Booking Theatre.txt
where Theare.txt represents an example of the data file.
A possible data file is:
Opera
U and Me
Jennifer Aniston
5 10 10 11 12 13 14
The data provided is as follows
Line 1
Name of the Theatre
Line 2
Name of the play being performed
Line 3
Name of the author of the play being performed
Line 4
A list of the lengths (number of seats) of each row in the theatre, from front to
back.
The program must start by reading this file, storing all the appropriate parameters and
establishing an object to accept bookings for this performance with all details for the theatre
and performance.
The program should then start a loop in which a menu is presented to the user, eg:
Select from the following:
B - Book seats
T - Display Theatre bookings
Q - Quit from the program
Enter your choice:
And keep performing selected operations until the user�s selects the quit option, when the
program should terminate.
T - Display Theatre bookings
The Display Theatre Bookings option should display a plan of the theatre. Every available
seat should be displayed containing its identification, while reserved seats should contain an
Rows in each theatre are indicated by letters starting from �A� at the front. Seats are
numbered from left to right starting from 1. A typical seat in the theatre might be designated
D12, representing seat 12 in row D.
B - Book seats
The booking of seats is to offer a number of different options.
First the customer must be asked how many adjacent seats are
required. Then start a loop offering a further menu of choices:
Enter one of the following:
The first seat of a selected series, eg D12
A preferred row letter, eg F
A ? to have the first available sequence selected for you
A # to see a display of all available seats
A 0 to cancel your attempt to book seats
Enter your selection:
1. If the user enters a seat indentifier such B6, The program should attempt to
reserve the required seats starting from that seat. For example if 4 seats are
required from B6, seats B6, B7, B8 and B9 should be reserved for the customer,
with a message confirming the reservation and specifying the seats reserved..
Before this booking can take place, some testing is required. Firstly, the row
letter must be a valid row. Then the seat number must be within the seats in the
row and such that the 4 seats would not go beyond the end of the row. The
program must then check that none of the required seats is already reserved.
If the seats are invalid or already reserved, no reservation should be made and the
booking menu should be repeated to give the customer a further chance to book
seats.
If the reservation is successful, return to the main menu.
2. The user can also simply enter a row letter, eg B.IN this case, the program should
first check that the letter is a valid row and then offer the user in turn each
adjacent block of the required size in the specified row and for each ask whether
the customer wants to take them. Using the partly booked theatre layout above, if
the customer wanted 2 seats from row B, the customer should be offered first:
Seats B5 to B6
then if the customer does not want them:
Seats B10 to B11
and finally
Seats B11 to B12
If the customer selects a block of seats, then return to the main menu. If none are
selected, or there is no block of the required size available in the row, then report
that no further blocks of the required size are available in the row and repeat the
booking menu.
3. If the user enters a ? the program should offer the customer every block of seats
of the required size in the whole theatre. This process should start from the first
row and proceed back a row at a time. For example, again using the partially
booked theatre shown above, if the user requested 9 seats, the program should
offer in turn:
Seats A1 to A9
Seats C1 to C9
Seats C2 to C10
Seats E3 to E11
Seats E4 to E12
If the customer selects a block of seats, then return to the main menu. If none are
selected, or there is no block of the required size available in the whole theatre,
then report that no further blocks of the required size are available and repeat the
booking menu.
4. If the user enters a # the program should display the current status of the seating
in the theatre, exactly the same as for the T option from the main menu and then
repeat the booking menu.
5. If the user enters a 0 (zero), the program should exit from the booking menu back
to the main menu. If for example the user wanted 9 seats and no block of 9 was
left in the theatre, he would need to make two separate smaller bookings.
The program should perform limited data validation in the booking process. If a single
character other than 0, ? and # is entered, it should be treated as a row letter and then tested
for falling within the range of valid rows, eg A to H in the example above. Any invalid row
letters should be rejected.
If more than one character is entered, the first character should be tested as a valid row letter,
and the numeric part should be tested for falling within the given row. You are NOT
required to test for valid numeric input as this would require the use of Exception handling.
You are provided with a class file:
Pad.java
containing methods that can be used for neat alignment of the seat identifiers in the theatre
plan.
File Processing
The file to be read must be opened within the program and if the named file does not exist, a
FileNotFoundException will be generated. It is desirable that this Exception be caught and
a corrected file name should be asked for.
