ListView - can't get OnCheckedChangeListener (Checkboxes) to work

Question

5.00/5 (1 vote)

See more:

EDIT: Based on evolution of the problem, I edited this question.

So the problem is: I want to populate a ListView with checkboxes, and as I want to customize my ListView I'm not using simple_multiple_choice_mode, I'm putting my layout on list_item.xml: (for each row)

        <checkbox>
xmlns:android="http://schemas.android.com/apk/res/android" android:paddingLeft="8mm"
android:layout_width="fill_parent"
        android:layout_height="wrap_removed" android:id="@+id/nomeAPP" style="?listItem">
        </checkbox>

My ListView is on lista.xml

XML

<ListView android:id="@android:id/list"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        style="?whiteBackground">

</ListView>

my adapter:

XML

list=getListView();
            this.setListAdapter(new ArrayAdapter<String>(this,
                    R.layout.list_item, aux));

So I'm trying to make a setOnCheckedChangeListener for the checkboxes, so I can store the chosed items in an array.

So I did this listener based on the answer below:

C#

CheckBox cb = (CheckBox) findViewById(R.id.CheckBox01);
            cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {

                public void onCheckedChanged(CompoundButton buttonView,
                        boolean isChecked) {
                    // TODO Auto-generated method stub
                    if (buttonView.isChecked()) {
                        Toast.makeText(getBaseContext(), "Checked",
                                Toast.LENGTH_SHORT).show();
                    }
                    else
                    {
                        Toast.makeText(getBaseContext(), "UnChecked",
                                Toast.LENGTH_SHORT).show();
                    }

                }
            });

Problem is: I get the NULL exception. The CURIOUS thing is: if I "switch" my layout for a simple

XML

<ScrollView android:id="@+id/widget54" android:layout_width="fill_parent"
android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android">

<LinearLayout android:orientation="vertical"
android:layout_width="fill_parent" android:layout_height="fill_parent">
<CheckBox android:text="Checkbox" android:id="@+id/CheckBox01"
android:layout_width="wrap_content" android:layout_height="wrap_content"></CheckBox>
</LinearLayout>

</ScrollView>

And forget my ListView, it works! So, what's wrong with my layout?

I created a new little project just to let you guys see exactly the situation. It's available here[^] Right now does not work, but if you uncomment the adapter, change ListActivity to Activity and change setContentView, it will work (checked/unchecked toast text).

Another curious thing I found is that with ListActivity does not work never.... wondering if it's related...

Posted 13-Sep-11 2:54am

Maxdd 7

Updated 14-Sep-11 3:51am

v6

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

TorstenH. · Answer 1 · 2011-09-13T05:32:00

I answered last time: http://www.codeproject.com/Questions/253369/Problem-getting-Checkbox-items-on-the-ListView

and it is still a common problem.

Read the answers of that stackoverflow-thread and you'll find this:

Java

private void addClickHandlerToCheckBox(CheckBox checkbox) {
    checkbox.setOnCheckedChangeListener(new OnCheckedChangeListener() {
        public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
            CheckBox checkbox = (CheckBox)arg0; 
            boolean isChecked = checkbox.isChecked();
            // Store the boolean value somewhere durable
        }
    }
);

then you can access the value that you have stored "somewhere durable".

EDIT:

You need to add the listener to the checkbox - otherwise you will not know which checkbox has been hit.

Java

   // HashMap as member variable to store state of the checkboxes
   // needs to be final to be accessed in anonymous listener class
   // Don't be scared by the Key and Value, those work as fine as int and boolean
   private final HashMap<integer,> oMapCheckBoxSelection = new HashMap<integer,>;

   // ID's for the Checkboxes
   // store as variable to have a common reference
   private final static int
     iCheckBoxXY = 0,
     iCheckBoxXZ = 1;
{
   
   // ...

   CheckBox oCheckBoxXY = (CheckBox) findViewById(R.id.nomeAPP);
   oCheckBoxXY.setID();
   addClickHandlerToCheckBox(oCheckboxXY);


   // ....

   // Check if the checkbox is in the Hashmap and read it.
   if(oMapCheckBoxSelection.contains(iCheckBoxXY)){
     boolean isCheckboxSelected = oMapCheckBoxSelection.get(iCheckBoxXY);
   }


}

private void addClickHandlerToCheckBox(CheckBox checkbox) {
    checkbox.setOnCheckedChangeListener(new OnCheckedChangeListener() {
        public void onCheckedChanged(CompoundButton arg0, boolean arg1) {
            CheckBox checkbox = (CheckBox)arg0; 
            oMapCheckBoxSelection.put(checkbox.getID(), checkbox.isChecked());
        }
    }
);

Problem is to get a proper initialized HashMap Value and to verify if it is initialized before you try to read that value.
You might also init the HashMap-Value when you init the Checkbox:
oMapCheckBoxSelection.put(oCheckBoxXY.getID(), oCheckBoxXY.isChecked());
...but I'd like to prefer the check with HashMap.contains to make sure it is.