How to group a 3x3 grid of radio buttons?

Question

As the title describes, I'm trying to group up a grid of 3x3 radio buttons into a single radio group. In a previous question asked I learned that for radio buttons to correspond to a single group they had to be the immediate children of the radio group to which they will correspond. I learned this the hard way when I attempted to encapsulate an entire table layout (with the radio buttons in the table rows) in a radio group.

Running into that wall, I tried the following:

<TableLayout android:id="@+id/table_radButtons" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"
        android:layout_below="@+id/title_radGroup_buffer">

        <TableRow>
            <RadioGroup android:layout_width="fill_parent" 
                android:layout_height="wrap_content" 
                android:orientation="horizontal"
                android:id="@+id/radGroup1">  

                <RadioButton android:id="@+id/rad1" 
                    android:text="Button1" 
                    android:layout_width="105px" 
                    android:layout_height="wrap_content" 
                    android:textSize="13px"></RadioButton>
                <RadioButton android:id="@+id/rad2" 
                    android:text="Button2" 
                    android:layout_width="105px" 
                    android:textSize="13px" 
                    android:layout_height="wrap_content"></RadioButton>
                <RadioButton android:id="@+id/rad3" 
                    android:text="Button3" 
                    android:layout_width="105px" 
                    android:textSize="13px" 
                    android:layout_height="wrap_content"></RadioButton>
            </RadioGroup>
        </TableRow>
        <TableRow>
            <RadioGroup android:layout_width="fill_parent" 
                android:layout_height="wrap_content" 
                android:orientation="horizontal"
                android:id="@+id/radGroup1">
                  <!-- snippet -->
        </TableRow>
        <!-- snippet --->
</TableLayout>

Obviously I didn't learn the first time because I ran into a wall again. I was hoping that the radio buttons in different table rows would notice that they were part of the same radio group (gave each group the same ID) but this didn't work.

Is there any way I can group all of these buttons into a single radio group and still maintain my 3x3 structure (3 rows, 3 radio buttons in each row)?

Answer 1

Actually it's not that hard if you subclass TableLayout like in this example

/**
 * 
 */
package com.codtech.android.view;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.RadioButton;
import android.widget.TableLayout;
import android.widget.TableRow;

/**
 * @author diego
 *
 */
public class ToggleButtonGroupTableLayout extends TableLayout  implements OnClickListener {

    private static final String TAG = "ToggleButtonGroupTableLayout";
    private RadioButton activeRadioButton;

    /** 
     * @param context
     */
    public ToggleButtonGroupTableLayout(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    /**
     * @param context
     * @param attrs
     */
    public ToggleButtonGroupTableLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onClick(View v) {
        final RadioButton rb = (RadioButton) v;
        if ( activeRadioButton != null ) {
            activeRadioButton.setChecked(false);
        }
        rb.setChecked(true);
        activeRadioButton = rb;
    }

    /* (non-Javadoc)
     * @see android.widget.TableLayout#addView(android.view.View, int, android.view.ViewGroup.LayoutParams)
     */
    @Override
    public void addView(View child, int index,
            android.view.ViewGroup.LayoutParams params) {
        super.addView(child, index, params);
        setChildrenOnClickListener((TableRow)child);
    }


    /* (non-Javadoc)
     * @see android.widget.TableLayout#addView(android.view.View, android.view.ViewGroup.LayoutParams)
     */
    @Override
    public void addView(View child, android.view.ViewGroup.LayoutParams params) {
        super.addView(child, params);
        setChildrenOnClickListener((TableRow)child);
    }


    private void setChildrenOnClickListener(TableRow tr) {
        final int c = tr.getChildCount();
        for (int i=0; i < c; i++) {
            final View v = tr.getChildAt(i);
            if ( v instanceof RadioButton ) {
                v.setOnClickListener(this);
            }
        }
    }

    public int getCheckedRadioButtonId() {
        if ( activeRadioButton != null ) {
            return activeRadioButton.getId();
        }

        return -1;
    }
}

and create a layout like this (of course you need to clean it up but you got the idea)

