数据库查询未填充到组合框...为什么？

Question

I've been at this for awhile and have tried different examples (including a few that I found here), and tried to adapt them to what I need.

I am trying to use a DB query in a servlet to populate a combo box in the resulting html form that is created. While it all compiles and the page pops up with a combobox, there is nothing in the box to choose from, which tells me that something is wrong with how I am passing variables.

I've basically narrowed my methods down to two, but get the same results from both.
Can someone have a look-see and give me a clue?

out.print(`"<tr><td>SoldWhich Home ID:  `</td><td>"`);
//Query table for results to go into option box  
ResultSet rs1 = null;  
Statement stmt1 = null;  
Connection con1 = null;  

try {
    Class.forName(DRIVER);  
    con1 = DriverManager.getConnection(URL, username, password);  
    String sql = "SELECT home_id FROM Home";  
    stmt1 = con1.createStatement();  
    rs1 = stmt1.executeQuery(sql);  
    ArrayList<String> soldWhich = new ArrayList<String>();
    List<String> soldWhich = new ArrayList<String>();

    while (rs1.next()){
        for (int i=1;i<=rs1.getRow(); i++ ){
            String value = rs1.getString(1);
            soldWhich.add(value);
        }
    }
}
catch(Exception e){}
//Begin option box
out.print(`"<select width=\"150px\" align=\"right\" name=\"soldWhichBox\">"`);
String soldWhich[] = (String[])req.getAttribute("home_id");
//populate with query output
try{
    for(String sh : soldWhich){
        out.print(`"<option width=\"150px\" align=\"right\" value=\""+sh+"\">"+sh+"</option>"`);
    }
    rs1.close();
    con1.close();
}

catch (Exception e){}
out.print(`"</select>"`);
out.print(`"</td></tr>"`);

And the other method:

out.print(`"<tr><td>SoldWhich Home ID:  </td><td>"`);
//Query table for results to go into option box  
ResultSet rs1 = null;  
Statement stmt1 = null;  
Connection con1 = null;  
try{  

    Class.forName(DRIVER);  
    con1 = DriverManager.getConnection(URL, username, password);
    String sql = "SELECT home_id FROM Home ORDER BY home_id";
    stmt1 = con1.createStatement();
    rs1 = stmt1.executeQuery(sql);
    List<String> soldWhich = new ArrayList<String>();

    while (rs1.next()){
       soldWhich.add(rs1.getString(1));
    }
}
catch(Exception e){}
//Begin option box
out.print(`"<select width=\"150px\" align=\"right\" name=\"soldWhichBox\">"`);
String soldWhich[] = (String [])req.getAttribute("home_id");
//populate with query output
try{
    for(String sh : soldWhich){
        out.print(`"<option width=\"150px\" align=\"right\" value=\""+sh+"\">"+sh+"</option>"`);
    }
    rs1.close();
    con1.close();
}
catch (Exception e){}
out.print(`"</select>"`);
out.print(`"</td></tr>"`);

Answer 1

I think you are not actually getting values (sh) in the "for(String sh : soldWhich)" loop. Can you try printing the values in a simple table just to see if you actually get data? Also why aren't you using jstl to perform this task? And your catch block does not log any errors either in case you are actually getting some sort of errors that will go unnoticed.

Answer 2

Where are you setting "home_id" request attribute and why are you even setting it? I think you should take out the following line of code and see if it works. Modify your code to this.

List<String> soldWhich = null;
try {
    Class.forName(DRIVER);  
    con1 = DriverManager.getConnection(URL, username, password);  
    String sql = "SELECT home_id FROM Home";  
    stmt1 = con1.createStatement();  
    rs1 = stmt1.executeQuery(sql);  
    soldWhich = new ArrayList<String>();

    while (rs1.next()){
        for (int i=1;i<=rs1.getRow(); i++ ){
            String value = rs1.getString(1);
            soldWhich.add(value);
        }
    }
}