我想就我的 android 代碼尋求一些幫助。我正在嘗試使用 SQLite 開發一個測驗應用程式。可能的答案數量不同，所以如果答案是 3 而不是 4，我需要從主螢屏隱藏單選按鈕（默認情況下，4 是單選按鈕的數量）。嘗試使用：
if (DataContract.QuestionTable.COLUMN_ANSWER4.isEmpty ()){ radioButton4.setVisibility (View.INVISIBLE); }
但似乎不起作用。我是 android 編程新手，這是我的第一個專案，所以每條評論都會很有幫助。謝謝你。
這是我的代碼的一部分：
測驗活動的xml
`<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#C8ECF1"
android:backgroundTint="#C2ECF1"
android:backgroundTintMode="src_atop"
android:fadingEdge="horizontal"
tools:context=".QuestionsAct">
<TextView
android:id="@ id/tvQuestionCount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="5dp"
android:layout_marginTop="5dp"
android:text="question 1/x"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@ id/tVTime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginEnd="16dp"
android:text="30:00"
android:textSize="20sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<RadioGroup
android:id="@ id/radioGroup"
android:layout_width="356dp"
android:layout_height="202dp"
android:layout_marginBottom="40dp"
app:layout_constraintBottom_toTopOf="@ id/butConfirmAns"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.29"
app:layout_constraintStart_toStartOf="parent">
<RadioButton
android:id="@ id/radioButton1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="24dp"
android:hint="answear1"
android:textAlignment="viewStart"
android:textStyle="bold" />
<RadioButton
android:id="@ id/radioButton2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="24dp"
android:hint="answer2"
android:textAlignment="viewStart"
android:textStyle="bold" />
<RadioButton
android:id="@ id/radioButton3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="24dp"
android:hint="answer3"
android:textAlignment="viewStart"
android:textStyle="bold" />
<RadioButton
android:id="@ id/radioButton4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="24dp"
android:textAlignment="viewStart"
android:textStyle="bold"
/>
</RadioGroup>
<TextView
android:id="@ id/tVQuestion"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="5dp"
android:text="Question bla bla "
android:textSize="20sp"
app:layout_constraintBottom_toTopOf="@ id/radioGroup"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@ id/tvImgQuest"
app:layout_constraintVertical_bias="0.139" />
<Button
android:id="@ id/butConfirmAns"
android:layout_width="wrap_content"
android:layout_height="35dp"
android:layout_marginStart="15dp"
android:layout_marginBottom="36dp"
android:background="#FF9800"
android:text="Submit"
android:textColor="#009688"
android:textSize="12sp"
android:textStyle="bold"
app:iconTint="#DA9E45"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toEndOf="@ id/butBack"
app:strokeColor="#8BC34A" />
<ImageView
android:id="@ id/tvImgQuest"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:visibility="visible"
app:layout_constraintBottom_toTopOf="@ id/radioGroup"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.176"
app:srcCompat="@drawable/ic_launcher_background" />
<Button
android:id="@ id/butBack"
android:layout_width="61dp"
android:layout_height="33dp"
android:layout_marginStart="4dp"
android:layout_marginBottom="36dp"
android:textSize="12sp"
app:icon="@android:drawable/ic_media_rew"
app:iconTint="#2196F3"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<Button
android:id="@ id/butForw"
android:layout_width="61dp"
android:layout_height="35dp"
android:layout_marginStart="15dp"
android:layout_marginBottom="36dp"
android:textSize="12sp"
android:textStyle="bold"
app:icon="@android:drawable/ic_media_ff"
app:iconTint="#2196F3"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toEndOf="@ id/butConfirmAns" />
<Button
android:id="@ id/butFinish"
android:layout_width="85dp"
android:layout_height="35dp"
android:layout_marginStart="30dp"
android:layout_marginEnd="10dp"
android:layout_marginBottom="36dp"
android:text="Finish"
android:textAlignment="center"
android:textColor="#F44336"
android:textSize="10sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toEndOf="@ id/butForw" />
<TextView
android:id="@ id/tvScore"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="4dp"
android:layout_marginTop="28dp"
android:text="Score: 0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@ id/tvQuestionCount" />
