exception when trying to add class in a hashset

**asa** · 05-19-2012, 10:15 PM

Hello,

I am trying to extract some values from a DB table and save it in a hashset.

Here is my code,

Java Code:

public HashSet selectAll() {

		HashSet users=new HashSet ();
		ResultSet rs=null;
		boolean b = false;
		try {
		Statement st = con.createStatement();
		rs = st.executeQuery("select id,name,age,job from company.user;");
		
		while(rs.next())
		{
			b= users.add(new UserModel(rs.getInt("id"), rs.getInt("age"), rs.getString("name"), rs.getString("job")));	
			System.out.println(b);
		}
				
		}
		catch (SQLException ex) {
		ex.printStackTrace();
		}
		
		return users;
	}

when I try executing the code, I get this exception and don't understand it.

true
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: Assignment1.UserModel cannot be cast to java.lang.String
at Assignment1.Displayer.<init>(Displayer.java:29)
at Assignment1.MainFrame$4.actionPerformed(MainFrame. java:66)
at javax.swing.AbstractButton.fireActionPerformed(Abs tractButton.java:2028)
at javax.swing.AbstractButton$Handler.actionPerformed (AbstractButton.java:2351)
at javax.swing.DefaultButtonModel.fireActionPerformed (DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultB uttonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseRe leased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.jav a:6373)
at javax.swing.JComponent.processMouseEvent(JComponen t.java:3267)
at java.awt.Component.processEvent(Component.java:613 8)
at java.awt.Container.processEvent(Container.java:208 5)
at java.awt.Component.dispatchEventImpl(Component.jav a:4735)
true
true
true
true
true
true
true
at java.awt.Container.dispatchEventImpl(Container.jav a:2143)
at java.awt.Component.dispatchEvent(Component.java:45 65)
at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:4621)
at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:4282)
at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:4212)
at java.awt.Container.dispatchEventImpl(Container.jav a:2129)
at java.awt.Window.dispatchEventImpl(Window.java:2478 )
at java.awt.Component.dispatchEvent(Component.java:45 65)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.j ava:679)
at java.awt.EventQueue.access$000(EventQueue.java:85)
at java.awt.EventQueue$1.run(EventQueue.java:638)
at java.awt.EventQueue$1.run(EventQueue.java:636)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:652)
at java.awt.EventQueue$2.run(EventQueue.java:650)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 649)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:296)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:196)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:188)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:122)

Thanks.

**Fubarable** · 05-19-2012, 10:50 PM

Which line causes this exception?

Edit: code tags added to your question.

**asa** · 05-19-2012, 11:00 PM

It looks this line

Java Code:

b= users.add(new UserModel(rs.getInt("id"), rs.getInt("age"), rs.getString("name"), rs.getString("job")));

even I see true printed for the first iteration!

**Fubarable** · 05-19-2012, 11:22 PM

And you're sure that you're not using a generic HashSet<String> anywhere?

**asa** · 05-19-2012, 11:41 PM

Yes, I call it from here.

Java Code:

HashSet rs = DB.selectAll();
		Iterator iterator = rs.iterator();
		
		JComboBox names = new JComboBox();
		while (iterator.hasNext()) {
			names.addItem(iterator.next());
		}
		this.add(names);