CODEWITHSUNDEEP
javaarraysstringindexoutofboundsexception
Paras Dhawan
Paras Dhawan

Reputation: 374

array index out of bound

I want to create a combobox which takes names from database at runtime. So i created a empty string array but it throws an exception that arrayindexoutofbound. I think there's a mistake in initialization..... 

            String s[]=new String[0];
            {
                 try
                {
                  Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
                  Connection con =DriverManager.getConnection("jdbc:odbc:project","sa","123456");
                  Statement stmt= con.createStatement();
                  ResultSet rs=stmt.executeQuery("SELECT Name FROM company");
                  i=0;
                  while(rs.next()) {        
                        s[i]=rs.getString(1);
                        i++;
                  }
                }
                catch(Exception ex)
                {
                    JOptionPane.showConfirmDialog(f,ex);
                }
                cb=new JComboBox(s);
            }

Upvotes: 0

Views: 2994

Answers (4)

mmratxs
mmratxs

Reputation: 86

I am also working on a project getting data from database and adding it to a combobox, I prefer you to take it simple, there is no need to create an array, you just simply write:

 try
            {
              Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
              Connection con = DriverManager.getConnection("jdbc:odbc:project","sa","123456");
              Statement stmt= con.createStatement();
              ResultSet rs=stmt.executeQuery("SELECT Name FROM company");
              cb=new JComboBox();
              while(rs.next()) {   
                    cb.addItem(rs.getString(1));
              }
            }
            catch(Exception ex)
            {
                JOptionPane.showConfirmDialog(f,ex);
            }

Note: If you want to save data first and then add it to combobox, you should use Vector instead of array because it has limitation u will defined as told by

The New Idiot

Upvotes: 1

mmratxs
mmratxs

Reputation: 86

You can also use Vector List:

 {

  Vector<String> namesList;

  try
        {
          Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
          Connection con = DriverManager.getConnection("jdbc:odbc:project","sa","123456");
          Statement stmt= con.createStatement();
          ResultSet rs=stmt.executeQuery("SELECT Name FROM company");
          namesList = new Vector<>();

          while(rs.next()) {
                namesList.add(rs.getString(1));
          }
        }
        catch(Exception ex)
        {
            JOptionPane.showConfirmDialog(f,ex);
        }
        cb=new JComboBox(namesList);
 }

Upvotes: 1

AllTooSir
AllTooSir

Reputation: 49432

An array is a container object that holds a fixed number of values of a single type. The length of an array is established when the array is created. After creation, its length is fixed. You are creating an array to hold 0 elements .

String s[]=new String[0]; //<< intialized with length 0

It will throw ArrayindexoutOfBoundsException when you try to access its 1st element s[0].

Thrown to indicate that an array has been accessed with an illegal index. The index is either negative or greater than or equal to the size of the array.

Size the size of your array is 0 , hence Exception is thrown while accessing index 0.

Below a basic diagram of an array for understanding.

enter image description here

It is an array of length 10 , indexed from 0 to 9.

Since you don't know the number of elements your data structure needs to store while declaring the array itself. It is better to use a dynamic Collection in your case , probably any one of the implementation of List , like an ArrayList.

List<String> s = new ArrayList<String>();
while(rs.next())
{
   s.add(rs.getString("NAME")); // using column name instead of index "1" here
}

Suggested Reading:

  1. Oracle's tutorial on Java arrays
  2. Lists vs Arrays - when to use what

Upvotes: 10

DRastislav
DRastislav

Reputation: 1882

You created array with length 0. If u know how many members you need use array, if u dont know is better to use ArrayList

Upvotes: 1

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