</androidx.constraintlayout.widget.ConstraintLayout>`
資料庫表
`package com.anna.myquiz;
import android.provider.BaseColumns;
public final class DataContract {
private DataContract(){}
public static class StudentTable implements BaseColumns {
public static final String TABLE_NAME1 = "student_info";
public static final String COLUMN_ID = "id";
public static final String COLUMN_AM = "studentAm";
public static final String COLUMN_NAME = "name";
public static final String COLUMN_SEMESTER = "semester";
public static final String COLUMN_SCORE = "score";
public static final String COLUMN_DATE = "studentDate";
}
public static class QuestionTable implements BaseColumns {
public static final String TABLE_NAME = "quiz_question";
public static final String COLUMN_QUESTION = "question";
public static final String COLUMN_IMAGE = "image";
public static final String COLUMN_ANSWER1 = "answer1";
public static final String COLUMN_ANSWER2 = "answer2";
public static final String COLUMN_ANSWER3 = "answer3";
public static final String COLUMN_ANSWER4 = "answer4";
public static final String COLUMN_ANSWERNUM = "answerNum";
}
}`
資料庫 SQLiteHelper
`package com.anna.myquiz;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.view.View;
import com.anna.myquiz.DataContract.*;
import java.util.ArrayList;
import java.util.List;
public class DataDbHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "Quiz.db";
private static final int DATABASE_VERSION = 1;
private SQLiteDatabase db;
public DataDbHelper (Context context) {
super (context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate (SQLiteDatabase db) {
this.db = db;
final String SQL_CREATE_QUESTIONS_TABLE = "CREATE TABLE "
QuestionTable.TABLE_NAME " ( "
QuestionTable._ID " INTEGER PRIMARY KEY AUTOINCREMENT,"
QuestionTable.COLUMN_QUESTION " TEXT,"
QuestionTable.COLUMN_IMAGE " TEXT,"
QuestionTable.COLUMN_ANSWER1 " TEXT,"
QuestionTable.COLUMN_ANSWER2 " TEXT,"
QuestionTable.COLUMN_ANSWER3 " TEXT,"
QuestionTable.COLUMN_ANSWER4 " TEXT,"
QuestionTable.COLUMN_ANSWERNUM " INTEGER "
")";
db.execSQL(SQL_CREATE_QUESTIONS_TABLE);
fillQuestionsTable();
final String SQL_CREATE_STUDENT_TABLE = "CREATE TABLE "
StudentTable.TABLE_NAME1 " ( "
StudentTable.COLUMN_ID " INTEGER PRIMARY KEY AUTOINCREMENT,"
StudentTable.COLUMN_AM " TEXT,"
StudentTable.COLUMN_NAME " TEXT,"
StudentTable.COLUMN_SEMESTER " TEXT,"
StudentTable.COLUMN_SCORE " TEXT, "
StudentTable.COLUMN_DATE " TEXT "
")";
db.execSQL(SQL_CREATE_STUDENT_TABLE);
}
@Override
public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " QuestionTable.TABLE_NAME);
db.execSQL("DROP TABLE IF EXISTS " StudentTable.TABLE_NAME1);
onCreate(db);
}
private void fillQuestionsTable() {
Question q1 = new Question ("A is correct","arkas.jpj", "Maria" ,"anna", "Nikos" , "Andy", 1);
addQuestion (q1);
Question q2 = new Question ("B is correct","arkas1.jpg", "kjbhkjhA" ,"Bkjgkgj", "Cjvjhgj" , null, 2);
addQuestion (q2);
Question q3 = new Question ("C is correct","arkas2.jpg", "cgxcvnx" ,"xcvnxvxv", "Cgnhxfgjxf" , null, 3);
addQuestion (q3);
Question q4 = new Question ("A is correct again","NULL", "fvjxfvA" ,"Bxfgxmg", "Cxgmxmx" , null, 1);
addQuestion (q4);
Question q5 = new Question ("D is correct","NULL", "Afghf" ,"fghxggggghB", "xfgxghxghC" , "fghxghxgh", 4);
addQuestion (q5);
}
private void addQuestion(Question question){
ContentValues cv = new ContentValues();
cv.put(QuestionTable.COLUMN_QUESTION, question.getQuestion());
cv.put(QuestionTable.COLUMN_IMAGE, String.valueOf (question.getImage()));
cv.put(QuestionTable.COLUMN_ANSWER1, question.getAnswer1());
cv.put(QuestionTable.COLUMN_ANSWER2, question.getAnswer2());
cv.put(QuestionTable.COLUMN_ANSWER3, question.getAnswer3());
cv.put(QuestionTable.COLUMN_ANSWER4, question.getAnswer4());
cv.put(QuestionTable.COLUMN_ANSWERNUM, question.getAnswerNum());
db.insert(QuestionTable.TABLE_NAME, null, cv);
}
// this method is use to add new student to our sqlite database.
public void addNewStudent(String studentAm, String studentName, String studentSemester, int studentScore, String studentDate){
// on below line we are creating a variable for
// our sqlite database and calling writable method
// as we are writing data in our database.
