Solved

Display a result set in a TextArea

Posted on 1998-10-11
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1,307 Views
Last Modified: 2012-08-13
Can anybody help me to correct and improve the following program? I use JDK1.1.6.
I want to display all columns and rows of the given result set in
a textArea when the user selects the item "View"->"Report"->
"Students". Also, each report should have a Title and
date. For example:
                       
                   Student's Report
Oct. 10, 1998

FirstName       LastName      Course       Grade
---------------------------------------------------------------------



import java.awt.*;
import java.awt.event.*;
import java.sql.*;

public class ReportsFrame extends Frame implements ActionListener
{  
   static TextArea t;
   DataQuery q;
   ReportHandler reportHandler;

   public ReportsFrame(String s)
   {  
       super(s);
       setTitle( "Reports" );
       setSize(700, 450);
       MenuBar mbar = new MenuBar();
     
       Menu ViewMenu = new Menu( "View" );
       Menu report = new Menu( "Report" );  
       MenuItem r1 = new MenuItem("Students");
       r1.addActionListenter(reportHandler);
       report.add(r1);
      ViewMenu.add(report);

       setMenuBar(mbar);
       t = new TextArea();
       t.setEditable(false);
       add("Center", t);
       
     
       //{{REGISTER_LISTENERS
       this.addWindowListener(new WindowAdapter(){
           public void windowClosing(WindowEvent e){
                 dispose();
                 setVisible(false);}
       });
    }

    protected void showResultSet(ResultSet rs) throws SQLException{
     
       int i;
       //Get the ResultSetMetaData. This will be used for
       //the column headings

       ResultSetMetaData rsmd = rs.getMetaData();
       //Get the number of columns in the result set
       int numCols = rsmd.getColumnCount();
       //Display column headings
       for( i = 1; i<=numCols; i++){
           if(i> 1) System.out.print("  ");
           System.out.print(rsmd.getColumnLabel(i));
       }
       System.out.println("");
       System.out.println("------------------------------------");
       //Display data, fetching until end of the result set

       boolean more = rs.next();
       while(more){
           //Loop through each column, getting the column
           //data and displaying
           for (i=1; i<=numCols; i++){
               if(i>1)   System.out.print("                ");
               System.out.print(rs.getString(i));
           }
           System.out.print("                ");
           // Fetch the next result set row
           more = rs.next();
       }
    }
     

   class ReportHandler implements ActionListener {
       public void actionPerformed(ActionEvent event){
            String command = event.getActionCommand();
            if(command.equals("Students")){
                try{
                   showResultSet(q.doQueryR1());
                }catch(SQLException e){
                    System.out.println(e.getMessage());
                }
            }
       }
  }
}
0
Comment
Question by:CG
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7 Comments
 

Author Comment

by:CG
ID: 1225657
Edited text of question
0
 

Author Comment

by:CG
ID: 1225658
Edited text of question
0
 
LVL 8

Expert Comment

by:diakov
ID: 1225659
Here is how I do it. I have two help methods, fillString() and alignString(). You can use them to format a string to a specific length. The text area does not allow writing on a specific position (row, column), but you can generate the whole rows and append them as text. the scenarion is:
1. Set a fixed width font for the TextArea.
2. For each row of the result set, use the information from the MetaData to get its width and prepare String row for appending to the TextArea using correct calls to alignString() and fillString().

Cheers.

---------------------------
       protected void showResultSet(ResultSet r)
       {
         try
         {
           ResultSetMetaData md = r.getMetaData();
           String ctitle, cval;
           int ctype = 0, csize, ccount;
           boolean first = true;
           String displayrow = "";

           ccount = md.getColumnCount();

           while (r.next())
           {
             if (first)
             {
               first = false;
               displayrow = "";
               for (int i = 1; i <= ccount; i++)
               {
                 csize = md.getColumnDisplaySize(i);
                 ctitle = md.getColumnLabel(i);
                 displayrow += allignString(ctitle, ' ', csize);
               }
               writeln(displayrow);
               writeln(fillString('-', displayrow.length()));
             }
             displayrow = "";
             for (int i = 1; i <= ccount; i++)
             {
               ctype = md.getColumnType(i);
               csize = md.getColumnDisplaySize(i);
               if ((ctype == Types.BINARY) || (ctype == Types.LONGVARBINARY) || (ctype == Types.VARBINARY))
               {
                 cval = "BIN";
               }
               else
               {
                 if (ctype == Types.OTHER)
                 {
                   cval = "OBJ";
                 }
                 else
                 {
                   cval = r.getString(i);
                   if (r.wasNull())
       cval = "NULL";
                 }
               }
               displayrow += allignString(cval, ' ', csize);
             }
             writeln(displayrow);
           }
         }
         catch (SQLException e)
         {
           while (e != null)
           {
             writeln("[error] " + e.getMessage());
             e = e.getNextException();
             sqlerrors++;
           }
         }
       }

/this one trims a string to a size or fills it with character
       //to this size. It is usefull to make strings specifically long
       protected String allignString(String s, char c, int size)
       {
         String res = "";
         int len = s.length();
         if (len >= size)
         {
           res = s.substring(0, size);
         }
         else
         {
           String ccc = fillString(c, size - len);
           res = s + ccc;
         }
         return res;
       }
       //this one produces a string with length sizefilled with char c
       protected String fillString(char c, int size)
       {
         char data[] = new char[size];
         for (int i = 0; i < size; i++)
          data[i] = c;
         return new String(data);
       }
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Author Comment

by:CG
ID: 1225660
I don't know how to correct my program upon your suggest. Also, you did not tell
me how to call the function  showResultSet() when the user selects the subMenuItem
in the menu bar.
0
 
LVL 8

Accepted Solution

by:
diakov earned 100 total points
ID: 1225661
You have to set the font of the text area to:

t.setFont(new Font("Courier", Font.PLAIN, 12));
//then the alignment works, because each character will use the same space.
// If we assume that we know the max number of chars per line,
//you can print the title
int max_num_chars_per_line = 100;
String title = "Students"
String title_row = fillString(' ', (100 - title.length())/2) + title;

//You can print the date you wanted by
Date dt = new Date(System.currentTimeMillis());
SimpleDateFormat sdf = new SimpleDateFormat("MMM. dd, yyyy");
String date_row = sdf.format(dt);

Hope this helps,

  Nik






0
 

Author Comment

by:CG
ID: 1225662
Hi, Diakov:
Thank you for your help!  Could you please  help me to solve two more problems (40 points)?
1.  When the program gets data with type "Date/Time" using getString() from the database, it will show such as "1899-12-30 08:00:00".
So I try to add code:
  if (ctype == Types.TIME)
 {
                   cval = formatter.format(q.rs.getTime(i));
                  System.out.println(cval);
 }
but it does not work.  The system did not print out anythiing.

2. How to set the font of the title string " Font.PLAIN"
0
 

Author Comment

by:CG
ID: 1225663
SimpleDateFormat formatter = new SimpleDateFormat("hh:mm:ss a");

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