<?xml version="1.0" encoding="utf-8"?>
<com.codtech.android.view.ToggleButtonGroupTableLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:id="@+id/radGroup1">
    <TableRow>
            <RadioButton android:id="@+id/rad1" android:text="Button1"
                android:layout_width="105px" android:layout_height="wrap_content"
                android:textSize="13px" />
            <RadioButton android:id="@+id/rad2" android:text="Button2"
                android:layout_width="105px" android:textSize="13px"
                android:layout_height="wrap_content" />
            <RadioButton android:id="@+id/rad3" android:text="Button3"
                android:layout_width="105px" android:textSize="13px"
                android:layout_height="wrap_content" />
    </TableRow>
    <TableRow>
            <RadioButton android:id="@+id/rad1" android:text="Button1"
                android:layout_width="105px" android:layout_height="wrap_content"
                android:textSize="13px" />
            <RadioButton android:id="@+id/rad2" android:text="Button2"
                android:layout_width="105px" android:textSize="13px"
                android:layout_height="wrap_content" />
            <RadioButton android:id="@+id/rad3" android:text="Button3"
                android:layout_width="105px" android:textSize="13px"
                android:layout_height="wrap_content" />
    </TableRow>
    <TableRow>
            <RadioButton android:id="@+id/rad1" android:text="Button1"
                android:layout_width="105px" android:layout_height="wrap_content"
                android:textSize="13px" />
            <RadioButton android:id="@+id/rad2" android:text="Button2"
                android:layout_width="105px" android:textSize="13px"
                android:layout_height="wrap_content" />
            <RadioButton android:id="@+id/rad3" android:text="Button3"
                android:layout_width="105px" android:textSize="13px"
                android:layout_height="wrap_content" />
    </TableRow>
</com.codtech.android.view.ToggleButtonGroupTableLayout>

Answer 2

After above https://stackoverflow.com/a/2383978/5567009 answer I got another solution for this question, I added some other functionality like, to save the state of the group and also functionality to clear the check functionality like in radio group.

import android.content.Context;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.annotation.IdRes;
import android.util.AttributeSet;
import android.view.View;
import android.widget.RadioButton;
import android.widget.TableLayout;
import android.widget.TableRow;

public class RadioGridGroup extends TableLayout implements View.OnClickListener {

    private static final String TAG = "ToggleButtonGroupTableLayout";
    private int checkedButtonID = -1;

    /**
     * @param context
     */
    public RadioGridGroup(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    /**
     * @param context
     * @param attrs
     */
    public RadioGridGroup(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onClick(View v) {
        if (v instanceof RadioButton) {
            int id = v.getId();
            check(id);
        }
    }

    private void setCheckedStateForView(int viewId, boolean checked) {
        View checkedView = findViewById(viewId);
        if (checkedView != null && checkedView instanceof RadioButton) {
            ((RadioButton) checkedView).setChecked(checked);
        }
    }

    /* (non-Javadoc)
     * @see android.widget.TableLayout#addView(android.view.View, int, android.view.ViewGroup.LayoutParams)
     */
    @Override
    public void addView(View child, int index,
                        android.view.ViewGroup.LayoutParams params) {
        super.addView(child, index, params);
        setChildrenOnClickListener((TableRow) child);
    }


    /* (non-Javadoc)
     * @see android.widget.TableLayout#addView(android.view.View, android.view.ViewGroup.LayoutParams)
     */
    @Override
    public void addView(View child, android.view.ViewGroup.LayoutParams params) {
        super.addView(child, params);
        setChildrenOnClickListener((TableRow) child);
    }


    private void setChildrenOnClickListener(TableRow tr) {
        final int c = tr.getChildCount();
        for (int i = 0; i < c; i++) {
            final View v = tr.getChildAt(i);
            if (v instanceof RadioButton) {
                v.setOnClickListener(this);
            }
        }
    }


    /**
     * @return the checked button Id
     */
    public int getCheckedRadioButtonId() {
        return checkedButtonID;
    }


