I'm learning to code Android apps and have recently finished a quiz app. I would like some feedback about best practices and possible ways to improve performance, as I'm also new to Java.
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
tools:context="com.example.android.mathquiz.MainActivity"
android:background="#C5CAE9">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:focusable="true"
android:focusableInTouchMode="true"
android:gravity="center_horizontal"
android:orientation="vertical"
android:paddingBottom="16dp"
android:paddingLeft="16dp"
android:paddingRight="16dp">
<TextView
style="@style/AllElements"
android:text="Respondé las siguientes preguntas:" />
<!-- QUESTION 1 [DONE]-->
<TextView
style="@style/Questions"
android:text="1) La pendiente de una recta es su inclinación." />
<RadioGroup
style="@style/AllElements"
android:id="@+id/question_one_answers"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<RadioButton
android:id="@+id/question_one_answer_one"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Verdadero"/>
<RadioButton
android:id="@+id/question_one_answer_two"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Falso"/>
</RadioGroup>
<!-- QUESTION 2 [LISTO]-->
<TextView
style="@style/Questions"
android:text="2) Indicar la ordenada al origen de la función:\ny = x" />
<EditText
style="@style/AllElements"
android:id="@+id/question_two_answer"
android:layout_width="match_parent"
android:inputType="number"
android:hint="Respuesta"/>
<!-- QUESTION 3 [LISTO]-->
<TextView
style="@style/Questions"
android:text="3) Indicar la pendiente de la función:\ny = x + 1" />
<EditText
style="@style/AllElements"
android:id="@+id/question_three_answer"
android:layout_width="match_parent"
android:inputType="number"
android:hint="Respuesta"/>
<!-- QUESTION 4 -->
<TextView
style="@style/Questions"
android:layout_marginBottom="0dp"
android:text="4) ¿Cuáles son los requisitos de las funciones?" />
<TextView
style="@style/AllElements"
android:layout_marginBottom="32dp"
android:text="Seleccionar todas las opciones posibles." />
<CheckBox
android:id="@+id/question_four_answer_one"
style="@style/AllElements"
android:text="Unicidad" />
<CheckBox
android:id="@+id/question_four_answer_two"
style="@style/AllElements"
android:text="Positividad" />
<CheckBox
android:id="@+id/question_four_answer_three"
style="@style/AllElements"
android:text="Existencia" />
<!-- CHECK ANSWERS -->
<Button
style="@style/AllElements"
android:text="Revisar"
android:layout_marginBottom="8dp"
android:layout_marginTop="36dp"
android:onClick="checkAnswers"/>
</LinearLayout>
</ScrollView>
MainActivity.java:
public class MainActivity extends AppCompatActivity {
String[] correctAnswers = {"Falso", "0", "1", "Unicidad Existencia"};
RadioGroup questionOneAnswers;
RadioButton questionOneAnswerOne;
RadioButton questionOneAnswerTwo;
EditText questionTwoAnswer;
EditText questionThreeAnswer;
CheckBox questionFourAnswerOne;
CheckBox questionFourAnswerTwo;
CheckBox questionFourAnswerThree;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// QUESTION 1
questionOneAnswerOne = (RadioButton) findViewById(R.id.question_one_answer_one);
questionOneAnswerTwo = (RadioButton) findViewById(R.id.question_one_answer_two);
// QUESTION 2
questionTwoAnswer = (EditText) findViewById(R.id.question_two_answer);
// QUESTION 3
questionThreeAnswer = (EditText) findViewById(R.id.question_three_answer);
// QUESTION 4
questionFourAnswerOne = (CheckBox) findViewById(R.id.question_four_answer_one);
questionFourAnswerTwo = (CheckBox) findViewById(R.id.question_four_answer_two);
questionFourAnswerThree = (CheckBox) findViewById(R.id.question_four_answer_three);
questionOneAnswers = (RadioGroup) findViewById(R.id.question_one_answers);
}
private boolean isEmpty(EditText myeditText) {
return myeditText.getText().toString().trim().length() == 0;
}
private String questionOneGetAnswer() {
if (questionOneAnswerOne.isChecked()) {
return questionOneAnswerOne.getText().toString();
}
else if (questionOneAnswerTwo.isChecked()) {
return questionOneAnswerTwo.getText().toString();
}
else {
return "";
}
}
private String questionTwoGetAnswer() {
if (!isEmpty(questionTwoAnswer)) {
return questionTwoAnswer.getText().toString();
}
else {
return "";
}
}
private String questionThreeGetAnswer() {
if (!isEmpty(questionThreeAnswer)) {
return questionThreeAnswer.getText().toString();
}
else {
return "";
}
}
private String questionFourGetAnswer () {
String returnString = "";
if (questionFourAnswerOne.isChecked()) {
returnString += questionFourAnswerOne.getText();
}
if (questionFourAnswerTwo.isChecked()) {
returnString += " " + questionFourAnswerTwo.getText();
}
if (questionFourAnswerThree.isChecked()) {
returnString += " " + questionFourAnswerThree.getText();
}
return returnString;
}
public void checkAnswers(View view) {
String[] givenAnswers = {questionOneGetAnswer(), questionTwoGetAnswer(), questionThreeGetAnswer(), questionFourGetAnswer()};
int right = 0;
int wrong = 0;
for (int i = 0; i < givenAnswers.length; i++) {
if (givenAnswers[i].equals(correctAnswers[i])) {
right++;
}
else {
wrong++;
}
}
String message;
if (wrong == 0) {
message = "You got all the questions right!";
}
else {
message = "Respuestas correctas: " + right + "\nRespuestas incorrectas: " + wrong + "\n¡Inténtalo de nuevo!";
}
//Reset answer fields
// QUESTION 1
questionOneAnswers.clearCheck();
// QUESTION 2
questionTwoAnswer.setText("");
// QUESTION 3
questionThreeAnswer.setText("");
// QUESTION 4
questionFourAnswerOne.setChecked(false);
questionFourAnswerTwo.setChecked(false);
questionFourAnswerThree.setChecked(false);
// Print out message with quiz results
Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
}
}
styles.xml:
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
<item name="android:textColor">@color/colorAccent</item>
</style>
<style name="AllElements">
<item name="android:layout_width">wrap_content</item>
<item name="android:layout_height">wrap_content</item>
<item name="android:layout_marginTop">16dp</item>
<item name="android:textSize">18sp</item>
<item name="android:textAlignment">center</item>
<item name="android:textColor">#0D47A1</item>
</style>
<style name="Questions" parent="AllElements">
<item name="android:layout_marginBottom">16dp</item>
<item name="android:layout_marginTop">32dp</item>
<item name="android:textSize">26sp</item>
</style>
</resources>
