Vector Class

Hi i can't work out why when i compile this program, i get "warnings"
how do i fix this?
Thanks guys & gals
Sarah :)
Vector invent = new Vector();
        System.out.println(invent.capacity());
        invent.addElement(7);
        invent.add("piuyytt");
        System.out.println(invent.firstElement());
        System.out.println(invent.lastElement());
        Warnings i get:
2 warnings found:
File: /Users/Benji/Tutortial:Lab 1 - Week 2/A.java [line: 28]
Warning: [unchecked] unchecked call to addElement(E) as a member of the raw type java.util.Vector
File: /Users/Benji/Tutortial:Lab 1 - Week 2/A.java [line: 29]
Warning: [unchecked] unchecked call to add(E) as a member of the raw type java.util.Vector

2 warnings found:
File: /Users/Benji/Tutortial:Lab 1 - Week 2/A.java
[line: 28]
Warning: [unchecked] unchecked call to addElement(E)
as a member of the raw type java.util.Vector
File: /Users/Benji/Tutortial:Lab 1 - Week 2/A.java
[line: 29]
Warning: [unchecked] unchecked call to add(E) as a
member of the raw type java.util.VectorAre you aware of Java Generics?
http://java.sun.com/developer/JDCTechTips/2005/tt0315.html
Thank you. -Ronillo

Similar Messages

Where is the Vector class? Can't use it.

Hello!
I've downloaded Flex Builder 3 Trial from Adobe's website.
Now I want to use the Vector class, but this code for example:
var v:Vector.<String>;
v = new Vector.<String>();
Gives me this error:
1046: Type was not found or was not a compile-time constant: Vector.
At the IDE, going to
Window -> Preferences -> Flex -> Installed Flex SDKs
I can see that I have Flex 3.2 SDK.
Even more than that: When I search for "Vector" in the help ("Adobe® Flex™ 3 Language Reference") I can see all the details about Vector.
What can I do?
I'd like to avoid installing any newer SDKs due to all the bugs I see listed here in the forums.
Thank you!

It looks like you are trying to type Java code in Flex Builder. Flex applications are generally built using ActionScript.
These docs might help you learn ActionScript:
http://www.flexafterdark.com/docs/ActionScript-Language
http://www.flexafterdark.com/docs/ActionScript-vs-Java
I hope that helps...
Ben Edwards

Regarding Vector classes in JSP

Hello,
Where we actually use the vector classes in jsp page.Is there any necessary to use Vector classes in jsp programs instead of database.Or is there any conditions like here we have use vector instead of DataBase.

JSP pages are part of the "view" layer in the MVC design pattern.
As such, it is advisable to seperate them from the model/control layer. For this reason, database code in a JSP page is undesirable.
The controller normally queries the model, places the results into a collection/vector, makes them available to the jsp page. All the jsp page knows is that it gets the collection - nothing about where it came from or how the model is accessed.
It is not NECESSARY to do so. You can easily put SQL statements, and scriptlets into your JSP pages. But keeping that stuff out makes for more easily understood and maintainable web applications.
Cheers,
evnafets

Need help about Vector class in java

Hello,
I have some questions about Vector class. Please see this short code:
Vector v = new Vector();
v.add(New Integer(5));
Is this the only way to add int value into vector? Performance wise, is this slow? And are there any better and faster way to add/get int element fro vector?
Thank you very much in advance.

Normally (up to Java version 1.4), that's the only way you can add an int to a Vector. The thing is that Vector can only contain Objects, and an int is a primitive, not an object. So you have to wrap the int in an Integer object.
However, Java 5 has a new feature, called autoboxing, which means that the compiler automatically wraps primitive values into objects, so that you can program it like this:
Vector v = new Vector();
v.add(5);Note, this will not make your program faster or more efficient, because the compiler translates this automatically to:
Vector v = new Vector();
v.add(new Integer(5));So in the end, the same bytecode will be produced. Autoboxing is just a feature to make life more convenient for the programmer.

How can I extend the Vector class?

Hi All,
I'm trying to extend the Vector class so I can get add a .remove(item:T) method to the class. I've tried this:
public class VectorCollection extends Vector.<T>
That gives me the compile error "1017: The definition of base class Vector was not found"
So then I tried:
public class VectorCollection extends Vector
Which gives me the compile error "1016: Base class is final."
There must be some way to extend the Vector class, though, as on the Vector's official docs page it says:
Note: To override this method in a subclass of Vector, use ...args for the parameters, as this example shows:
public override function splice(...args) {
// your statements here
So there must be a way to extend the Vector class. What am I doing wrong?