    /**
     * Check the id
     *
     * @param id
     */
    public void check(@IdRes int id) {
        // don't even bother
        if (id != -1 && (id == checkedButtonID)) {
            return;
        }
        if (checkedButtonID != -1) {
            setCheckedStateForView(checkedButtonID, false);
        }
        if (id != -1) {
            setCheckedStateForView(id, true);
        }
        setCheckedId(id);
    }

    /**
     * set the checked button Id
     *
     * @param id
     */
    private void setCheckedId(int id) {
        this.checkedButtonID = id;
    }

    public void clearCheck() {
        check(-1);
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        if (!(state instanceof SavedState)) {
            super.onRestoreInstanceState(state);
            return;
        }

        SavedState ss = (SavedState) state;
        super.onRestoreInstanceState(ss.getSuperState());

        this.checkedButtonID = ss.buttonId;
        setCheckedStateForView(checkedButtonID, true);
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        Parcelable superState = super.onSaveInstanceState();
        SavedState savedState = new SavedState(superState);
        savedState.buttonId = checkedButtonID;
        return savedState;
    }

    static class SavedState extends BaseSavedState {
        int buttonId;

        /**
         * Constructor used when reading from a parcel. Reads the state of the superclass.
         *
         * @param source
         */
        public SavedState(Parcel source) {
            super(source);
            buttonId = source.readInt();
        }

        /**
         * Constructor called by derived classes when creating their SavedState objects
         *
         * @param superState The state of the superclass of this view
         */
        public SavedState(Parcelable superState) {
            super(superState);
        }

        @Override
        public void writeToParcel(Parcel out, int flags) {
            super.writeToParcel(out, flags);
            out.writeInt(buttonId);
        }

        public static final Parcelable.Creator<SavedState> CREATOR =
                new Parcelable.Creator<SavedState>() {
                    public SavedState createFromParcel(Parcel in) {
                        return new SavedState(in);
                    }

                    public SavedState[] newArray(int size) {
                        return new SavedState[size];
                    }
                };
    }
}

and use this in XML as follows

<com.test.customviews.RadioGridGroup xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <TableRow android:layout_marginTop="@dimen/preview_five">

        <RadioButton
            android:id="@+id/rad1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button1" />

        <RadioButton
            android:id="@+id/rad2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button2" />
    </TableRow>

    <TableRow android:layout_marginTop="@dimen/preview_five">

        <RadioButton
            android:id="@+id/rad3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button3" />

        <RadioButton
            android:id="@+id/rad4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button4" />
    </TableRow>

    <TableRow android:layout_marginTop="@dimen/preview_five">

        <RadioButton
            android:id="@+id/rad5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button5" />

        <RadioButton
            android:id="@+id/rad6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button6" />
    </TableRow>

    <TableRow android:layout_marginTop="@dimen/preview_five">

        <RadioButton
            android:id="@+id/rad7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button7" />

        <RadioButton
            android:id="@+id/rad8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Button8" />
    </TableRow>
</com.test.customviews.RadioGridGroup>

For any other improvements, please comment.

Answer 3

This uses a custom GridLayout with the RadioGroup functionality. Thanks to Saikrishnan Ranganathan for saiaspire/RadioGridGroup

<com.sample.RadioGridGroup
        xmlns:grid="http://schemas.android.com/apk/res-auto"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        grid:columnCount="3"
        grid:useDefaultMargins="true">

        <android.support.v7.widget.AppCompatRadioButton
            android:checked="true"
            android:text="Text1"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text2"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text3"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text4"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text5"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text6"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text7"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text8"
            grid:layout_columnWeight="1"/>

        <android.support.v7.widget.AppCompatRadioButton
            android:text="Text9"
            grid:layout_columnWeight="1"/>

    </com.sample.RadioGridGroup>

Answer 4

I've written a very simple GridLayout subclass that acts like a RadioGroup . This is how it looks:

To use it first add the GridLayout library:

implementation "androidx.gridlayout:gridlayout:1.0.0-beta01"

Then copy-paste the GridLayout subclass:

/**
 * A GridLayout subclass that acts like a RadioGroup. Important: it only accepts RadioButton as children.
 * Inspired by https://stackoverflow.com/a/2383978/4034572
 */
class GridRadioGroup @JvmOverloads constructor(
        context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : GridLayout(context, attrs, defStyleAttr), View.OnClickListener {

    @IdRes var selectedRadioButtonId: Int? = null
    get() = getSelectedRadioButton()?.id
    private set

    private fun getSelectedRadioButton(): RadioButton? {
        for (index in 0 until childCount) {
            val radioButton = getChildAt(index) as RadioButton
            if (radioButton.isChecked) return radioButton
        }
        return null
    }

    override fun onClick(view: View) {
        // While this looks inefficient, it does fix a bug (2 RadioButtons could be selected at the
        // same time) when navigating back by popping-up a fragment from the backstack.
        for (index in 0 until childCount) {
            val radioButton = getChildAt(index) as RadioButton
            radioButton.isChecked = false
        }
        val radioButton = view as RadioButton
        radioButton.isChecked = true
    }

    override fun addView(child: View?, index: Int, params: ViewGroup.LayoutParams?) {
        super.addView(child, index, params)
        child?.setOnClickListener(this)
    }

}

Finally just use it:

<com.example.ui.GridRadioGroup
    android:id="@+id/gridRadioGroup"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:columnCount="2"
    >

    <RadioButton
        android:id="@+id/option_1"
        style="@style/GridRadioButton"
        android:drawableTop="@drawable/option_1"
        android:text="@string/register_choose_goal_option_1"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1"
        />

    <RadioButton
        android:id="@+id/option_2"
        style="@style/GridRadioButton"
        android:drawableTop="@drawable/option_2"
        android:text="@string/option_2"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1"
        tools:checked="true"
        />

    <RadioButton
        android:id="@+id/option_3"
        style="@style/GridRadioButton"
        android:drawableTop="@drawable/option_3"
        android:text="@string/option_3"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1"
        tools:checked="true"
        />

    <RadioButton
        android:id="@+id/option_4"
        style="@style/GridRadioButton"
        android:drawableTop="@drawable/preparar_carrera"
        android:text="@string/option_4"
        app:layout_columnWeight="1"
        app:layout_rowWeight="1"
        />

</com.example.ui.GridRadioGroup>

The style:

<style name="GridRadioButton">
    <item name="android:layout_width">0dp</item>
    <item name="android:layout_height">wrap_content</item>
    <item name="android:layout_margin">10dp</item>
    <item name="android:background">@drawable/button_option_background_selector</item>
    <item name="android:drawablePadding">16dp</item>
    <item name="android:button">@null</item>
    <item name="android:gravity">center_horizontal</item>
    <item name="android:padding">20dp</item>
    <item name="android:textColor">@drawable/text_button_option_color_selector</item>
    <item name="android:textSize">14sp</item>
</style>

The code is simple but it's working fine for me. If you want something more complete (with for example an OnCheckedChangeListener ) then check this alternative implementation which is clearly more elaborate and on par feature-wise with a RadioGroup .

Answer 5

I for one would go for nested RadioGroups. The Root RadioGroup will have a Vertical orientation and its children will be three RadioGroups with Horizontal orientation.

<RadioGroup
    android:orientation="vertical">
    <RadioGroup
        android:id="@+id/rg_1"
        android:orientation="horizontal">
        <RadioButton />
        <RadioButton />
        <RadioButton />
    </RadioGroup>
    <RadioGroup
        android:id="@id/rg_2"
        android:orientation="horizontal">
        <RadioButton />
        <RadioButton />
        <RadioButton />
    </RadioGroup>
    <RadioGroup
        android:id="@+id/rg_3"
        android:orientation="horizontal">
        <RadioButton />
        <RadioButton />
        <RadioButton />
    </RadioGroup>
</RadioGroup>

Each of the chield RadioGroups will have an ID which will be called by a RadioGroup object inside the java validation method. Like this:

RadioGroup rg_1 = (RadioGroup) findViewById(R.id.rg_1);
RadioGroup rg_2 = (RadioGroup) findViewById(R.id.rg_2);
RadioGroup rg_3 = (RadioGroup) findViewById(R.id.rg_3);

Now simply by using clearCheck() inside the switch case you can clear the check of the other two RadioGroups. Like this:

case R.id.radioButton_1:
            if (checked) {
                rg_2.clearCheck();
                rg_3.clearCheck();
            }
            break;

Answer 6

Your only option is to grab the source code to RadioGroup and attempt to replicate its functionality in a TableLayout or something. There is no way to create a 3x3 grid of RadioButtons otherwise. Fortunately, the RadioButton class does not know about RadioGroup -- all of the mutual-exclusion logic is in RadioGroup . Hence, it should be possible to create a RadioGrid or something...but that's going to be an awful lot of work.

Answer 7

RadioGroup extends in the following manner..

java.lang.Object
 ↳  android.view.View
   ↳    android.view.ViewGroup
       ↳    android.widget.LinearLayout
           ↳    android.widget.RadioGroup

If you need to arrange the radio button in a grid layout, you might need to build you own custom code that extends from GridLayout .

Answer 8

It's a cludge but why not Why not just use nine RadioGroups, or three horizontal RadioGroups each with three buttons. Each radio group can then be aligned with a gridView, or relativeLayout etc.

The then instead of using the standard OnCheckedChangeListener of RadioButton use the one (of the same name) belonging to the CompoundButton instead.

Then when ever any RadioButton is pressed you can use the radio groups to deselect the radio buttons. Then programmatically select the radio button that was clicked.

It's a horrible solution, but it works as one would hope it to.

Below is some example code I used to do this with a 2x2 layout of buttons.

  public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        updateList(Hurricane.ELEVATION_ALL);

        watermarkAdapter = new WatermarkAdapter(getActivity(), R.layout.watermark_item, 
                           relatedHurricanes);

        setListAdapter(watermarkAdapter);

        this.getListView().setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
        this.getView().setBackgroundResource(R.drawable.splash_screen1);


        getListView().setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);


        View v = this.getView();
        filterGroup1 = (RadioGroup)v.findViewById(R.id.filter_rg1);
        filterGroup2 = (RadioGroup)v.findViewById(R.id.filter_rg2);
        filterGroup3 = (RadioGroup)v.findViewById(R.id.filter_rg3);
        filterGroup4 = (RadioGroup)v.findViewById(R.id.filter_rg4);


        rb1 = (RadioButton) v.findViewById(R.id.first_radio_button);//All
        rb2 = (RadioButton) v.findViewById(R.id.second_radio_button);//0-6
        rb4 = (RadioButton) v.findViewById(R.id.third_radio_button);//6-12
        rb3 = (RadioButton) v.findViewById(R.id.fourth_radio_button);//>=5

        rb1.setOnCheckedChangeListener(this);
        rb2.setOnCheckedChangeListener(this);
        rb3.setOnCheckedChangeListener(this);
        rb4.setOnCheckedChangeListener(this);


    }






 @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

        filterGroup1.clearCheck();
        filterGroup2.clearCheck();
        filterGroup3.clearCheck();
        filterGroup4.clearCheck();


        SharedPreferences prefs = PreferenceManager
                .getDefaultSharedPreferences(this.getActivity());

       int cid = buttonView.getId();

       Editor editor     = prefs.edit();
       int elevation = Hurricane.ELEVATION_ALL;
        //All
       if(rb1.getId() == cid){
          elevation = Hurricane.ELEVATION_ALL;
       }  
       //0-6
       else if(rb2.getId() == cid){
           elevation = Hurricane.ELEVATION_6to12;
       }
       //6-12
       else if(rb3.getId() == cid){       
           elevation = Hurricane.ELEVATION_0to6;
       }
       //>=12
       else if(rb4.getId() == cid){
           elevation = Hurricane.ELEVATION_GT12;
       }

       update(StormFragment.NORMAL, elevation);

    }

Answer 9

A simpler approach of my point of view is to use a RecyclerView .
The ViewHolder will contains only one RadioButton .
The data class will contain a string attribute to display, and an additional boolean attribute to switch the isChecked state.
Inside the ViewHolder , we will switch the state inside an onClickListener .
The RecyclerViewAdapter will contain an additional function to get the selected item.

