Android – cannot display the value of a button in a radio button group

I have a simple code below. I don't understand why it doesn't work for me. All I want to do is display (toast) "male" or "female" according to the radio button I click

This is the code of the main activity:

private static  RadioGroup radio_g;
private static  RadioButton radio_b;
private static Button button_sbm;


public void onClickListenerButton() {
    radio_g = (RadioGroup)findViewById(R.id.genderButton);
    button_sbm = (Button)findViewById(R.id.getBMI);

    button_sbm.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int selected_id = radio_g.getCheckedRadioButtonId();
                    radio_b = (RadioButton)findViewById(selected_id);
                    Toast.makeText(MainActivity.this,
                            radio_b.getText().toString(),Toast.LENGTH_SHORT ).show();
                }
            }
    );
}

And broadcast groups:

    <RadioGroup
    android:id="@+id/genderButton"
    android:layout_width="124dp"
    android:layout_height="67dp"
    android:layout_marginLeft="89dp"
    android:layout_marginStart="88dp"
    android:layout_marginTop="63dp"
    android:visibility="visible"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/ageField"
    tools:layout_constraintLeft_creator="1"
    tools:layout_constraintTop_creator="1">

    <RadioButton
        android:id="@+id/maleButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:checked="false"
        android:text="Male"
        tools:text="male" />

    <RadioButton
        android:id="@+id/femaleButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Female"
        tools:text="female" />
</RadioGroup>

Can anyone point out what I lack? This is really frustrating

resolvent:

Your code must look like this:

public class FormActivity extends Activity implements View.OnClickListener {

private static  RadioGroup radio_g;
private static  RadioButton radio_b;
private static Button button_sbm;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_form);
        // initialize component here  like this
  radio_g = (RadioGroup)findViewById(R.id.genderButton);
    button_sbm = (Button)findViewById(R.id.getBMI);

       // Then call listener on button click like this
        button_sbm .setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
    int selected_id = radio_g.getCheckedRadioButtonId();
                    radio_b = (RadioButton)findViewById(selected_id);
                    Toast.makeText(MainActivity.this,
                            radio_b.getText().toString(),Toast.LENGTH_SHORT ).show();
    }

Try this. I'll try it. It's good