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Prevent form submission if radio button isn't checked

Working on an education android app. One provides answers through EditText input, radio buttons and CheckBox.
I want a check for the RadioGroup that when no RadioButton is clicked it will prompt the student and prevent submission. I succeeded in EditText but unsucessful for RadioButton.
public void checkEmptyButtons(View view){
RadioGroup rg = (RadioGroup) findViewById(R.id.myRg);
if (rg.getCheckedRadioButton()==-1{
// this is where I have a problem
//I don't even know how to search on the //dev.anderoid site
}
}
That's where am stucked. Thanks in advance
.

you need radioGroup checked Change Listener:
rg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
//here you will get callback everytime radio button is checked along with id. You can have boolean checked here to know if any of your radio button is checked
}
});

Use getCheckedRadioButtonId() in stead of getCheckedRadioButton().
if (rg.getCheckedRadioButtonId() == -1) {
//no radio buttons are checked
}
else {
//any one of the radio buttons is checked
}

RadioButton Issue get checked when sending?

Having two RadioButtons and button send.
When I click on the send button the 2 RadioButtons are checked.
How to avoid this?
enter image description here

You need to group the radio buttons so inside the xml add the radio buttons inside this tag:
<RadioGroup> .....</RadioGroup>
then in your activity do this:
RadioGroup radioGroup = (RadioGroup) findViewById(R.id.myRadioGroup); //declare the radiogroup
radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// find which radio button is selected
if(checkedId == R.id.radiobtn1) {
//code here
} else if(checkedId == R.id.radiobtn2) {
//code here
} else {
//code here
}
}
});

If you want only one RadioButton to be checked at once, keep them inside a RadioGroup.

Just Put your RadioButtons inside RadioGroup

Android -get radio button id based on value

I want to highlight right and wrong option when user clicks a button after checking an radio button. If that option is right, highlight. Else highlight right option.
Is there any way to get radio button id in a group based on its value? Or Do I need to use switch case?
I searched enough but not able to find out what I need.
Edit
I have simple layout which contains one question, 4 choices, one button. User check a radio button and click the check button. If user selects wrong option, highlight the correct option. I know what is correct option by value.
choice1, choice2, choice3, choice4 are four radio buttons. User checks choice3. But choice2 is correct. How do I select choice2 by value in this radio group.
group.getRadioButtonId("choice2")
Anything similar to this?

You could iterate through the children of your RadioGroup to get the required one:
int count = radioGroup.getChildCount();
for (int i = 0 ; i < count; i++) {
RadioButton button = (RadioButton) radioGroup.getChildAt(i);
if (button.getText().equals("choice2")) {
int id = button.getId(); // the ID you're looking for
}
}

You Can check like this
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// TODO Auto-generated method stub
int rbId = group.getCheckedRadioButtonId();
RadioButton rb = (RadioButton) findViewById(rbId);
switch (group.getId()) {
case R.id.radiogroupID:
if (rb.getText().toString().equalsIgnoreCase("right")) {
// your logic
} else {
//your logic
}
}
}

you can use these line. its working for me
int checkedId = radioGroup.getCheckedRadioButtonId();
View radioButton = radioGroup.findViewById(checkedId);
int radioId = radioGroup.indexOfChild(radioButton);
RadioButton btn = (RadioButton) radioGroup.getChildAt(radioId);

First check which option is true. hear choice 2 OK. set by default is checked true and than check user checked value . if user select other option than display message and pass true option we already checked true

Create an int array with all the ids of the radiobutton
int[] rb_IDs=new int[]{R.id.rb1,R.id.rb2,R.id.rb3};
Then inside your button click :
RadioGroup rg=(RadioGroup) findViewById(R.id.rg);
rg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
for (int i=0;i<rb_IDs.length;i++)
{
RadioButton rb=(RadioButton)findViewById(rb_IDs[i]);
if (rb.getText().toString().equals("YOUR CORRECT ANSWER")&&!rb.isChecked())
{
//
//Do your thing
//
//ID of the correct answer Radiobutton is
int id=rb_IDs[i];
//HighLighting the answer
rb.setBackgroundColor(Color.parseColor("#00ff00"));
break;
}
}
}
});

multiple radio groups with only one allowed selection?

For layout purposes I have three radiogroups with multiple selections in each group. How can I code so that only one choice is allowed, across all three groups?
In other words, right now I can make a selection in each group for a total of 3 selections. I want these to "see" each other and only allow one selection total.