SQLiteDatabase db = this.getWritableDatabase();
// on below line we are creating a
// variable for content values.
ContentValues values = new ContentValues();
// on below line we are passing all values
// along with its key and value pair.
values.put(StudentTable.COLUMN_AM, studentAm);
values.put(StudentTable.COLUMN_NAME, studentName);
values.put(StudentTable.COLUMN_SEMESTER, studentSemester);
values.put(StudentTable.COLUMN_SCORE, studentScore);
values.put(StudentTable.COLUMN_DATE, studentDate);
// after adding all values we are passing
// content values to our table.
db.insert(StudentTable.TABLE_NAME1, null, values);
// at last we are closing our
// database after adding database.
db.close();
}
public ArrayList<Student> readStudentInfo () {
// on below line we are creating a
// database for reading our database.
SQLiteDatabase db = this.getReadableDatabase();
// on below line we are creating a cursor with query to read data from database.
Cursor cursorCourses = db.rawQuery("SELECT * FROM " StudentTable.TABLE_NAME1, null);
// on below line we are creating a new array list.
ArrayList<Student> StudentArrayList = new ArrayList<>();
// moving our cursor to first position.
if (cursorCourses.moveToFirst()) {
do {
// on below line we are adding the data from cursor to our array list.
StudentArrayList.add(new Student(cursorCourses.getString(1),
cursorCourses.getString(5),
cursorCourses.getString(4),
cursorCourses.getString(2),
cursorCourses.getString(3)));
} while (cursorCourses.moveToNext());
// moving our cursor to next.
}
// at last closing our cursor
// and returning our array list.
cursorCourses.close();
return StudentArrayList;
}
public List<Question> getAllQuestions() {
List<Question> questionList = new ArrayList<>();
db = getReadableDatabase ();
// Choose Random Questions
Cursor c = db.rawQuery("SELECT * FROM quiz_question ORDER BY RANDOM() LIMIT 3 ",null );
if (c.moveToFirst()){
do {
Question question = new Question();
question.setQuestion(c.getString(c.getColumnIndexOrThrow(QuestionTable.COLUMN_QUESTION)));
question.setImage (c.getString(c.getColumnIndexOrThrow(QuestionTable.COLUMN_IMAGE)));
question.setAnswer1(c.getString(c.getColumnIndexOrThrow(QuestionTable.COLUMN_ANSWER1)));
question.setAnswer2(c.getString(c.getColumnIndexOrThrow(QuestionTable.COLUMN_ANSWER2)));
question.setAnswer3(c.getString(c.getColumnIndexOrThrow(QuestionTable.COLUMN_ANSWER3)));
question.setAnswer4(c.getString(c.getColumnIndexOrThrow(QuestionTable.COLUMN_ANSWER4)));
question.setAnswerNum (c.getInt(c.getColumnIndexOrThrow(QuestionTable.COLUMN_ANSWERNUM)));
questionList.add (question);
} while (c.moveToNext());
}
c.close ();
return questionList;
}
public void addScore(int StudentScore){
ContentValues cv = new ContentValues();
cv.put(DataContract.StudentTable.COLUMN_SCORE, StudentScore);
db.update(DataContract.StudentTable.TABLE_NAME1, cv, DataContract.StudentTable.COLUMN_SCORE "= ?", new String[] {"?"});
db.close();
}`
問題
`package com.anna.myquiz;
import android.graphics.drawable.Drawable;
public class Question {
private String question;
private String image;
private String answer1;
private String answer2;
private String answer3;
private String answer4;
private int answerNum;
public Question() {}
public Question (String question,String image, String answer1, String answer2, String answer3, String answer4, int answerNum) {
this.question = question;
this.image = image;
this.answer1 = answer1;
this.answer2 = answer2;
this.answer3 = answer3;
this.answer4 = answer4;
this.answerNum = answerNum;
}
public String getQuestion () {
return question;
}
public void setQuestion (String question) {
this.question = question;
}
public Object getImage () {
return Drawable.createFromPath (image);
}
public void setImage (String image) {
this.image = image;
}
public String getAnswer1 () {
return answer1;
