Set a variable value on select a radio button from radio group

Question

I want to set a String variable value to 1,2,3 when user selected male, female or unclassified respectively from the radio group.

Right now I am doing it this way but even if I select a radio button it set the variable value as null

Code:

RadioGroup genderGroup;
RadioButton male, female, unclassified;
String strGender;
genderGroup = findViewById(R.id.genderGroup);
male = findViewById(R.id.genderMale);
female = findViewById(R.id.genderFemale);
unclassified = findViewById(R.id.genderUnclassified);

if (genderGroup.getCheckedRadioButtonId() == -1) {
        strGender = null;           //no buttons selected
    } else {
        if (male.isChecked()) {     // one of the radio buttons is checked
            strGender = "1";
        } else if (female.isChecked()) {
            strGender = "2";
        } else if (unclassified.isChecked()) {
            strGender = "3";
        }
    }

When I print the value after selecting any radio button it shows null. If you know how to do this please help :) thanks.

Solved Thanks to Nilesh. Correct code is:

genderGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {

        if (checkedId == R.id.genderMale) {
          strGender = "1";

        } else  if (checkedId == R.id.genderFemale) {
          strGender = "2";
      }

    }
});

Answer 1

you need to use RadioGroup.OnCheckedChangeListener

Interface definition for a callback to be invoked when the checked radio button changed in this group.

radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        if (checkedId == R.id.genderMale) {
            strGender = "1";
        } else  if (checkedId == R.id.genderFemale) {
            strGender = "2";
        }
    }
});