我在AndroidStudio上使用Kotlin为一个大学项目创建了一个数据库应用程序。 我正在尝试使用SQLite创建数据库。 下面是我为启动数据库而创建的DBHelper kt文件。 当我调用其中一个函数来创建数据库时，应用程序崩溃。 当我在SQL Cypher中从数据库中检查。db文件时，这些表不会出现。 这些错误的描述性不够，我无法找出如何修复它。 谢谢你的帮助。
package com.example.guviolinapp
import android.content.ContentValues
import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
class DBHelper(context: Context) : SQLiteOpenHelper(context, DATABASE_NAME, null, 1) {
companion object{
//Companion object that holds the name of everything in the database
private val DATABASE_NAME = "violininfo.db"
private val GAME_TABLE = "game_table"
private val COL_GAME_NUMBER = "game_number"
private val COL_GAME_SCORE = "game_score"
private val SCORE_TABLE = "score_table"
private val COL_SCORE_LEVEL = "quiz_level"
private val COL_QUIZ_SCORE = "quiz_score"
private val QUESTION_TABLE = "questions_table"
private val COL_QUIZ_LEVEL = "quiz_level"
private val COL_QUESTION_NUM = "question_number"
private val COL_QUIZ_QUESTION = "quiz_questions"
private val COL_IMAGE_PATH = "quiz_image_path"
private val COL_QUIZ_OPTION_ONE = "quiz_options_one"
private val COL_QUIZ_OPTION_TWO = "quiz_options_two"
private val COL_QUIZ_OPTION_THREE = "quiz_options_three"
private val COL_QUIZ_OPTION_FOUR = "quiz_options_four"
private val COL_QUIZ_ANSWER = "quiz_answer"
}
//On create of the Application creating the actual database in the device
override fun onCreate(db: SQLiteDatabase) {
//Variable that holds the SQL query to create the table
val CREATE_GAME_TABLE =
"CREATE TABLE IF NOT EXISTS $GAME_TABLE" +
"($COL_GAME_NUMBER INTEGER PRIMARY KEY AUTOINCREMENT, " +
"$COL_GAME_SCORE INTEGER" +
")"
//Variable that holds the SQL query to create the table
val CREATE_QUESTION_TABLE =
"CREATE TABLE $QUESTION_TABLE" +
"($COL_QUIZ_LEVEL INTEGER, " +
"$COL_QUESTION_NUM INTEGER, " +
"$COL_QUIZ_QUESTION TEXT, " +
"$COL_IMAGE_PATH TEXT, " +
"$COL_QUIZ_OPTION_ONE TEXT, " +
"$COL_QUIZ_OPTION_TWO TEXT , " +
"$COL_QUIZ_OPTION_THREE TEXT, " +
"$COL_QUIZ_OPTION_FOUR TEXT, " +
"$COL_QUIZ_ANSWER INTEGER" +
"PRIMARY KEY ($COL_QUIZ_LEVEL, $COL_QUESTION_NUM)" +
")"
//Variable that holds the SQL query to create the table
val CREATE_SCORE_TABLE =
"CREATE TABLE $SCORE_TABLE" +
"($COL_SCORE_LEVEL INTEGER PRIMARY KEY, " +
"$COL_QUIZ_SCORE INTEGER" +
"FOREIGN KEY $COL_SCORE_LEVEL REFERENCES $QUESTION_TABLE($COL_QUIZ_LEVEL) ON DELETE CASCADE" +
")"
//Functions that execute the sql script. The first one prevents null in the db
db.execSQL("CREATE TABLE $QUESTION_TABLE($COL_QUIZ_LEVEL INTEGER, $COL_QUESTION_NUM INTEGER, $COL_QUIZ_QUESTION TEXT, $COL_IMAGE_PATH TEXT, $COL_QUIZ_OPTION_ONE TEXT, $COL_QUIZ_OPTION_TWO TEXT , $COL_QUIZ_OPTION_THREE TEXT, $COL_QUIZ_OPTION_FOUR TEXT, $COL_QUIZ_ANSWER INTEGER, PRIMARY KEY ($COL_QUIZ_LEVEL, $COL_QUESTION_NUM))")
db.execSQL("CREATE TABLE $GAME_TABLE($COL_GAME_NUMBER INTEGER PRIMARY KEY AUTOINCREMENT, $COL_GAME_SCORE INTEGER)")
db.execSQL("CREATE TABLE $SCORE_TABLE($COL_SCORE_LEVEL INTEGER PRIMARY KEY, $COL_QUIZ_SCORE INTEGER, FOREIGN KEY ($COL_SCORE_LEVEL) REFERENCES $QUESTION_TABLE($COL_QUIZ_LEVEL) ON DELETE CASCADE)")
fillQuestionsTable()
}
//Function that drops the database and remakes it for when the database is updated. It can be done two ways.