Code Example

BloodType.kt

data class BloodType(val name: String, var isChecked: Boolean)

item_blood_type.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <RadioButton
        android:id="@+id/rb_item_blood_type"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        tools:text="RadioButton"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

BloodTypeAdapter.kt

class BloodTypeAdapter(val data: List<BloodType>) :
    RecyclerView.Adapter<BloodTypeAdapter.BloodTypeHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BloodTypeHolder {
        val view =
            LayoutInflater.from(parent.context).inflate(R.layout.item_blood_type, parent, false)
        return BloodTypeHolder(view)
    }

    override fun onBindViewHolder(holder: BloodTypeHolder, position: Int) {
        holder.itemView.rb_item_blood_type.isChecked = data[position].isChecked
        holder.itemView.rb_item_blood_type.text = data[position].name
    }

    override fun getItemCount(): Int {
        return data.size
    }

    /**
     * @return The selected item from the list.
     */
    fun getCheckedItem(): BloodType {
        data.forEach {
            if (it.isChecked) {
                return it
            }
        }
        return data[0]
    }

    inner class BloodTypeHolder(view: View) : RecyclerView.ViewHolder(view) {
        init {
            itemView.rb_item_blood_type.setOnClickListener {
                data.forEachIndexed { index, bloodType ->
                    bloodType.isChecked = index == adapterPosition
                }
                notifyDataSetChanged()
            }
        }
    }
}

Presenter.kt

//... 
private fun initializeBloodTypeRecyclerView() {
        rvBloodType.layoutManager = GridLayoutManager(context, 2)
        val bloodTypes = mutableListOf<BloodType>()
        bloodTypes.apply {
            add(BloodType("A+", true))
            add(BloodType("A-", false))
            add(BloodType("B+", false))
            //...
        }
        val bloodTypeAdapter = BloodTypeAdapter(bloodTypes)
        rvBloodType.adapter = bloodTypeAdapter
    }
//...

Answer 10

Here is solution

public class RadioGridGroup extends TableLayout implements View.OnClickListener {

private static final String TAG = "ToggleButtonGroupTableLayout";
private int checkedButtonID = -1;
private RadioGridGroup.OnCheckedChangeListener mOnCheckedChangeListener;
/**
 * @param context
 */
public RadioGridGroup(Context context) {
    super(context);
    // TODO Auto-generated constructor stub
}

/**
 * @param context
 * @param attrs
 */
public RadioGridGroup(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
}

@Override
public void onClick(View v) {
    if (v instanceof RadioButton) {
        int id = v.getId();
        check(id);
    }
}

private void setCheckedStateForView(int viewId, boolean checked) {
    View checkedView = findViewById(viewId);
    if (checkedView != null && checkedView instanceof RadioButton) {
        ((RadioButton) checkedView).setChecked(checked);
    }
}

/* (non-Javadoc)
 * @see android.widget.TableLayout#addView(android.view.View, int, android.view.ViewGroup.LayoutParams)
 */
@Override
public void addView(View child, int index,
                    android.view.ViewGroup.LayoutParams params) {
    super.addView(child, index, params);
    setChildrenOnClickListener((TableRow) child);
}


/* (non-Javadoc)
 * @see android.widget.TableLayout#addView(android.view.View, android.view.ViewGroup.LayoutParams)
 */
@Override
public void addView(View child, android.view.ViewGroup.LayoutParams params) {
    super.addView(child, params);
    setChildrenOnClickListener((TableRow) child);
}


private void setChildrenOnClickListener(TableRow tr) {
    final int c = tr.getChildCount();
    for (int i = 0; i < c; i++) {
        final View v = tr.getChildAt(i);
        if (v instanceof RadioButton) {
            v.setOnClickListener(this);
        }
    }
}