}
public void setAnswer1 (String answer1) {
this.answer1 = answer1;
}
public String getAnswer2 () {
return answer2;
}
public void setAnswer2 (String answer2) {
this.answer2 = answer2;
}
public String getAnswer3 () {
return answer3;
}
public void setAnswer3 (String answer3) {
this.answer3 = answer3;
}
public String getAnswer4 () {
return answer4;
}
public void setAnswer4 (String answer4) {
this.answer4 = answer4;
}
public int getAnswerNum () {
return answerNum;
}
public void setAnswerNum (int answerNum) {
this.answerNum = answerNum;
}
}`
學生資訊
`package com.anna.myquiz;
public class Student {
private String studentAm;
private String studentName;
private String studentSemester;
private static int studentScore;
private String studentDate;
private int id;
public Student(){}
public Student (String studentAm, String studentName, String studentSemester, int studentScore, String studentDate, int id) {
this.studentAm = studentAm;
this.studentName = studentName;
this.studentSemester = studentSemester;
this.studentScore = studentScore;
this.studentDate = studentDate;
this.id = id;
}
public Student (String studentAm, String studentName, String studentSemester, String studentScore, String studentDate) {
}
public String getStudentAm () {
return studentAm;
}
public void setStudentAm (String studentAm) {
this.studentAm = studentAm;
}
public String getStudentName () {
return studentName;
}
public void setStudentName (String studentName) {
this.studentName = studentName;
}
public String getStudentSemester () {
return studentSemester;
}
public void setStudentSemester (String studentSemester) {this.studentSemester = studentSemester; }
public static int getStudentScore () {
return studentScore;
}
public void setStudentScore (int studentScore) {
this.studentScore = studentScore;
}
public String getStudentDate () { return studentDate; }
public void setStudentDate (String studentDate) { this.studentDate = studentDate; }
public int getId () {
return id;
}
public void setId (int id) {
this.id = id;
}
}`
測驗活動
`package com.anna.myquiz;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.content.res.ColorStateList;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.drawable.Drawable;
import android.os.CountDownTimer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Collections;
import android.graphics.Color;
import android.os.CountDownTimer;
import java.util.Collections;
import java.util.Locale;
public class QuestionsAct extends AppCompatActivity {
private TextView tvQuestion;
private TextView tvQuestionCount;
private TextView tvTime;
private TextView tvScore;
private RadioGroup radioGroup;
private RadioButton radioButton1;
private RadioButton radioButton2;
private RadioButton radioButton3;
private RadioButton radioButton4;
private Button butconfirmAns;
private Button butFinish;
private Button butForw;
private Button butBack;
private ImageView tvImgQuest;
private ColorStateList textColorDefaultRb;
private ColorStateList textColorDefaultCd;
private ArrayList<Question> questionList;
private ArrayList<Student> studentList;
private int questionCounter;
private int questionCountTotal;
private Question currentQuestion;
private int score;
private boolean answered;
private SQLiteDatabase db;
//-----------score variables---------------
public static final String EXTRA_SCORE = "extraScore";
//--------------time variables---------------------------
private static final long COUNTDOWN_IN_MILLIS = 3600000;
private CountDownTimer countDownTimer;
private long timeLeftInMillis;
@Override
protected void onCreate (Bundle savedInstanceState)
{
super.onCreate (savedInstanceState);
setContentView (R.layout.activity_questions);
tvQuestion = findViewById (R.id.tVQuestion);
tvQuestionCount = findViewById (R.id.tvQuestionCount);
tvTime = findViewById (R.id.tVTime);
tvScore = findViewById (R.id.tvScore);