No. AS3 doesn't currently have full support for generic types; Vector.<T> was added in an ad-hoc ("ad-hack"?) way. We are considering adding full support in a future version of ActionScript.
Gordon Smith
Adobe Flex SDK Team

The get() of Vector class, is it thread safe??

Hi all:
the get() of Vector class, is it thread safe?? I looked into the API, but no info is available, so any help is appreciated

You just have to look out when you perform two or more methods on the Vector in sucession. Then it's better to lock on the vector itself. If you for instance access the vector to query whether the size is greater than zero and immediately remove an item while another thread is removing elements from the same vector, you might get a dirty read and call get() on the vector while there are no elements left.

Flex 3 : How to import Vector Class ?

Hi,
I'm using Flex Builder3.
And I'm trying to use the new Vector Class (the typed array : http://help.adobe.com/en_US/FlashPlatform/beta/reference/actionscript/3/Vector.html)
But it seems that it's not available.
I probably have to update something... but what? the sdk?
thanks for your advices

I've updated to sdk 3.4, but still I have a message saying that the compiler cannot find the type Vector
I'm trying to do this...
package{
    public class test{
        private var v:Vector.<String>;
        public function test(){
            v = new Vector.<String>();

Can someone explain to me Vector Class !!

Can someone explain to me, or tell me where I can find a good tutorial about Vector class.....in simple terms....any good simple, easy to understand tutorials???
Thank you.
Rod

Start with this:
http://java.sun.com/j2se/1.4/docs/api/java/util/Vector.html
Essentially, a vector is a single Java object that allows you to store a group of similar things. Each item, or element, inside the Vector must be of the same type, or Java class. The important thing to remember about Vectors is that their size is not fixed. If you don't know how many items you need to store in advance, a Vector is a useful datastore, because you can simply add items into it without worrying about reaching the maximum size. The Vector object will grow itself as you add elements.
The important methods are described in the above API. Read through it carefully.

Vector class warning

i am learning to use the vector class. i am getting this warning but the program still runs:
warning: [unchecked] unchecked call to addElement(E) as a member of the raw type java.util.Vector
heres the code:
int a=0;
Vector i=new Vector();
i.addElement(a);//this is the line causing the warning
System.out.println(i.elementAt(0));why is the compiler returning this warning but still allowing the program to run?

Getting back to the original quesiton......
After you do some research on generics, try to get rid of all those warnings by implementing generics properly in your code. Its not hard once you correct a few such problems and see how its done.
Although you don't have to correct them since they are only warnings, its good practice since seeing 100 generics warnings may hide other types of warnings you should really look into. Note you can't always get rid of the warnings since generics aren't backwardly compatable with certain java classes (such as ArrayList.toArray()?). To hide these warnings, put @suppressWarnings("unchecked") above the function you want to hide those warnings.
suppressWarnings will only work for jdk 1.5 and later(?).
By the way, your code has i.addElement(a) where a is an integer. You might want to read up on autoboxing since java converts this int to an Integer.
Edited by: njb7ty on May 31, 2008 4:36 PM

Vector class size limitation

Hi guys,
Does anyone know how big a Vector class can be?
I'm planning to have a Vector object of size ~200,000 to 500,000 elements.
I would really want to use the vector in my design and benefit from its sync feature. The only concern is how reliable it will be..
Has anyone have an idea?
Thanks!

