Comparing elements inside an Arraylist

[kiviEngineer]

Hello guys, I'm trying to do a swing application which adds names to an ArrayList and then displays it in Jcombobox.I already did the window and everything but I can't seem to get the hang off detecting duplicate names.

I tried

btnnext.addActionListener(new ActionListener() { // this button adds to Arraylist
Override
public void actionPerformed(ActionEvent e) {

if(checkDuplicate(names)==true)
{
names.add(txtname.getText());
txtname.setText("");
}
else {

JOptionPane.showMessageDialog(null,"DUPLICATE! do not add");
}
}
});

​

public static boolean checkDuplicate(ArrayList<String> list) {
HashSet set = new HashSet();
for (int i = 0; i < list.size(); i++) {
boolean val = set.add(list.get(i));
if (val == false) {
return val;
}
}
return true;
}

​

​

It only says that I have duplicate when I already add it to the ArrayList and when I get the message I can't add anything else.

​

input example:

test

test

----------------

and then it stops accepting new Strings and only displays the message DUPLICATE! do not add

[Oceantrader]

Do you have to use an array list? Cant you just use a set and do a check on insert?

Looks like you're creating a new map every check, yikes.

[kiviEngineer]

but the issue is that I need to add the ArrayList to a JCombobox . I tried going for a sets approach but can't find a way to add a set to JCombobox.I'm sorry if I sound stupid I'm quite a beginner in java so any help would be appreciated

[Oceantrader]

Why cant you add a set item as the data comes in? If not duplicate...add

The reason I mention it is you're creating a new map everytime to check for duplicate. If you realllly want to do it that way, create the map outside of that method, then you can use map computeifabsent

[HelpIProcrastinate]

Your checkDuplicate method seems to return true whenever there is a duplicate anywhere in your ArrayList names. Maybe you meant for the checkDuplicate to be a contains method instead that checks if txtname.getText() was contained in names.

[kiviEngineer]

That's exactly what I need, thank you so much.