Radio Buttons: Listener in XML or JAVA?

I decided to make an app in android for my science exhibition and I have reached a dead end! I am trying to make a unit converter using radio buttons as the unit selection method. All is fine but when I select another radio button, the app crashes! I have no idea what is going on? Here is my layout:

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://ift.tt/nIICcg"
android:id="@+id/TableLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="30dp" >

<RadioGroup
    android:id="@+id/from"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="left" >

    <RadioButton
        android:id="@+id/km"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"
        android:onClick="radioClicked"
        android:text="KiloMeters" />

    <RadioButton
        android:id="@+id/m"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="radioClicked"
        android:text="Meters" />

    <RadioButton
        android:id="@+id/cm"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="radioClicked"
        android:text="Centimeters" />

</RadioGroup>

<Space
    android:id="@+id/Space1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="fill_vertical" />

<EditText
    android:id="@+id/KmValue"
    android:layout_width="115dp"
    android:layout_height="wrap_content"
    android:layout_marginBottom="24dp"
    android:layout_marginLeft="0dp"
    android:ems="10"
    android:inputType="numberDecimal" />

<RadioGroup
    android:id="@+id/to"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

    <RadioButton
        android:id="@+id/mTo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="38dp"
        android:checked="true"
        android:onClick="radioClicked"
        android:text="Meters" />

    <RadioButton
        android:id="@+id/cmTo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="radioClicked"
        android:text="Cenitmeters" />

    <RadioButton
        android:id="@+id/mmTo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="radioClicked"
        android:text="Millimeters" />
</RadioGroup>

<TextView
    android:id="@+id/MValue"
    android:layout_width="96dp"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<Button
    android:id="@+id/cButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Convert" />

</TableLayout>

And here is my Java Activity:

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.Toast;

public class LengthFragment extends Fragment {

public LengthFragment(){}
double ratio = 1000;
int x=1;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_length, container, false);

    final EditText km = (EditText) rootView.findViewById(R.id.KmValue);
    final TextView meter = (TextView) rootView.findViewById(R.id.MValue);
    Button convert = (Button) rootView.findViewById(R.id.cButton);

    convert.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            if(km.getText().toString().isEmpty()) {
                 Toast.makeText(getActivity(), "Enter Something Buddy!", Toast.LENGTH_SHORT).show();
            } else {
                float k = Float.parseFloat(km.getText().toString());
                double m = k*ratio;
                meter.setText(""+m);
            }
        }

    });
    return rootView;
}

public void radioClicked(View view) {
    boolean checked = ((RadioButton) view).isChecked();
    switch(view.getId()) {
        case R.id.km:
            if (checked)
                x=1;
            break;
        case R.id.m:
            if (checked) {
                x=2;
            }
            break;
        case R.id.cm:
            if (checked)
                x=3;
            break;
        case R.id.mTo:
            if (checked)
                if(x==1) {
                    ratio=1000;
                }
                else if(x==2) {
                    ratio=1;
                }
                else if(x==3) {
                    ratio=0.01;
                }else {

                }
            break;
        case R.id.cmTo:
            if (checked)
                if(x==1) {
                    ratio=100000;
                }
                else if(x==2) {
                    ratio=100;
                }
                else if(x==3) {
                    ratio=1;
                }else {

                }

            break;
        case R.id.mmTo:
            if (checked)
                if(x==1) {
                    ratio=1000000;
                }
                else if(x==2) {
                    ratio=1000;
                }
                else if(x==3) {
                    ratio=10;
                }else {

                }

            break;
    }

}

}

I could post whatever maybe required for the answer. Please help!