How to check which radio button of a radio group is selected? [ANDROID]

Question

I am using two radio groups with multiple radio buttons, I want to check which radio button is selected so that I can call specific functions accordingly. I am using getCheckedRadioButtonId method to do this, but it's throwing null pointer exception. How this can be done in a correct way? I have tried other methods too. Any help will be appreciated. Here is my code

public class MainActivity extends AppCompatActivity {
private EditText et_name;
private EditText et_age;
private EditText et_contactno;

private RadioGroup radioGroup_gender;
private RadioButton radioButton_male;
private RadioButton radioButton_female;
private RadioGroup radioGroup_methods;
private RadioGroup radioGroup_intent_methods;
private RadioButton radioButton_textfile;
private RadioButton radioButton_sharefpref;
private RadioButton radioButton_database;
private RadioButton radioButton_staticfields;
private RadioButton radioButton_intents;
private RadioButton radioButton_direct;
private RadioButton radioButton_bundle;
private RadioButton radioButton_parcelable;

private String name;
private String age;
private String contact_no;
private String gender;

private int gender_selected_id;
private int transfer_method_selected_id;
private int selected_intent_method_id;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    findViewsByIds();
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "FAB CLICKED", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
            executeSelectedMethod();
        }
    });
}

private void findViewsByIds() {
    et_name = (EditText) findViewById(R.id.et_name);
    et_age = (EditText) findViewById(R.id.et_age);
    et_contactno = (EditText) findViewById(R.id.et_contactno);
    radioGroup_gender = (RadioGroup) findViewById(R.id.rg_gender);
    radioButton_male = (RadioButton) findViewById(R.id.rb_male);
    radioButton_female = (RadioButton) findViewById(R.id.rb_female);

    radioGroup_methods = (RadioGroup) findViewById(R.id.rg_methods);
    radioGroup_intent_methods = (RadioGroup) findViewById(R.id.rg_intentmethods);
    radioButton_textfile = (RadioButton) findViewById(R.id.rb_textfile);
    radioButton_sharefpref = (RadioButton) findViewById(R.id.rb_sharefpref);
    radioButton_database = (RadioButton) findViewById(R.id.rb_database);
    radioButton_staticfields = (RadioButton) findViewById(R.id.rb_static);
    radioButton_intents = (RadioButton) findViewById(R.id.rb_intent);
    radioButton_direct = (RadioButton) findViewById(R.id.rb_intent_direct);
    radioButton_bundle = (RadioButton) findViewById(R.id.rb_intent_bundle);
    radioButton_parcelable = (RadioButton) findViewById(R.id.rb_intent_parcelable);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

private void executeSelectedMethod() {
    try {
        name = et_name.getText().toString();
        age = et_age.getText().toString();
        contact_no = et_contactno.getText().toString();
        RadioButton rb = (RadioButton) findViewById(radioGroup_gender.getCheckedRadioButtonId());
        String selectedgender = rb.getText().toString();
        if (selectedgender.equalsIgnoreCase("Male")) {
            gender = radioButton_male.getText().toString();
        } else if (selectedgender.equalsIgnoreCase("Female")) {
            gender = radioButton_female.getText().toString();
        }
        RadioButton rb_selected_method = (RadioButton) findViewById(radioGroup_gender.getCheckedRadioButtonId());
        String selectedRadioButtontext = rb_selected_method.getText().toString();
        if (selectedRadioButtontext.equalsIgnoreCase("Text File")) {
            ConstantFile.TRANSFER_METHOD = radioButton_textfile.getText().toString();
            executeTextFileMethod();
        } else if (transfer_method_selected_id == R.id.rb_sharefpref) {
            ConstantFile.TRANSFER_METHOD = radioButton_sharefpref.getText().toString();
        } else if (transfer_method_selected_id == R.id.rb_database) {
            ConstantFile.TRANSFER_METHOD = radioButton_database.getText().toString();
        } else if (transfer_method_selected_id == R.id.rb_static) {
            ConstantFile.TRANSFER_METHOD = radioButton_staticfields.getText().toString();
        } else {

            selected_intent_method_id = radioGroup_intent_methods.getCheckedRadioButtonId();
            if (selected_intent_method_id == R.id.rb_intent_direct) {
                ConstantFile.TRANSFER_METHOD = radioButton_direct.getText().toString();
            } else if (selected_intent_method_id == R.id.rb_intent_bundle) {
                ConstantFile.TRANSFER_METHOD = radioButton_bundle.getText().toString();

            } else if (selected_intent_method_id == R.id.rb_intent_parcelable) {
                ConstantFile.TRANSFER_METHOD = radioButton_parcelable.getText().toString();

            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void executeTextFileMethod() throws IOException {
    File transfer_file = new File("/sdcard/" + name + ".txt");
    transfer_file.createNewFile();
    FileOutputStream fileoutputstrem = new FileOutputStream(transfer_file);
    OutputStreamWriter outstreamwriter = new OutputStreamWriter(fileoutputstrem);
    outstreamwriter.append(name + ":" + age + ":" + contact_no + ":" + gender);
    fileoutputstrem.close();
    outstreamwriter.close();
    Toast.makeText(this, "This is my Toast message!",
            Toast.LENGTH_LONG).show();
    ConstantFile.TXTFILENAME = transfer_file.getName();
    goToNextActivity();
}

private void goToNextActivity() {
    Intent intent = new Intent(MainActivity.this, Main2Activity.class);
    startActivity(intent);
}}

This is the exception:

Process: com.phaseone_datatransferbetweenactivities, PID: 22385
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.widget.RadioButton.getText()' on a null object reference
at com.phaseone_datatransferbetweenactivities.MainActivity.executeSelectedMethod(MainActivity.java:118)
at com.phaseone_datatransferbetweenactivities.MainActivity.access$000(MainActivity.java:23)
at com.phaseone_datatransferbetweenactivities.MainActivity$1.onClick(MainActivity.java:65)
at android.view.View.performClick(View.java:5265)
at android.view.View$PerformClick.run(View.java:21534)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5728)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)

Answer 1

This is working perfectly:

RadioGroup radioGroup = (RadioGroup) findViewById(R.id.radio_group);

int radioButtonID = radioGroup.getCheckedRadioButtonId();

RadioButton radioButton = (RadioButton) radioGroup.findViewById(radioButtonID);

String selectedText = (String) radioButton.getText();