radioGroup = findViewById (R.id.radioGroup);
radioButton1 = findViewById (R.id.radioButton1);
radioButton2 = findViewById (R.id.radioButton2);
radioButton3 = findViewById (R.id.radioButton3);
radioButton4 = findViewById (R.id.radioButton4);
butconfirmAns = findViewById (R.id.butConfirmAns);
butForw = findViewById (R.id.butForw);
butBack = findViewById (R.id.butBack);
tvImgQuest = findViewById (R.id.tvImgQuest);
textColorDefaultRb = radioButton1.getTextColors ();
textColorDefaultCd = tvTime.getTextColors();
DataDbHelper dbHelper = new DataDbHelper (this);
questionList = (ArrayList<Question>) bHelper.getAllQuestions ();
questionCountTotal = questionList.size ();
Collections.shuffle (questionList);
timeLeftInMillis = COUNTDOWN_IN_MILLIS;
startCountDown();
showNextQuestion ();
radioGroup.clearCheck();
butconfirmAns.setOnClickListener (new View.OnClickListener()
{
@Override
public void onClick(View v)
{
if(!answered)
{
if (radioButton1.isChecked() || radioButton2.isChecked() || radioButton3.isChecked() || radioButton4.isChecked())
{
checkAnswer();
}
else {
Toast.makeText (QuestionsAct.this, "Please select an answer", Toast.LENGTH_SHORT).show ();
}
}
else {
showNextQuestion ();
}
}
});
}
private void showNextQuestion()
{
radioButton1.setTextColor (textColorDefaultRb);
radioButton2.setTextColor (textColorDefaultRb);
radioButton3.setTextColor (textColorDefaultRb);
radioButton4.setTextColor (textColorDefaultRb);
radioGroup.clearCheck();
Question question;
if (questionCounter < questionCountTotal )
{
currentQuestion = questionList.get(questionCounter);
tvQuestion.setText(currentQuestion.getQuestion ());
tvImgQuest. setImageDrawable((Drawable) currentQuestion.getImage());
radioButton1.setText(currentQuestion.getAnswer1 ());
radioButton2.setText(currentQuestion.getAnswer2 ());
radioButton3.setText(currentQuestion.getAnswer3 ());
//radioButton4.setText(currentQuestion.getAnswer4 ());
if (DataContract.QuestionTable.COLUMN_ANSWER4.isEmpty ()){
radioButton4.setVisibility (View.INVISIBLE);
} else {
radioButton4.setText(currentQuestion.getAnswer4 ());
}
questionCounter ;
tvQuestionCount.setText("Question: " questionCounter "/" questionCountTotal);
answered = false;
butconfirmAns.setText("Submit");
}
else {
finishQuiz();
}
}
private void checkAnswer()
{
answered = true;
//countDownTimer.cancel();
RadioButton rbSelected = findViewById(radioGroup.getCheckedRadioButtonId());
int answerNum = radioGroup.indexOfChild(rbSelected) 1;
if (answerNum == currentQuestion.getAnswerNum()){
score ;
tvScore.setText("Score: " score);
}
// here must put the method to insert score in database
checkEndOfQuiz();
}
private void checkEndOfQuiz()
{
if (questionCounter < questionCountTotal)
{
butconfirmAns.setText("Next");
}
else {
butconfirmAns.setText("Finish");
//addScore(score);
}
}
private void finishQuiz()
{
Intent ResultAct = new Intent(QuestionsAct.this,ResultAct.class);
ResultAct.putExtra (EXTRA_SCORE , score);
startActivity (ResultAct);
}
private void startCountDown()
{
countDownTimer = new CountDownTimer(timeLeftInMillis, 1000)
{
@Override
public void onTick(long millisUntilFinished)
{
timeLeftInMillis = millisUntilFinished;
updateCountDownText();
}
@Override
public void onFinish()
{
timeLeftInMillis = 0;
updateCountDownText();
//checkAnswer();
}
}.start ();
}
private void updateCountDownText() {
int minutes = (int) (timeLeftInMillis / 1000) / 60;
int seconds = (int) (timeLeftInMillis / 1000) % 60;
String timeFormatted = String.format(Locale.getDefault(), "d:d", minutes, seconds);
tvTime.setText(timeFormatted);
if (timeLeftInMillis < 1000) {
tvTime.setTextColor(Color.RED);
} else {
tvTime.setTextColor(textColorDefaultCd);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
if (countDownTimer != null) {
countDownTimer.cancel();
}
}
}`
uj5u.com熱心網友回復：
考慮到隨問題發布的代碼數量有限，這是一個帶有建議技術的演示。
