A Quiz Activity with Scores from CheckBoxex, RadioButtons and EditText

QuizActivity.java

package com.example.android.quizz;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private static int score = 0;

    private RadioGroup radioGroupAnimal;

    private EditText editTextContinent;

    private CheckBox chkBxNileRiver;
    private CheckBox chkBxZambeziRiver;
    private CheckBox chkBxNepalRiver;

    private boolean isChoiceMammal = false;
    private boolean isChoiceNile = false;

    private CompoundButton.OnCheckedChangeListener chkCheckedListner;
    private RadioGroup.OnCheckedChangeListener radioCheckChangeListener;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the CheckBoxes
        chkBxNileRiver = (CheckBox) findViewById(R.id.nileriver);
        chkBxZambeziRiver = (CheckBox) findViewById(R.id.zambeziriver);
        chkBxNepalRiver = (CheckBox) findViewById(R.id.nepalriver);
        // Initialize EditText
        editTextContinent = (EditText) findViewById(R.id.et_continent);
        // Initialize the RadioGroup
        radioGroupAnimal = (RadioGroup) findViewById(R.id.animal);

        setListeners();
    }


    public void setListeners() {

        // CheckBox listeners
        chkCheckedListner = new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton selectedCheckBox, boolean isChecked) {
                // Check which checkbox was clicked
                switch (selectedCheckBox.getId()) {
                    case R.id.nileriver:
                        if (isChecked) {
                            isChoiceNile = true;
                        }
                        break;
                    case R.id.zambeziriver:
                        if (isChecked) {
                            isChoiceNile = false;
                        }
                        break;
                    case R.id.nepalriver:
                        if (isChecked) {
                            isChoiceNile = false;
                        }
                        break;
                }
            }
        };

        chkBxNileRiver.setOnCheckedChangeListener(chkCheckedListner);
        chkBxZambeziRiver.setOnCheckedChangeListener(chkCheckedListner);
        chkBxNepalRiver.setOnCheckedChangeListener(chkCheckedListner);

        // RadioGroup Listeners
        radioCheckChangeListener = new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int radioButtonId) {
                switch (radioGroup.getId()) {
                    case R.id.animal:
                        if (R.id.radio_mammal == radioButtonId) {
                            isChoiceMammal = false;
                        }

                        if (R.id.radio_reptile == radioButtonId) {
                            isChoiceMammal = true;
                        }
                        break;
                }
            }
        };

        radioGroupAnimal.setOnCheckedChangeListener(radioCheckChangeListener);
    }


    public void display(String message) {

        TextView ScoreView = (TextView) findViewById(R.id.socre_view);
        ScoreView.setText(message);
        ScoreView.setHighlightColor(Color.YELLOW);
    }

    public void submit(View view) {

        if (isChoiceMammal) {
            score = +1;
        }
        if (isChoiceMammal) {
            score += 1;
        }
        if (isChoiceNile) {
            score += 1;
        }

        String continentAnswer = editTextContinent.getText().toString();
        if (continentAnswer == "London") {
            score += 1;
        }

        display("Your Score Is: " + score);
    }

    public void reset(View view) {
        score = 0;

        isChoiceMammal = false;
        isChoiceNile = false;

        // Reset all CheckBoxes
        chkBxNileRiver.setChecked(false);
        chkBxZambeziRiver.setChecked(false);
        chkBxNepalRiver.setChecked(false);
        // Reset all RadioButtons
        for (int i = 0; i < radioGroupAnimal.getChildCount(); i++) {

            RadioButton childButton = (RadioButton) radioGroupAnimal.getChildAt(i);
            childButton.setChecked(false);
        }

        display("Your Score Is:" + score);
    }
}

Thank you Master!

hi, pls can i see code for your xml?