Shouldn't that response be qualified? Somethinglike,
where your datastructure doesn't need to be thread
safe, use an ArrayList? I thought that was theonly
real reason to use ArrayList over Vector. Arethere
other reasons? Anyhow, his answer to your questionis
correct, afaik.If you need synchronization... use ArrayList and the
Collections.synchronizedList() method. Vector has too
many non-List methods.
I still say that is wrong, if your data structure needs to be thread safe, then you should use the synchronize on it where ever you use it.
Is this code thread safe?
Vector memberVector = new Vector();
public void addToVector(Object c, Class cType ) {
memberVector.add( c );
memberVector.add(cType);
}This should produce a vector with alternating objects and then a class that is associated with that object. However, will this code always work?
The answer is no, even though the vector is 'thread safe' this operation is not. If 2 threads call this function on the same instance of the object, then you can get a situation where 2 objects appear in the list one after another. or 2 classes, it really depends on the thread task scheduler. The only difference between this and an ArrayList is that if you had used an ArrayList the internal structure might get messed up and you might get only one of the objects, and 2 classes or some other combination.
So the answer to this problem is this
Vector memberVector = new Vector();
public void addToVector(Object c, Class cType ) {
synchronized ( memberVector ) {
memberVector.add( c );
memberVector.add(cType);
}You must sync on the member vector, but in this case, syncing on 'this' would work as well assuming that you used data encapsulation.
I can't 'prove' it, but if you use proper syncing, then Vector, or any 'thread safe' data structure is no better then a non-thread safe version. It may be that it's easier to debug (sometimes) when dealing with vectors, since no elements will accidently be overwritten ,etc. But it's still unsafe.

Vector class can't be resolved

hi ,
plz i got the following error while running a J2ME
program
cannot resolve symbol
symbol : method add (java.lang.String)
location: class java.util.Vector
any ideas????

The name of the method is addElement(). A quick glance at the javadocs would have solved that problem in no time.
shmoove

Send Vector class to JSP and print this Vector using JSTL

Hello All!
I need your help to solve my question.
I developed a Servlet + jsp application.
I tested it in local with Apache Tomcat/6.0.20 and it works correctly.
I write and use these classes:
class for execute query, and including data page:
package MySQL;
* To change this template, choose Tools | Templates
* and open the template in the editor.
import java.util.*;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
* @author initmax
public class MySQLQuery {
    private Connection CurrentConnect; //obj for connect to databae
    private Vector VectorPageObj = new Vector(); //save array object page, after execute query
public MySQLQuery() {}
//constructor accept current conection database
public MySQLQuery(Connection CurrentConnectBase)
    CurrentConnect = CurrentConnectBase;
//method accept name table and return all info on this table
public void SelectAllField(String NameTable)
       try
         Statement st = CurrentConnect.createStatement();
         String query = ("select * from "+NameTable);
         ResultSet resultQuery = null;
         resultQuery = st.executeQuery(query);
//step in cycle after execution query, and create Vector object
           while (resultQuery.next())
              GenPageMySQL PageObj = new GenPageMySQL();
              PageObj.setId(resultQuery.getInt("id"));
              PageObj.setTheme(resultQuery.getString("theme"));
              PageObj.setPage(resultQuery.getString("page"));
              VectorPageObj.add(PageObj); //add obj in tail vector
       catch (SQLException e) {
         e.printStackTrace();
    *@set the CurrentConnect
    public void setConnection(Connection CurrentConnectBase) {
         CurrentConnect = CurrentConnectBase;
    *@get Vector object "Vector created after execute query"
     public Vector getVectorPageObj(Connection CurrentConnectBase) {
         return VectorPageObj;
}start Servlet class:
import java.util.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import MySQL.*;
public class indexServlet extends HttpServlet {
    private String getpage;
    //Connected MySQL
    private MySQLConnect MySQLConnectObj = new MySQLConnect();
    private MySQLQuery MySQLQueryObj = new MySQLQuery();
    public void init(){
          MySQLConnectObj.DownloadDriver();
          MySQLConnectObj.Connected();
          //Use current connection, for execution query
          MySQLQueryObj.setConnection(MySQLConnectObj.GetConnection());
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException, NullPointerException {
//      init();
        PrintWriter out = response.getWriter();
//GET case useer
      getpage = request.getParameter("page");
      out.print("MySQLConnectObj.GetConnection() = "+MySQLConnectObj.GetConnection());
//Check curent connect to database
      if(MySQLConnectObj.GetConnection() != null)
           MySQLQueryObj.SelectAllField("up_menu");//execution query
           MySQLConnectObj.DisConnected();
            request.setAttribute("up_menu_theme",MySQLQueryObj.getVectorPageObj(null));
            RequestDispatcher Dispatcher = getServletContext().getRequestDispatcher("/WEB-INF/jsp/index.jsp");
            Dispatcher.forward(request, response);
      else if(MySQLConnectObj.GetConnection() == null){
            init() ;
        out.print("MySQLConnectObj.GetConnection() = "+MySQLConnectObj.GetConnection());
//        MySQLConnectObj.DisConnected();
}I forward Vector "MySQLQueryObj.getVectorPageObj(null)" to JSP, how I can print data vector using JSTL?