這利用兩個表來符合規范化方法。問題表和答案表。每個答案（子項）都有一個與單個問題（父項）的鏈接/地圖/關系/關聯。為了防止參考完整性問題，使用了外鍵約束。
首先是問題、答案和QuestionWithAnswers的一些 POJO （即它的答案）
問題POJO
class QuestionPOJO {
long questionId;
String questionText;
public QuestionPOJO(long questionId, String questionText) {
this.questionId = questionId;
this.questionText = questionText;
}
public long getQuestionId() {
return questionId;
}
public void setQuestionId(long questionId) {
this.questionId = questionId;
}
public String getQuestionText() {
return questionText;
}
public void setQuestionText(String questionText) {
this.questionText = questionText;
}
}
回答POJO
class AnswerPOJO {
long answerId;
long questionMap;
String answerText;
boolean correct = false;
public AnswerPOJO(long answerid, long questionMap, String answerText, boolean correct) {
this.answerId = answerid;
this.questionMap = questionMap;
this.answerText = answerText;
this.correct = correct;
}
public long getAnswerId() {
return answerId;
}
public void setAnswerId(long answerId) {
this.answerId = answerId;
}
public long getQuestionMap() {
return questionMap;
}
public void setQuestionMap(long questionMap) {
this.questionMap = questionMap;
}
public boolean isCorrect() {
return correct;
}
public void setCorrect(boolean correct) {
this.correct = correct;
}
public String getAnswerText() {
return answerText;
}
public void setAnswerText(String answerText) {
this.answerText = answerText;
}
}
和QuestionWithAnswerPOJO
class QuestionWithAnswersPOJO {
QuestionPOJO question;
ArrayList<AnswerPOJO> answers = new ArrayList<>();
public QuestionWithAnswersPOJO(QuestionPOJO question, List<AnswerPOJO> answers) {
this.question = question;
this.answers.clear();
this.answers.addAll(answers);
}
public QuestionPOJO getQuestion() {
return question;
}
public void setQuestion(QuestionPOJO question) {
this.question = question;
}
public ArrayList<AnswerPOJO> getAnswers() {
return answers;
}
public void setAnswers(ArrayList<AnswerPOJO> answers) {
this.answers = answers;
}
}
現在是處理所有資料庫活動的 DatabaseHelper。包括添加和獲取問題和答案的方法，尤其是獲取屬于問題的答案。
class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "questions.db";
public static final int DATABASE_VERSION = 1;
public static final String QUESTION_TABLE = "question";
public static final String QUESTION_ID_COLUMN = BaseColumns._ID;
public static final String QUESTION_TEXT_COLUMN = "question_text";
public static final String ANSWER_TABLE = "answer";
public static final String ANSWER_ID_COLUMN = BaseColumns._ID;
public static final String ANSWER_TEXT_COLUMN = "answer_text";
public static final String ANSWER_QUESTION_MAP_COLUMN = "question_map";
public static final String ANSWER_CORRECT_COLUMN = "correct";
private static volatile DatabaseHelper instance = null;
private DatabaseHelper(Context context) {
super(context,DATABASE_NAME,null,DATABASE_VERSION);
}
private static SQLiteDatabase db = null;
public static DatabaseHelper getInstance(Context context, boolean forceOpen) {
if (instance == null) {
instance = new DatabaseHelper(context);
}
if (forceOpen) {
db = instance.getWritableDatabase();
}
return instance;
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE IF NOT EXISTS " QUESTION_TABLE "("
QUESTION_ID_COLUMN " INTEGER PRIMARY KEY,"
QUESTION_TEXT_COLUMN " TEXT"
");");
db.execSQL("CREATE TABLE IF NOT EXISTS " ANSWER_TABLE "("
ANSWER_ID_COLUMN " INTEGER PRIMARY KEY,"
ANSWER_TEXT_COLUMN " TEXT,"
ANSWER_QUESTION_MAP_COLUMN " INTEGER REFERENCES " QUESTION_TABLE "(" QUESTION_ID_COLUMN ") ON DELETE CASCADE ON UPDATE CASCADE,"
ANSWER_CORRECT_COLUMN " INTEGER DEFAULT 0 /* false */"
");");
}
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
}
// Fully comprehensive Question insert
public long insertQuestion(Long questionId, String questionText) {
init_db_AsWriteableDatabase();
long rv = -2;
ContentValues cv = new ContentValues();
if (questionId != null && questionId > 0) {
