Write something to text field when any item from combobox is selected

Question

I want to write something to a text field when I select any item from combo box. But I couldn't do this.

Java code:

comboBox.addItemListener(new ItemListener() {
    public void itemStateChanged(ItemEvent arg0) {
            if(comboBox.getSelectedItem()=="apple") {
                tfbf.setText("apple selected");
            }
        }
    });

Well you compare objects equality with `equals`.. `==` just compares reference if they pointing to the same object — nachokk, Jan 13 '14 at 18:48

score 5 · Accepted Answer · edited May 23 '17 at 12:29

5

As you don't provide any valid example . You compare object observational equality with equals(..) not with ==.

"apple".equals(comboBox.getSelectedItem())

Read more How do I compare strings in Java?

== tests for reference equality.

.equals() tests for value equality.

edited May 23 '17 at 12:29

Community

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answered Jan 13 '14 at 18:50

nachokk

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thanks so much. I ve solved with this code – user3191435 Jan 13 '14 at 19:34
Nitpick "apple".equals(comboBox.getSelectedItem()) would avoid possible NullPointerException ... +1 – MadProgrammer Jan 13 '14 at 20:14
@MadProgrammer i appreciate yoda style but for this example i think is not necessary, by the way it's not 5 am there? – nachokk Jan 13 '14 at 20:16
@nachokk Good practice makes perfect and yes... – MadProgrammer Jan 13 '14 at 21:42
@MadProgrammer ok i edited – nachokk Jan 17 '14 at 16:56

score 3 · Answer 2 · answered Jan 13 '14 at 18:54

3

comboBox.addItemListener(new ItemListener() {
    public void itemStateChanged(ItemEvent arg0)
    {
        if(comboBox.getSelectedItem()=="apple")
        {
              tfbf.setText("apple selected");
        }
    }
});

Is probably better written as:

comboBox.addItemListener(new ItemListener() {
    public void itemStateChanged(ItemEvent arg0)
    {
        tfbf.setText(comboBox.getSelectedItem() + " selected");
    }
});

answered Jan 13 '14 at 18:54

Andrew Thompson

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@assylias I do not understand your comment. Are you referring to me or the OP? I added the Swing tag of course. I intimated Swing from the use of `ItemListener`. Does Java-FX also use the `ItemListener`? – Andrew Thompson Jan 13 '14 at 19:04
for some reason I thought it was a JavaFX ComboBox but I was mistaken! In JavaFX it would be something like: `comboBox.addChangeListener(...)` – assylias Jan 13 '14 at 19:07
@assylias Aah.. I must admit I am not entirely sure it is Swing. It could be pure AWT for all I know. OP - For better help sooner, post an **[MCVE](http://stackoverflow.com/help/mcve).** – Andrew Thompson Jan 13 '14 at 19:09
Nice! Did you write that? It looks like MVCE == summarize(SSCCE)! – assylias Jan 13 '14 at 19:15
1

@assylias Thanks! It is based on [what I wrote](http://meta.stackexchange.com/a/215383/155831) (community WIKI answer). – Andrew Thompson Jan 13 '14 at 19:17
@assylias I actually just noticed it has become MCVT on that thread! ;) – Andrew Thompson Jan 13 '14 at 19:20
1

so now it will be `For better help sooner post a MCVT` ? – nachokk Jan 13 '14 at 19:42
1

@nachokk No.. for the moment I'm sticking with what it is seen at http://stackoverflow.com/help/mcve (I suspect the Wiki change will not be adopted). – Andrew Thompson Jan 13 '14 at 19:48

Write something to text field when any item from combobox is selected

2 Answers2