Android: RadioGroup - How to configure the event listener

Ryan picture Ryan · Jul 21, 2011 · Viewed 95.2k times · Source

From my understanding, to determine if a checkbox is "clicked" and find if it's checked or not, code such as the following can be used:

cb=(CheckBox)findViewById(R.id.chkBox1);
        cb.setOnCheckedChangeListener(this);

public void onCheckedChanged(CompoundButton buttonView, 
    boolean isChecked) { 
        if (isChecked) { 
            cb.setText("This checkbox is: checked"); 
        } 
        else { 
            cb.setText("This checkbox is: unchecked"); 
        } 
    }

However, I am unable to work out the logic on how to do the above for a radiogroup.

Here is the xml for my RadioGroup:

<RadioGroup android:id="@+id/radioGroup1" 
android:layout_width="wrap_content" 
android:layout_height="wrap_content">
    <RadioButton android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/radio1" android:checked="true" 
    android:text="RadioButton1">
    </RadioButton>
    <RadioButton android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/radio2" android:text="RadioButton2" android:checked="true">
    </RadioButton>
    <RadioButton android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/radio3" android:text="RadioButton3">
    </RadioButton>
</RadioGroup>

Question: Do i need to setup another listener, or will the listener already there also "register" this group?

Also, should the listener be set up on the RadioGroup or the RadioButton?

Answer

A. Abiri picture A. Abiri · Jul 21, 2011

This is how you get the checked radiobutton:

// This will get the radiogroup
RadioGroup rGroup = (RadioGroup)findViewById(r.id.radioGroup1);
// This will get the radiobutton in the radiogroup that is checked
RadioButton checkedRadioButton = (RadioButton)rGroup.findViewById(rGroup.getCheckedRadioButtonId());

To use the listener, you do this:

// This overrides the radiogroup onCheckListener
rGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener()
{
    public void onCheckedChanged(RadioGroup group, int checkedId)
    {
        // This will get the radiobutton that has changed in its check state
        RadioButton checkedRadioButton = (RadioButton)group.findViewById(checkedId);
        // This puts the value (true/false) into the variable
        boolean isChecked = checkedRadioButton.isChecked();
        // If the radiobutton that has changed in check state is now checked...
        if (isChecked)
        {
            // Changes the textview's text to "Checked: example radiobutton text"
            tv.setText("Checked:" + checkedRadioButton.getText());
        }
    }
});