This is not required for this assignment, as Exception handling has not been covered in this
Unit. It will be acceptable if the method simply throws IOException in its heading.
The only checking that is required is to make sure that the user does supply a file on the
command line, containing details of the performance. This can be tested for by checking the
length of the parameter array args. The array length should be 1. If not, display an error
message telling the user the correct way to run the program and then terminate the program
System.exit(0);
The file should be closed after reading is completed.
Program Requirements
You are expected to create at least three classes in developing a solution to this problem.
There should be an outer driving class, a class to represent the theatre performance and its
bookings and a class to represent a single row within the theatre.
You will also need to use arrays at two levels. You will need an array of Rows in the Theatre
class.
Each Row object will need an array of seats to keep track of which seats have been reserved.
Your outer driving class should be called BookingOffice and should be submitted in a file named BookingOffice.java
Your second, third and any additional classes, should be submitted in separate files, each
class in a .java file named with the same name as the class
I am also very sorry to give such a long description.but i mainly want to know how to approach for this program.
also how to designate each row about it's column while it is being read from the text file, how to store it, how to denote first row as row A(second row as row B and so on) and WHICH CLASS WILL PERFORM WHICH OPERATIONS.
pls do give a rough guideline about designing each class and it's reponsibilty.
thanking u and looking forward for your help,
sincerely
RKyes i do know that........but can u ppl pls mention
atleast what classes shud i consider and what will be
the functions of each class?No, sorry. Maybe somebody else will, but in general, this is not a good question for this forum. It's too broad, and the question you're asking is an overall problem solving approach that you should be familiar with at this point.
These forums are best suited to more specific questions. "How do I approach this homework?" is not something that most people are willing or able to answer in a forum like this. -
New to JAVA, but old school to programming
Objects & Classes & Methods, Oh my!
I'm pretty new to java, but I've been programming in several languages over the years. I thought it was about time to update my skill set, especially with the job market as it is today. I wanted to go JAVA because it's not specific to any environment.
I picked up a begining JAVA book and was a little confused. When I was learning programming a program was called a program. a peice of code in a program called by a statement was called a subroutine (it was performed then control returned to the calling line and continued).
Now I'm trying to make sense of everything I have read so far and trying to relate it back to my old school of thinking. I was hoping it would make it easier to retain and I could expand it as I learn and possibly realize that it IS different. I know it's a new way of thinking, but stay with me for minute.
What I used to call a program is now a CLASS in JAVA (this can be a collection of code or other objects). A sub-routine in a CLASS is a Method. I know that the language part will come as I use it since I understand if's then's and whatever you use to gosub or goto, but I want to make sure I have down the lingo before I go to deep.I have no idea how you can compare Java to Cobol.
DataFlex? How about that! In about '84 I switched to
DataFlex from dBaseII. In '91 DataFlex changed from
procedural to OOP. It took most of us at least a year
to adjust, and then some to write concrete code. It
was tough. They had bugs and we were limited with DOS.
BUT, it was a great OOP training experience. Anyhow,
needless to day Java is miles ahead on all fronts.Small world. I was stuck in the old DataFlex Ver 2.3 at that time. The company I worked for had the newer OOP package. I did get to work with it some, but not enough to become totally familiar with it. We started to move out of DataFlex towards PowerBuilder towards the end of 1995. I did get some OOP from that experience, but again only enough to learn about global variables, instance variables, and a few other items. I hoping that I will be able to get the solid OOP background that I need from JAVA since I hear through the grapevine that it may be a new tool that we will be looking at to enhance our programming. I was looking at PERL but even the PERL programmers we have agree that JAVA is more scalable. -
New to Java and need help with this program..please!
I'd really appreciate any helpful comments about this program assignment that I have to turn in a week from Friday. I'm taking a class one night a week and completely new to Java. I'd ask my professor for help, but we can't call him during the week and he never answers e-mails. He didn't tell us how to call from other classes yet, and I just can't get the darn thing to do what I want it to do!