cv.put(QUESTION_ID_COLUMN,questionId);
}
if (questionText != null && questionText.length() > 0) {
cv.put(QUESTION_TEXT_COLUMN,questionText);
}
if (cv.size() > 0) {
rv = db.insert(QUESTION_TABLE,null,cv);
}
return rv;
}
// Concise Question insert
public long insertQuestion(String questionText) {
return insertQuestion(null,questionText);
}
// Fully comprehensive Answer insert
public long insertAnswer(Long answerId, long questionMap, String answerText, boolean correct) {
init_db_AsWriteableDatabase();
long rv = -2;
ContentValues cv = new ContentValues();
if (answerId != null && answerId > 0) {
cv.put(ANSWER_ID_COLUMN,answerId);
}
if (answerText != null && answerText.length() > 0) {
cv.put(ANSWER_CORRECT_COLUMN,correct);
cv.put(ANSWER_TEXT_COLUMN,answerText);
cv.put(ANSWER_QUESTION_MAP_COLUMN,questionMap);
rv = db.insert(ANSWER_TABLE,null,cv);
}
return rv;
}
// long concise Answer insert
public long insertAnswer(long questionMap, String answerText, boolean correct) {
return insertAnswer(null,questionMap,answerText,correct);
}
public long insertAnswer(long questionMap, String answerText) {
return insertAnswer(questionMap,answerText,false);
}
// short concise Answer insert
private void init_db_AsWriteableDatabase() {
if (db == null) {
db = this.getWritableDatabase();
}
}
@SuppressLint("Range")
public QuestionPOJO getQuestionById(long questionId) {
QuestionPOJO rv = null;
init_db_AsWriteableDatabase();
Cursor csr = db.query(QUESTION_TABLE,null,QUESTION_ID_COLUMN "=?",new String[]{String.valueOf(questionId)},null,null,null);
if (csr.moveToNext()) {
rv = new QuestionPOJO(csr.getLong(csr.getColumnIndex(QUESTION_ID_COLUMN)),csr.getString(csr.getColumnIndex(QUESTION_TEXT_COLUMN)));
}
csr.close();
return rv;
}
@SuppressLint("Range")
public List<AnswerPOJO> getAnswersForQuestion(long questionId, boolean onlyCorrect) {
init_db_AsWriteableDatabase();
ArrayList<AnswerPOJO> rv = new ArrayList<>();
StringBuilder whereClause = new StringBuilder();
whereClause.append(ANSWER_QUESTION_MAP_COLUMN "=?");
if (onlyCorrect) {
whereClause.append(" AND ").append(ANSWER_CORRECT_COLUMN);
}
Cursor csr = db.query(ANSWER_TABLE,null,whereClause.toString(),new String[]{String.valueOf(questionId)},null,null,null);
while (csr.moveToNext()) {
rv.add(
new AnswerPOJO(
csr.getLong(csr.getColumnIndex(ANSWER_ID_COLUMN)),
questionId,
csr.getString(csr.getColumnIndex(ANSWER_TEXT_COLUMN)),
csr.getInt(csr.getColumnIndex(ANSWER_CORRECT_COLUMN)) > 0
)
);
}
csr.close();
return rv;
}
}
最后將它們放在一起，活動具有 4 個單選按鈕的布局以及作為 TextView 的相關答案。
所以布局是： -
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!">
</TextView>
<RadioGroup
android:id="@ id/question_radiogroup"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<RadioButton
android:id="@ id/answer1_radioButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:ignore="DuplicateSpeakableTextCheck"></RadioButton>
<TextView
android:id="@ id/answer1_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</TextView>
<RadioButton
android:id="@ id/answer2_radioButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</RadioButton>
<TextView
android:id="@ id/answer2_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</TextView>
<RadioButton
android:id="@ id/answer3_radioButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</RadioButton>
<TextView
android:id="@ id/answer3_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</TextView>
<RadioButton
android:id="@ id/answer4_radioButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</RadioButton>
<TextView
android:id="@ id/answer4_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</TextView>
</RadioGroup>
</LinearLayout>
- 簡單到足以顯示如何根據答案的數量隱藏按鈕（或根據按鈕/文本視圖的數量限制）
以及要展示的活動：-
public class MainActivity extends AppCompatActivity {
DatabaseHelper dbHelper;
RadioButton[] radiobuttons = new RadioButton[4];