/**
 * @return the checked button Id
 */
public int getCheckedRadioButtonId() {
    return checkedButtonID;
}


/**
 * Check the id
 *
 * @param id
 */
public void check(@IdRes int id) {
    // don't even bother
    if (id != -1 && (id == checkedButtonID)) {
        return;
    }
    if (checkedButtonID != -1) {
        setCheckedStateForView(checkedButtonID, false);
    }
    if (id != -1) {
        setCheckedStateForView(id, true);
    }
    setCheckedId(id);
}

/**
 * set the checked button Id
 *
 * @param id
 */
private void setCheckedId(int id) {
    if (mOnCheckedChangeListener != null) {
        mOnCheckedChangeListener.onCheckedChanged(this, id);
    }
    this.checkedButtonID = id;
}

public void clearCheck() {
    check(-1);
}

@Override
protected void onRestoreInstanceState(Parcelable state) {
    if (!(state instanceof SavedState)) {
        super.onRestoreInstanceState(state);
        return;
    }

    SavedState ss = (SavedState) state;
    super.onRestoreInstanceState(ss.getSuperState());

    this.checkedButtonID = ss.buttonId;
    setCheckedStateForView(checkedButtonID, true);
}

@Override
protected Parcelable onSaveInstanceState() {
    Parcelable superState = super.onSaveInstanceState();
    SavedState savedState = new SavedState(superState);
    savedState.buttonId = checkedButtonID;
    return savedState;
}

static class SavedState extends BaseSavedState {
    int buttonId;

    /**
     * Constructor used when reading from a parcel. Reads the state of the superclass.
     *
     * @param source
     */
    public SavedState(Parcel source) {
        super(source);
        buttonId = source.readInt();
    }

    /**
     * Constructor called by derived classes when creating their SavedState objects
     *
     * @param superState The state of the superclass of this view
     */
    public SavedState(Parcelable superState) {
        super(superState);
    }

    @Override
    public void writeToParcel(Parcel out, int flags) {
        super.writeToParcel(out, flags);
        out.writeInt(buttonId);
    }

    public static final Parcelable.Creator<SavedState> CREATOR =
            new Parcelable.Creator<SavedState>() {
                public SavedState createFromParcel(Parcel in) {
                    return new SavedState(in);
                }

                public SavedState[] newArray(int size) {
                    return new SavedState[size];
                }
            };
}
public void setOnCheckedChangeListener(RadioGridGroup.OnCheckedChangeListener listener) {
    mOnCheckedChangeListener = listener;
}
public interface OnCheckedChangeListener {

    public void onCheckedChanged(RadioGridGroup group, @IdRes int checkedId);
}}

Click Listener

    RadioGridGroup radioGroup = findViewById(R.id.radioGroup);
   
    radioGroup.setOnCheckedChangeListener(new RadioGridGroup.OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(RadioGridGroup group, int checkedId) {
            
            if (checkedId == R.id.radio6) {
                
            }
        }

    });

XML

<com.customviews.RadioGridGroup 
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content">

<TableRow android:layout_marginTop="@dimen/preview_five">

    <RadioButton
        android:id="@+id/rad1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button1" />

    <RadioButton
        android:id="@+id/rad2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button2" />
</TableRow>

<TableRow android:layout_marginTop="@dimen/preview_five">

    <RadioButton
        android:id="@+id/rad3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button3" />

    <RadioButton
        android:id="@+id/rad4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button4" />
</TableRow>

<TableRow android:layout_marginTop="@dimen/preview_five">

    <RadioButton
        android:id="@+id/rad5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button5" />

    <RadioButton
        android:id="@+id/rad6"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button6" />
</TableRow>

<TableRow android:layout_marginTop="@dimen/preview_five">

    <RadioButton
        android:id="@+id/rad7"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button7" />

    <RadioButton
        android:id="@+id/rad8"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button8" />
</TableRow>
</com.customviews.RadioGridGroup>

Note : Make sure all radio buttons must be under TableRow.