The assignment requirements are:
1. Change a card game application that draws two cards
and the higher card wins, to a Blackjack application
2. Include a new class called Hand
3. The Hand class should record the number of draws
4. The application should prompt for a number of draws
5. The game is played against the Dealer
6. The dealer always draws a card if the dealer's hand total is <= 17
7. Prompt the player after each hand if he wants to quit
8. Display the total games won by the dealer and total and the total games wond by the player after each hand
9. Display all of the dealer's and player's cards at the
end of each hand
10. Player has the option of drawing an additional card after the first two cards
11. The Ace can have a value of 11 or 1
(Even though it's not called for in the requirements, I would like to be able to let the Ace have a value of 1 or an 11)
The following is my code with some comments about a few things that are driving me nuts:
import java.util.*;
import javax.swing.*;
import java.text.*;
public class CardDeck
public CardDeck()
deck = new Card[52];
fill();
shuffle();
public void fill()
int i;
int j;
for (i = 1; i <= 13; i++)
for (j = 1; j <= 4; j++)
deck[4 * (i - 1) + j - 1] = new Card(i, j);
cards = 52;
public void shuffle()
int next;
for (next = 0; next < cards - 1; next++)
int rand = (int)(Math.random()*(next+1));
Card temp = deck[next];
deck[next] = deck[rand];
deck[rand] = temp;
public final Card draw()
if (cards == 0)
return null;
cards--;
return deck[cards];
public int changeValue()
int val = 0;
boolean ace = false;
int cds;
for (int i = 0; i < cards; i++)
if (cardValue > 10)
cardValue = 10;
if (cardValue ==1) {
ace = true;
val = val + cardValue;
if ( ace = true && val + 10 <= 21 )
val = val + 10;
return val;
public static void main(String[] args)
CardDeck d = new CardDeck();
int x = 3;
int i;
int wins = 1;
int playerTotal = 1;
do {
Card dealer = (d.draw());
/**I've tried everything I can think of to call the ChangeValue() method after I draw the card, but nothing is working for me.**/
System.out.println("Dealer draws: " + dealer);
do {
dealer = (d.draw());
System.out.println(" " + dealer);
}while (dealer.rank() <= 17);
Card mine = d.draw();
System.out.println("\t\t\t\t Player draws: "
+ mine);
mine = d.draw();
System.out.println("\t\t\t\t\t\t" + mine);
do{
String input = JOptionPane.showInputDialog
("Would you like a card? ");
if(input.equalsIgnoreCase("yes"))
mine = d.draw();
System.out.println("\t\t\t\t\t\t" + mine);
playerTotal++;
else if(input.equalsIgnoreCase("no"))
System.out.println("\t\t\t\t Player stands");
else
System.out.println("\t\tInvalid input.
Please try again.");
I don't know how to go about making and calling a method or class that will combine the total cards delt to the player and the total cards delt to the dealer. The rank() method only seems to give me the last cards drawn to compare with when I try to do the tests.**/
if ((dealer.rank() > mine.rank())
&& (dealer.rank() <= 21)
|| (mine.rank() > 21)
&& (dealer.rank() < 22)
|| ((dealer.rank() == 21)
&& (mine.rank() == 21))
|| ((mine.rank() > 21)
&& (dealer.rank() <= 21)))
System.out.println("Dealer wins");
wins++;
else
System.out.println("I win!");
break;
} while (playerTotal <= 1);
String stop = JOptionPane.showInputDialog
("Would you like to play again? ");
if (stop.equalsIgnoreCase("no"))
break;
if (rounds == 5)
System.out.println("Player wins " +
(CardDeck.rounds - wins) + "rounds");
} while (rounds <= 5);
private Card[] deck;
private int cards;
public static int rounds = 1;
public int cardValue;
/**When I try to compile this nested class, I get an error message saying I need a brace here and at the end of the program. I don't know if any of this code would work because I've tried adding braces and still can't compile it.**/
class Hand()
static int r = 1;
public Hand() { CardDeck.rounds = r; }
public int getRounds() { return r++; }
final class Card
public static final int ACE = 1;
public static final int JACK = 11;
public static final int QUEEN = 12;
public static final int KING = 13;
public static final int CLUBS = 1;
public static final int DIAMONDS = 2;
public static final int HEARTS = 3;
public static final int SPADES = 4;
public Card(int v, int s)
value = v;
suit = s;
public int getValue() { return value; }
public int getSuit() { return suit; }
public int rank()
if (value == 1)
return 4 * 13 + suit;
else
return 4 * (value - 1) + suit;
/**This works, but I'm confused. How is this method called? Does it call itself?**/
public String toString()
String v;
String s;
if (value == ACE)
v = "Ace";
else if (value == JACK)
v = "Jack";
else if (value == QUEEN)
v = "Queen";
else if (value == KING)
v = "King";
else
v = String.valueOf(value);
if (suit == DIAMONDS)
s = "Diamonds";
else if (suit == HEARTS)
s = "Hearts";
else if (suit == SPADES)
s = "Spades";
else
s = "Clubs";
return v + " of " + s;
private int value; //Value is an integer, so how can a
private int suit; //string be assigned to an integer?
