An important part of the job as a front-end developer is to stay up to date and in contact with new tools, trends and workflows. That’s why you cannot miss this upcoming webinar to explore the latest trends in UI technologies!
Solved
adding new items into JComboBox
Posted on 2004-04-29
Hi,
I have a JComboBox already. And now I would like make this JComboBox bigger, more choices, if some flags are set. How can I do this?
Here is my codes...
String ComboBoxStr[] = { "a1", "a2", "a3", "a4", "a5"};
JComboBox aComboBox = new JComboBox(ComboBoxStr);
Boolean setFlag = false;
if (setFlag == true)
{
// let say if I want to have 5 more choices like this...ComboBoxStr[] = { "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10"};
// so what can I do here???
}
I have a JComboBox already. And now I would like make this JComboBox bigger, more choices, if some flags are set. How can I do this?
Here is my codes...
String ComboBoxStr[] = { "a1", "a2", "a3", "a4", "a5"};
JComboBox aComboBox = new JComboBox(ComboBoxStr);
Boolean setFlag = false;
if (setFlag == true)
{
// let say if I want to have 5 more choices like this...ComboBoxStr[] = { "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10"};
// so what can I do here???
}
[X]
Welcome to Experts Exchange
Add your voice to the tech community where 5M+ people just like you are talking about what matters.
- Help others & share knowledge
- Earn cash & points
- Learn & ask questions
5-
4
3
12 Comments
you can just add the new items. eg.
aComboBox.addItem("a6");
aComboBox.addItem("a7");
aComboBox.addItem("a8");
aComboBox.addItem("a9");
aComboBox.addItem("a10");
aComboBox.addItem("a6");
aComboBox.addItem("a7");
aComboBox.addItem("a8");
aComboBox.addItem("a9");
aComboBox.addItem("a10");
If I do have an ActionListener when I first initialized aComboBox and now I add some new items...will the new items also ahve action listener???
so that means I don't need to add ActionListener to the new items?? Ok...so if I want to remove the new item...I need to use "removeItem"??
How can I know whether the new item I wanna add is existing in a JComboBox so I won't add another one again??
How can I know whether the new item I wanna add is existing in a JComboBox so I won't add another one again??
>> so that means I don't need to add ActionListener to the new items??
The actionlistener listens to actions happening on *the combobox* no matter how many items are in it
>> if I want to remove the new item
To remove you can use
void removeItem(Object anObject)
or
void removeItemAt(int anIndex)
For the first you have to pass the object that is in it
For the first you only need to pass the index
>>How can I know whether the new item I wanna add is existing in a JComboBox so I won't add another one again??
Whenever you add an item to it or remove an item from it, you could also add/remove it from a Set.
Then before adding you could look if it exists in the set. If so, you shouldn't add it anymore.
(The Set is for not having to interrogate each item of the Combobox to check if the item you want to insert is already in)
The actionlistener listens to actions happening on *the combobox* no matter how many items are in it
>> if I want to remove the new item
To remove you can use
void removeItem(Object anObject)
or
void removeItemAt(int anIndex)
For the first you have to pass the object that is in it
For the first you only need to pass the index
>>How can I know whether the new item I wanna add is existing in a JComboBox so I won't add another one again??
Whenever you add an item to it or remove an item from it, you could also add/remove it from a Set.
Then before adding you could look if it exists in the set. If so, you shouldn't add it anymore.
(The Set is for not having to interrogate each item of the Combobox to check if the item you want to insert is already in)
Avoiding duplicates:
Set theSet = new HashSet()
1) Adding to the combo box should be like this:
instead of
yourCombo.add("a1");
you should write:
if ( !theSet.contains("a1") ) {
yourCombo.add("a1");
theSet.add("a1")
}
2) Removing
instead of
yourCombo.removeItem("a1")
you should write:
yourCombo.removeItem("a1")
theSet.remove("a1");
Set theSet = new HashSet()
1) Adding to the combo box should be like this:
instead of
yourCombo.add("a1");
you should write:
if ( !theSet.contains("a1") ) {
yourCombo.add("a1");
theSet.add("a1")
}
2) Removing
instead of
yourCombo.removeItem("a1")
you should write:
yourCombo.removeItem("a1")
theSet.remove("a1");
Featured Post
![[Webinar] Lessons on Recovering from Petya](https://filedb.experts-exchange.com/files/public/2017/7/11/dcb3272a-62a8-4274-a34e-d1771610ec3b.png)
Skyport is working hard to help customers recover from recent attacks, like the Petya worm. This work has brought to light some important lessons. New malware attacks like this can take down your entire environment. Learn from others mistakes on how to prevent Petya like worms.
Question has a verified solution.
If you are experiencing a similar issue, please ask a related question
An old method to applying the Singleton pattern in your Java code is to check if a static instance, defined in the same class that needs to be instantiated once and only once, is null and then create a new instance; otherwise, the pre-existing insta…
Java functions are among the best things for programmers to work with as Java sites can be very easy to read and prepare. Java especially simplifies many processes in the coding industry as it helps integrate many forms of technology and different d…
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it.
Define Error Message:
Line Numbers:
Type of Error:
Break Down…
This tutorial covers a step-by-step guide to install VisualVM launcher in eclipse.
Suggested Courses
Course of the Month4 days, 9 hours left to enroll
661 members asked questions and received personalized solutions in the past 7 days.
Join the community of 500,000 technology professionals and ask your questions.