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

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 2

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>