}Thank you so much for offering to help me with this Jamie! When I tried to call change value using:
Card dealer = (d.changeValue());
I get an error message saying:
Incompatible types found: int
required: Card
I had my weekly class last night and the professor cleared up a few things for me, but I've not had time to make all of the necessary changes. I did find out how toString worked, so that's one question out of the way, and he gave us a lot of information for adding another class to generate random numbers.
Again, thank you so much. I really want to learn this but I'm feeling so stupid right now. Any help you can give me about the above error message would be appreciated. -
New to java: how to replace an image extending a JComponent?
Hi,
I'm new to Java and I have a question about Swing:
I have a class called ActiveImage (entends JComponent, implements MouseMotionListener, MouseWheelListener) which takes an Image and displays it. It also receives some mouse events for zooming and moving it around. I display it in a JFrame using:
content = getContentPane();
content.setLayout(new BorderLayout());
image = toolkit.getImage (filename);
ActiveImage activeImage = new ActiveImage(image);
content.add(activeImage, BorderLayout.CENTER);
(This code is in a class extending JFrame.)
This works fine. However, this JFrame also contains a JToolbar with two buttons. Now when I click one of them, I want to replace the image with another one. I've tried removing it and creating a new ActiveImage to add that to content, but that didn't work very well. remove() resulted in a NullPointerException.
My question: what would be the best way to go about this?
Many thanks for any help,
Diederick de VriesB.T.W., this is the trace:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at ActiveImage.ActiveImageFrame$1.actionPerformed(ActiveImageFrame.java:60)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1849)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2169)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:234)
at java.awt.Component.processMouseEvent(Component.java:5488)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3093)
at java.awt.Component.processEvent(Component.java:5253)
at java.awt.Container.processEvent(Container.java:1966)
at java.awt.Component.dispatchEventImpl(Component.java:3955)
at java.awt.Container.dispatchEventImpl(Container.java:2024)
at java.awt.Component.dispatchEvent(Component.java:3803)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
at java.awt.Container.dispatchEventImpl(Container.java:2010)
at java.awt.Window.dispatchEventImpl(Window.java:1766)
at java.awt.Component.dispatchEvent(Component.java:3803)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:234)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)Just before this, it says "button clicked". The function that calls the setImage() goes:
theButton.addActionListener (new ActionListener() {
public void actionPerformed(ActionEvent ae) {
System.out.println("button clicked");
activeImage.setImage(image);
});Reading the trace, I would think that the exception has something to do with this last code, since it stops there (line 60 is the setImage()). If the setImage() function itself was where the fault was, wouldn't the trace end there?
I'm really at a loss here ... :-( -
Hi, I have moved to India from france and I am trying to update my payment options to the Indian visa card but it seems that no matter what I do I cant do it. I dont want to create a new ID..Plz Help!!!Just want to change my location and my payment details!! thanks in advance!!
These are two possible approaches that will normally work to move an existing library to a new computer.
Method 1
Backup the library with this User Tip.
Deauthorize the old computer if you no longer want to access protected content on it.
Restore the backup to your new computer using the same tool used to back it up.
Keep your backup up-to-date in future.
Method 2
Connect the two computers to the same network. Share your <User's Music> folder from the old computer and copy the entire iTunes library folder into the <User's Music> folder on the new one. Again, deauthorize the old computer if no longer required.
Both methods should give the new computer a working clone of the library that was on the old one. As far as iTunes is concerned this is still the "home" library for your devices so you shouldn't have any issues with iTunes wanting to erase and reload.
I'd recommend method 1 since it establishes an ongoing backup for your library.
Note if you have iOS devices and haven't moved your contacts and calendar items across then you should create one dummy entry of each in your new profile and iTunes should merge the existing data from the device.
If your media folder has been split out from the main iTunes folder you may need to do some preparatory work to make it easier to move. See make a split library portable.
Should you be in the unfortunate position where you are no longer able to access your original library or a backup then then seeRecover your iTunes library from your iPod or iOS device for advice on how to set up your devices with a new library with the maximum preservation of data.
tt2
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