TextView[] answerTexts = new TextView[4];
QuestionWithAnswersPOJO currentQuestionWithAnswers;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/*
prepare Radion Buttons and associated TextViews
*/
radiobuttons[0] = this.findViewById(R.id.answer1_radioButton);
radiobuttons[1] = this.findViewById(R.id.answer2_radioButton);
radiobuttons[2] = this.findViewById(R.id.answer3_radioButton);
radiobuttons[3] = this.findViewById(R.id.answer4_radioButton);
answerTexts[0] = this.findViewById(R.id.answer1_textview);
answerTexts[1] = this.findViewById(R.id.answer2_textview);
answerTexts[2] = this.findViewById(R.id.answer3_textview);
answerTexts[3] = this.findViewById(R.id.answer4_textview);
/*
Prepare to use Database
*/
dbHelper = DatabaseHelper.getInstance(this,true);
SQLiteDatabase db = dbHelper.getWritableDatabase();
/* Clear any existing data for consistent results */
db.delete(DatabaseHelper.ANSWER_TABLE,null,null);
db.delete(DatabaseHelper.QUESTION_TABLE,null,null);
/* Add some demo data 1 question with 5 answers (comment out to reduce number of answers)*/
long q1id = dbHelper.insertQuestion("What is 1 1");
dbHelper.insertAnswer(q1id,"It is 1");
dbHelper.insertAnswer(q1id,"it is 2", true);
dbHelper.insertAnswer(q1id,"It is 3");
dbHelper.insertAnswer(q1id,"It is 4");
dbHelper.insertAnswer(q1id,"It is something Else"); // will be ignored because only 4 radio buttons
/* Get the question with the answers, however many ot has */
currentQuestionWithAnswers = new QuestionWithAnswersPOJO(dbHelper.getQuestionById(q1id),dbHelper.getAnswersForQuestion(q1id,false));
/* setup (refresh) the radio buttons and textviews */
getAndSetRadioButtons(currentQuestionWithAnswers);
}
/*
Does as it says
*/
private void getAndSetRadioButtons(QuestionWithAnswersPOJO qwa) {
// Clear All
for (int i=0;i < radiobuttons.length; i ) {
radiobuttons[i].setVisibility(View.GONE);
answerTexts[i].setText("");
answerTexts[i].setVisibility(View.GONE);
}
/* show only the least of answers/radio buttons */
int numberToShow = radiobuttons.length;
if (qwa.answers.size() < radiobuttons.length) {
numberToShow = qwa.answers.size();
}
int i = 0;
for(AnswerPOJO a: qwa.answers) {
if (i < numberToShow) {
radiobuttons[i].setVisibility(View.VISIBLE);
answerTexts[i].setVisibility(View.VISIBLE);
answerTexts[i ].setText(a.answerText);
} else {
/* nothing more to do so early break out of the loop */
break;
}
}
}
}
結果
結果 1 - 運行 5 個答案（請參閱第 5 個答案的評論）
結果 2 - 所有欄 1 答案注釋掉，所以問題只有 1 個答案
使用的代碼：-
long q1id = dbHelper.insertQuestion("What is 1 1");
dbHelper.insertAnswer(q1id,"It is 1");
//dbHelper.insertAnswer(q1id,"it is 2", true);
//dbHelper.insertAnswer(q1id,"It is 3");
//dbHelper.insertAnswer(q1id,"It is 4");
//dbHelper.insertAnswer(q1id,"It is something Else"); // will be ignored because only 4 radio buttons
顯示幕 ：-
結果 3 - 僅插入第一個和第 5 個答案
等等。
發布代碼后的附加資訊。
現在添加了作為代碼的附加答案。
你說：-
嘗試使用：
if (DataContract.QuestionTable.COLUMN_ANSWER4.isEmpty ()){ radioButton4.setVisibility (View.INVISIBLE); }但似乎不起作用。
如果DataContract.QuestionTable.COLUMN_ANSWER4為空，則將面臨更嚴重的問題，因為它是列名。
對于正在檢查的問題，您應該檢查從 DB 檢索并放入currentQuestion的列的內容。
我相信使用（舊代碼注釋掉）： -
radioButton1.setText(currentQuestion.getAnswer1 ());
radioButton2.setText(currentQuestion.getAnswer2 ());
radioButton3.setText(currentQuestion.getAnswer3 ());
radioButton4.setText(currentQuestion.getAnswer4 ());
if(currentQuestion.getAnswer4() == null || currentQuestion.getAnswer4().isEmpty()) {
radioButton4.setVisibility(View.INVISIBLE);
} else {
radioButton4.setVisibility(View.VISIBLE); // just in case it is INVISIBLE
radioButton4.setText(currentQuestion.getAnswer4());
}
/*
if (DataContract.QuestionTable.COLUMN_ANSWER4.isEmpty ()){
radioButton4.setVisibility (View.INVISIBLE);
} else {
radioButton4.setText(currentQuestion.getAnswer4 ());
}
*/
將解決這個問題。例如在第三季度：-
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