your right, I learn Java however this very Interesting!
I change code, change Vector on List
class MySQLQyery:
package MySQL;
* To change this template, choose Tools | Templates
* and open the template in the editor.
import java.util.*;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
* @author initmax
public class MySQLQuery {
    private Connection CurrentConnect; //obj for connect to databae
public MySQLQuery() {}
//constructor accept current conection database
public MySQLQuery(Connection CurrentConnectBase) {
    CurrentConnect = CurrentConnectBase;
//method accept name table and link on List, after work return all info on this table inside List
public List<GenPageMySQL> selectAllField(String NameTable, List<GenPageMySQL> ListPageObj) {
       try {
         Statement st = CurrentConnect.createStatement();
         String query = ("select * from "+NameTable);
         ResultSet resultQuery = null;
         resultQuery = st.executeQuery(query);
//step in cycle after execution query, and create Vector object
           while (resultQuery.next()) {
              GenPageMySQL PageObj = new GenPageMySQL();
              PageObj.setId(resultQuery.getInt("id"));
              PageObj.setTheme(resultQuery.getString("theme"));
              PageObj.setPage(resultQuery.getString("page"));
              ListPageObj.add(PageObj); //add obj in tail vector
       catch (SQLException e) {
         e.printStackTrace();
       return ListPageObj;
    *@set the CurrentConnect
    public void setConnection(Connection CurrentConnectBase) {
         CurrentConnect = CurrentConnectBase;
List<GenPageMySQL> ListPageObj;
            //get List<RowObject>
            ListPageObj = MySQLQueryObj.getListPageObj();
out.print("Size Page objects = "+ListPageObj.size());
            request.setAttribute("upMenu",ListPageObj);
            RequestDispatcher Dispatcher = getServletContext().getRequestDispatcher("/WEB-INF/jsp/index.jsp");
            Dispatcher.forward(request, response);string out.print("Size Page objects = "+ListPageObj.size()); == worked, I get count objects correct
How I can output fields Object GenPageMySQL in JSTL?
writing so:
         <c:out value="hello, Max" />
         <c:out value="${10+20/2}" />
         <c:forEach items="${upMenu}" var="Object" >
               <c:out value="${Object.getId}"> </c:out>
         </c:forEach>
    </body>
</html>but get error:
org.apache.jasper.JasperException: An exception occurred processing JSP page /WEB-INF/jsp/index.jsp at line 36
33:          <c:forEach items="${upMenu}" var="Object" >
34:
35:
36:                <c:out value="${Object.getId}"> </c:out>
37:
38:
39:          </c:forEach>
Stacktrace:
     org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:505)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
     indexServlet.doGet(indexServlet.java:49)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:717)How I can in output print fields my Object?
Thank you for your help.

NullPointerException when adding an object into a Vector Class

So here is the code:
package Image;
import java.io.Serializable;
import java.util.Vector;
public class Album implements Serializable{
private String name;
private String password;
Vector<ImageClass> allImages;
public Album( String name, String password, Vector<ImageClass> allImages) {
this.name = name;
this.password = password;
this.allImages = allImages;
public Album() {
public Vector<ImageClass> getAllImages() {
return allImages;
public void setAllImages(Vector<ImageClass> allImages) {
this.allImages = allImages;
public String getName() {
return name;
public void setName(String name) {
this.name = name;
public String getPassword() {
return password;
public void setPassword(String password) {
this.password = password;
public void addIC(ImageClass ic){
allImages.add(ic);
public ImageClass getIC(int pos){
ImageClass ic = allImages.get(pos);
return ic;
Now I got an NullPointerException when I call the getIC Method from another class of another package
Here is the part of code of that class.
private void SaveMenuItemActionPerformed(java.awt.event.ActionEvent evt) {
ImageClass ic = new ImageClass();
ic.setTitle(ImageTextField.getText());
ic.setDescription(DescriptionTextArea.getText());
try {
ic.setReferenceNumber(Integer.parseInt(ReferenceTextField.getText()));
} catch (NumberFormatException nfe) {
JOptionPane.showMessageDialog(null, "Reference Number is not in a correct format");
try {
ic.setDate(new SimpleDateFormat("dd/MM/yyyy").parse(DateTextField.getText(), new ParsePosition(0)));
} catch (IllegalArgumentException iae) {
JOptionPane.showMessageDialog(null, "Date is not in correct format");
ic.setImageData(imageData);
if(a==null){
JOptionPane.showMessageDialog(this,"Please, create or open an Album");
}else{
a.addIC(ic);
try{
ObjectOutputStream oos;
FileOutputStream fos = new FileOutputStream(album, true);
oos = new ObjectOutputStream(fos);
oos.writeObject(a);
oos.flush();
oos.close();
}catch(FileNotFoundException fnfe){
fnfe.printStackTrace();
}catch(IOException ioe){
ioe.printStackTrace();
}

