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Thread: Causing NULL POINTER when i add a code;

  1. #1
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    Post Causing NULL POINTER when i add a code;

    public DefaultTableModel showTable(DefaultTableModel tmodel, String sql){
            DefaultTableModel tm = tmodel;
            String sq = sql;
     
     
           try {
               st=con.createStatement();
               rs=st.executeQuery(sq);
               System.out.println("Query: "+sq);
     
               ResultSetMetaData rmeta = (ResultSetMetaData)rs.getMetaData();
               int numColumns = rmeta.getColumnCount();
               System.out.println("Column Count: "+numColumns);
     
               for(int i=1;i<=numColumns;i++){
                   if(i<=numColumns){
                       System.out.println(rmeta.getColumnName(i));
                       tm.addColumn(rmeta.getColumnName(i));
                   } 
               }
     
     
     
           } catch (SQLException ex) {
               Logger.getLogger(JDBCCrud.class.getName()).log(Level.SEVERE, null, ex);
           }
     
     
     
        return tm;
        }//SHOWTABLE



    when i add: tm.addColumn(rmeta.getColumnName(i));
    the program will show errors which says that it was a NULL POINTER and lead me to this code.

    im getting the name of column to the database. and i used this code: System.out.println(rmeta.getColumnName(i)); to check if java gets the data from sqlserver database.


  2. #2
    Member coderxx0's Avatar
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    Default Re: Causing NULL POINTER when i add a code;

    Quote Originally Posted by ZDreamer08 View Post
    public DefaultTableModel showTable(DefaultTableModel tmodel, String sql){
            DefaultTableModel tm = tmodel;
            String sq = sql;
     
     
           try {
               st=con.createStatement();
               rs=st.executeQuery(sq);
               System.out.println("Query: "+sq);
     
               ResultSetMetaData rmeta = (ResultSetMetaData)rs.getMetaData();
               int numColumns = rmeta.getColumnCount();
               System.out.println("Column Count: "+numColumns);
     
               for(int i=1;i<=numColumns;i++){
                   if(i<=numColumns){
                       System.out.println(rmeta.getColumnName(i));
                       tm.addColumn(rmeta.getColumnName(i));
                   } 
               }
     
     
     
           } catch (SQLException ex) {
               Logger.getLogger(JDBCCrud.class.getName()).log(Level.SEVERE, null, ex);
           }
     
     
     
        return tm;
        }//SHOWTABLE



    when i add: tm.addColumn(rmeta.getColumnName(i));
    the program will show errors which says that it was a NULL POINTER and lead me to this code.

    im getting the name of column to the database. and i used this code: System.out.println(rmeta.getColumnName(i)); to check if java gets the data from sqlserver database.
    is this the same code as this?

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    Default Re: Causing NULL POINTER when i add a code;

    no. im disecting my code. so i found the error and it was in the tm.addColumn(rmeta.getColumnName(i));

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    Member coderxx0's Avatar
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    Default Re: Causing NULL POINTER when i add a code;

    Quote Originally Posted by ZDreamer08 View Post
    no. im disecting my code. so i found the error and it was in the tm.addColumn(rmeta.getColumnName(i));
    ok have you fixed it? or still need assistance?

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    Default Re: Causing NULL POINTER when i add a code;

    still need assistance and as i debug it. i have a bad feeling that it's because of the DefaultTableModel tm; is being the NULL POINTER error. cause when im getting the row information from database, it has the error NULL POINTER too that goes to tm.addRow(data);

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    Default Re: Causing NULL POINTER when i add a code;

    Are you sure the table model isn't null when being passed in?

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    Super Moderator jps's Avatar
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    Default Re: Causing NULL POINTER when i add a code;

    For faster and likely more useful replies, include the full text of the error message(s) with the code and your question

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