Access Database and Selecting items

asked 2009-11-27 10:06:40 +0800

JoH
105 ● 2 ● 3

Dear all,

I'm new to java prgramming.

I created a database named lmudb with two accounts.
One for the administrator, who has the ability to modify the database.
And the other one is only for the guest, who has the ability to search the database.

The .zul file below is the window for the guest.
My Problem is, I could display the content of the database instantly by implementing the method I created in another class, and also select the the filedir by the method select(), and show the file directory in the message box by clicking the button test (shown in the <west></west> area).

But then, if the user search or filter a string, let's say "cysteine", the new list will be showed. And if one try to click the button test again using the method select(), it doesn't work. It seems the new list cannot be found by the method select().
The error message I got:
Attempt to invoke method getFiledir on null value

How could I make that the method select still invokable while a new list is being created?

Thanks for every reply,

-Johnny-

<?page id="UserZul" title=" New ZUL Title" cacheable="false"
language="xul/html" zscriptLanguage="Java" contentType="text/html;charset=UTF-8"?>
<?init class="org.zkoss.zkplus.databind.AnnotateDataBinderInit"?>

<zk xmlns="http://www.zkoss.org/2005/zul"
xmlns:h="http://www.w3.org/1999/xhtml"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.zkoss.org/2005/zul http://www.zkoss.org/2005/zul/zul.xsd">

<window id="guestWnd" title="Database Search" border="normal" width="1422px" use="lmu.qc.ui.PeopleWindow">
<zscript >
public void select(){ Listitem li = items.getSelectedItem();
if(li!=null){ String filedir =
((lmu.qc.domain.Item)li.getValue()).getFiledir();
Messagebox.show("Are you sure of show " + filedir); } }
</zscript>

<zscript language="Java">{
import java.sql.*;

public void submit1() {

Connection conn = null;
try
{
String userName = "root";
String password = "compound";
String url = "jdbc:mysql://localhost:3306/lmudb";
Class.forName ("com.mysql.jdbc.Driver").newInstance ();
conn = DriverManager.getConnection (url, userName, password);
System.out.println ("Database connection established");

Statement s = conn.createStatement ();
s.executeQuery ("SELECT * FROM items WHERE strform like '%"+ strform.value+"%'");
ResultSet rs = s.getResultSet ();

while (items.getItemCount() > 0) {
items.removeItemAt(0);
}
while (rs.next())
{
Listitem li = new Listitem();

li.appendChild(new Listcell(rs.getString("strform")));
li.appendChild(new Listcell(rs.getString("filedir")));
li.appendChild(new Listcell(rs.getString("description")));
li.appendChild(new Listcell(rs.getString("qcmeth")));
li.appendChild(new Listcell(rs.getString("pg")));
li.appendChild(new Listcell(rs.getString("es")));
li.appendChild(new Listcell(rs.getString("multi")));
li.appendChild(new Listcell(rs.getString("charge")));
li.appendChild(new Listcell(rs.getString("energy")));
items.appendChild(li);
}
rs.close ();
s.close ();
}
catch (Exception e)
{
System.err.println ("ERROR: "+ e.getMessage());
}
finally
{
if (conn != null)
{
try
{
conn.close ();
System.out.println ("Database connection terminated");
}
catch (Exception e) { /* ignore close errors */ }
}
}

}



public void submit2() {

Connection conn = null;
try
{
String userName = "root";
String password = "compound";
String url = "jdbc:mysql://localhost:3306/lmudb";
Class.forName ("com.mysql.jdbc.Driver").newInstance ();
conn = DriverManager.getConnection (url, userName, password);
System.out.println ("Database connection established");

Statement s = conn.createStatement ();
s.executeQuery ("SELECT * FROM items WHERE description like '%"+ description.value+"%'");
ResultSet rs = s.getResultSet ();

while (items.getItemCount() > 0) {
items.removeItemAt(0);
}
while (rs.next())
{
Listitem li = new Listitem();

li.appendChild(new Listcell(rs.getString("filedir")));
li.appendChild(new Listcell(rs.getString("strform")));
li.appendChild(new Listcell(rs.getString("description")));
li.appendChild(new Listcell(rs.getString("qcmeth")));
li.appendChild(new Listcell(rs.getString("pg")));
li.appendChild(new Listcell(rs.getString("es")));
li.appendChild(new Listcell(rs.getString("multi")));
li.appendChild(new Listcell(rs.getString("charge")));
li.appendChild(new Listcell(rs.getString("energy")));
items.appendChild(li);
}

rs.close ();
s.close ();
}
catch (Exception e)
{
System.err.println ("ERROR: "+ e.getMessage());
}
finally
{
if (conn != null)
{
try
{
conn.close ();
System.out.println ("Database connection terminated");
}
catch (Exception e) { /* ignore close errors */ }
}
}

}





}</zscript>

<grid>
<rows>
<row>Structure Formula: <textbox width="99%" id="strform" /><button id="search1" label="Search by Structure Formula" onClick="submit1()"/></row>
<row>Description: <textbox id="description" width="99%" /><button id="search2" label="Search by Description" onClick="submit2()"/></row>
</rows>
</grid>
<borderlayout height="1000px"><west title="Result List" width="1012px" splittable="true" border="none" flex="true" collapsible="true">
<listbox id="items" width="1012px" mold="paging" onCreate="guestWnd.showList()">
<listhead>
<listheader width="100px" label="File Path" />
<listheader sort="auto" width="120px" label="Structure Formula" />
<listheader sort="auto" width="100px" label="Description" />
<listheader width="120px" label="Methods" />
<listheader width="50px" label="PG" />
<listheader width="50px" label="ES" />
<listheader width="80px" label="Multiplicity" />
<listheader width="100px" label="Charge" />
<listheader sort="auto" width="120px" label="Energy" />
</listhead>
</listbox>
</west>
<east title="Jmol Display" width="390px" collapsible="true" flex="true">
<button label="test" onClick="select()" />
</east>
</borderlayout>
</window>
</zk>