将jTable与MySQL数据库连接时，Java Net bean IDE 8.0中的数组越界异常

Question

I have a table with 7 columns and I'm trying to connect my database with it so as to receive data from the database and show it in the table. The code works fine when you press the button the first time but when you press it a second time, the table becomes blank and i get this error:

java.lang.ArrayIndexOutOfBoundsException: 0 >= 0

I have given my code below for the ActionPerformed method of the button.

try
{
    Class.forName("com.mysql.jdbc.Driver");
    Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/db_name","root","admin123");
    String query="SELECT * FROM tablename;";
    Statement st = con.createStatement();
    ResultSet rs= st.executeQuery(query);


    DefaultTableModel tmodel = (DefaultTableModel) jTable1.getModel();


    int rows=tmodel.getRowCount();
    while(rows>0)
    {
        tmodel.removeRow(0);
    }
    jTable1.setModel(tmodel);

while(rs.next())
{

    tmodel.addRow(new Object[] {rs.getInt("column1"),rs.getString("Column2"),rs.getString("Column3"),rs.getInt("Column4"),rs.getString("Column5"),rs.getString("Column6"),rs.getString("Column7")});
    jTable1.setModel(tmodel);
}

}
catch(Exception ex)
{
    System.out.println("Eception: "+ex);
}

Any help would be greatly appreciated.

Answer 1

Since you never update rows inside the loop, the while will keep going forever or until an Exception is reached...

            while(rows>0)
            {
                tmodel.removeRow(0);
            }

And of course, setRowsCount() will be way simpler and less error prone.

BTW: Helping you would be easier if you pointed which line was the one throwing the exception.

Answer 2

your problem is with this part although it is a relatively simple fix:

            int rows=tmodel.getRowCount();
            while(rows>0)
            {
                tmodel.removeRow(0);
            }
            jTable1.setModel(tmodel);

what you want to do is:

            while(tmodel.getRowCount()>0)
            {
                tmodel.removeRow(0);
            }
            jTable1.setModel(tmodel);

because you are setting a variable to a constant value returned by the method which means it wont be updated as you continue to delete rows