h1. The Ubiquitous Newbie Tips
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    (d) read the relevant section of the [API Docs|http://java.sun.com/javase/6/docs/api/index-files/index-1.html] and maybe even
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* [Good questions|http://www.catb.org/~esr/faqs/smart-questions.html#intro] get better Answers. It's a fact. Trust me on this one.
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      - FFS spare us the SMS and L33t speak! Pull your pants up, and get a hair cut!
    - Often you discover your own mistake whilst forming a "Good question".
    - Often you discover that you where trying to answer "[the wrong question|http://blog.aisleten.com/2008/11/20/youre-asking-the-wrong-question/]".
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      especially to a nuggetty problem, because they're interested in the answer.
* Improve your chances of getting laid tonight by writing an SSCCE
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We the New To Java regulars do hereby pledge to refrain from flaming anybody, no matter how gumbyish the question, if the OP has demonstrably tried to cover these bases. The rest are fair game.

The Vector class

The vector is it deprecated?
Because some of me friends said yes, and some no!

No. Officially it is not deprecated.
However the introduction of the Collections framework have provided superior tools to Vector.
If all you want is a dynamic array (which is essentially what it was used for) the main recommendation is to use ArrayList as it is exactly the same functionality, but has a faster implementation.
So in that sense, most places you originally wanted to use Vector, you should instead use ArrayList. Also is you look in the Collections framework documentation, it is listed as a Legacy class.
But no, Vector has not been officially deprecated.

Vector class, insertElementAt() method and JComboBox

Hi guys,
I am using a vector called vectorSquare. I have an (Square)object in each component. When I run the program, depending on how many squares the user chooses, the combobox size will be vectorSquare.size(). Everything is all right. But if the user reenter data for one of the square, I think the vectorSquare.size() increases 1. Using vSquares.insertElementAt(temp, comboBox.getSelectedIndex()); when the user enters the data works OK, but if the user wants to change and reenter the data of a square, the new solution will be through the getSelectedIndex()) giving by the JComboBox. Instead, the past result will keep displaying, in getSelectedIndex() + 1 index. I don't know why. I thought insertElementAt() inserts new data but delete the past one, but it doesn't seem at all. Thats why I have decided to delete the past entering. But doing that, it compiles but now doesn't run, and gives an error to me here:
--> if (vSquares.elementAt(comboBox.getSelectedIndex()) != null) {
At the beginning I used:
vSquares.insertElementAt(temp, comboBox.getSelectedIndex());
But it overwrites, so I now use this:
if (vSquares.elementAt(comboBox.getSelectedIndex()) != null) {
vSquares.removeElementAt(comboBox.getSelectedIndex());
vSquares.insertElementAt(temp, comboBox.getSelectedIndex());
But it doesnt run as I said above.
Anybody knows what I could do to work it out?
Thank you.

Hi, its me again. I am checking and it still doesn't work. I have tried these different ways and I dont know whats going on??????
vSquares.insertElementAt(temp,comboBox.getSelectedIndex());
vSquares.removeElementAt(comboBox.getSelectedIndex()+1);
++++++++++++++++++++++
vSquares.setElementAt(temp,comboBox.getSelectedIndex());
/++++++++++++++++++++
int p = comboBox.getSelectedIndex();
vSquares.removeElementAt(p);
vSquares.insertElementAt(temp,p);
++++++++++++++++++++++++
int p = comboBox.getSelectedIndex();
vSquares.setElementAt(temp,p);

Vector Class

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