Here's the method:
private RadioButton lastCheckedRB = null;
//whatever code
//onClicklistener for radiogroup does not work
RadioGroup.OnCheckedChangeListener listener = new RadioGroup.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
RadioButton checked_rb = (RadioButton) group.findViewById(checkedId);
//OnCheckedChangeListener checks for reclick of a clicked rb, so the rest of the code is not executed
if (lastCheckedRB != null) {
lastCheckedRB.setChecked(false);
}
//store the clicked radiobutton
lastCheckedRB = checked_rb;
}
};
radioGroup1.setOnCheckedChangeListener(listener);
radioGroup2.setOnCheckedChangeListener(listener);

How to set OnClickListener on a RadioButton in Android?

I have two RadioButtons inside a RadioGroup. I want to set OnClickListener on those RadioButtons. Depending on which RadioButton is clicked, I want to change the text of an EditText. How can I achieve this?

I'd think a better way is to use RadioGroup and set the listener on this to change and update the View accordingly (saves you having 2 or 3 or 4 etc listeners).
RadioGroup radioGroup = (RadioGroup) findViewById(R.id.yourRadioGroup);
radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener()
{
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// checkedId is the RadioButton selected
}
});

Hope this will help you...
RadioButton rb = (RadioButton) findViewById(R.id.yourFirstRadioButton);
rb.setOnClickListener(first_radio_listener);
and
OnClickListener first_radio_listener = new OnClickListener (){
public void onClick(View v) {
//Your Implementaions...
}
};

radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener()
{
public void onCheckedChanged(RadioGroup group, int checkedId) {
// checkedId is the RadioButton selected
RadioButton rb=(RadioButton)findViewById(checkedId);
textViewChoice.setText("You Selected " + rb.getText());
//Toast.makeText(getApplicationContext(), rb.getText(), Toast.LENGTH_SHORT).show();
}
});

The question was about Detecting which radio button is clicked, this is how you can get which button is clicked
final RadioGroup radio = (RadioGroup) dialog.findViewById(R.id.radioGroup1);
radio.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
View radioButton = radio.findViewById(checkedId);
int index = radio.indexOfChild(radioButton);
// Add logic here
switch (index) {
case 0: // first button
Toast.makeText(getApplicationContext(), "Selected button number " + index, 500).show();
break;
case 1: // secondbutton
Toast.makeText(getApplicationContext(), "Selected button number " + index, 500).show();
break;
}
}
});

For Kotlin Here is added the lambda expression and Optimized the Code.
radioGroup.setOnCheckedChangeListener { radioGroup, optionId ->
run {
when (optionId) {
R.id.radioButton1 -> {
// do something when radio button 1 is selected
}
R.id.radioButton2 -> {
// do something when radio button 2 is selected
}
// add more cases here to handle other buttons in the your RadioGroup
}
}
}
Hope this will help you. Thanks!

You could also add listener from XML layout: android:onClick="onRadioButtonClicked" in your <RadioButton/> tag.
<RadioButton android:id="#+id/radio_pirates"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/pirates"
android:onClick="onRadioButtonClicked"/>
See Android developer SDK- Radio Buttons for details.

Since this question isn't specific to Java, I would like to add how you can do it in Kotlin:
radio_group_id.setOnCheckedChangeListener({ radioGroup, optionId -> {
when (optionId) {
R.id.radio_button_1 -> {
// do something when radio button 1 is selected
}
// add more cases here to handle other buttons in the RadioGroup
}
}
})
Here radio_group_id is the assigned android:id of the concerned RadioGroup. To use it this way you would need to import kotlinx.android.synthetic.main.your_layout_name.* in your activity's Kotlin file. Also note that in case the radioGroup lambda parameter is unused, it can be replaced with _ (an underscore) since Kotlin 1.1.

Just in case someone else was struggeling with the accepted answer:
There are different OnCheckedChangeListener-Interfaces. I added to first one to see if a CheckBox was changed.
import android.widget.CompoundButton.OnCheckedChangeListener;
vs
import android.widget.RadioGroup.OnCheckedChangeListener;
When adding the snippet from Ricky I had errors:
The method setOnCheckedChangeListener(RadioGroup.OnCheckedChangeListener) in the type RadioGroup is not applicable for the arguments (new CompoundButton.OnCheckedChangeListener(){})
Can be fixed with answer from Ali :
new RadioGroup.OnCheckedChangeListener()

RadioGroup radioGroup = (RadioGroup) findViewById(R.id.yourRadioGroup);
radioGroup.setOnClickListener(v -> {
// get selected radio button from radioGroup
int selectedId = radioGroup.getCheckedRadioButtonId();
// find the radiobutton by returned id
radioButton = findViewById(selectedId);
String slectedValue=radioButton.getText()
});