//The app can be deleted, or the version can be increased
override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
val DROP_SCORE_TABLE = "DROP TABLE IF EXISTS $SCORE_TABLE"
val DROP_GAME_TABLE = "DROP TABLE IF EXISTS $GAME_TABLE"
val DROP_QUESTION_TABLE = "DROP TABLE IF EXISTS $QUESTION_TABLE"
db.execSQL(DROP_SCORE_TABLE)
db.execSQL(DROP_GAME_TABLE)
db.execSQL(DROP_QUESTION_TABLE)
onCreate(db)
}
override fun onConfigure(db: SQLiteDatabase) {
super.onConfigure(db)
db.setForeignKeyConstraintsEnabled(true)
}
//Function to insert values into the Score table
fun insertScoreTable(quizLevel: Int, quizScore: Int): Boolean? {
//Creates the writable database that can be accessed
val db = this.writableDatabase
//Function to insert values that will be inserted into the database
val cv = ContentValues()
//Inserting the values with a specific identifier in which the value needs to be inserted
cv.put(COL_SCORE_LEVEL, quizLevel)
cv.put(COL_QUIZ_SCORE, quizScore)
//Executing the actual insert database
val res = db.insert(SCORE_TABLE, null, cv)
return !res.equals(-1)
}
//Function to insert values into the Game table
fun insertGameTable(gameNum: Int, gameScore: Int): Boolean? {
//Creates the writable database that can be accessed
val db = this.writableDatabase
//Function to insert values that will be inserted into the database
val cv = ContentValues()
//Inserting the values with a specific identifier in which the value needs to be inserted
cv.put(COL_GAME_NUMBER, gameNum)
cv.put(COL_GAME_SCORE, gameScore)
//Executing the actual insert database
val res = db.insert(GAME_TABLE, null, cv)
return !res.equals(-1)
}
//Function to insert values into the Questions table
private fun insertQuestionsTable(questionTable: QuestionsTable) {
//Creates the writable database that can be accessed
val db = this.writableDatabase
//Function to insert values that will be inserted into the database
val cv = ContentValues()
//Inserting the values with a specific identifier in which the value needs to be inserted
cv.put(COL_QUIZ_LEVEL, questionTable.quiz_level)
cv.put(COL_QUESTION_NUM, questionTable.question_number)
cv.put(COL_QUIZ_QUESTION, questionTable.quiz_questions)
cv.put(COL_IMAGE_PATH, questionTable.quiz_image_path)
cv.put(COL_QUIZ_OPTION_ONE, questionTable.quiz_option_one)
cv.put(COL_QUIZ_OPTION_TWO, questionTable.quiz_option_two)
cv.put(COL_QUIZ_OPTION_THREE, questionTable.quiz_option_three)
cv.put(COL_QUIZ_OPTION_FOUR, questionTable.quiz_option_four)
cv.put(COL_QUIZ_ANSWER, questionTable.quiz_answer)
//Executing the actual insert database
val res = db.insert(QUESTION_TABLE, null, cv)
//return !res.equals(-1)
}
//Function to insert all the questions into the database
private fun fillQuestionsTable() {
//Variable with the data class holding the values for each question
val l1q1 = QuestionsTable(1, 1, "What note is this?",
"@drawable/questionImage/l1q1", "Minim",
"Semibreve", "Crochet", "Quaver", 4)
//Calling the insertQuestionsTable to insert the question
insertQuestionsTable(l1q1)
val l1q2 = QuestionsTable(1, 2, "What note is this?",
"@drawable/questionImage/l1q2", "Quaver",
"Minim", "Crochet", "Semibreve", 3)
insertQuestionsTable(l1q2)
val l1q3 = QuestionsTable(1, 3, "What rest is this?",
"@drawable/questionImage/l1q3", "Whole",
"Eighth", "Half", "Quarter", 2)
insertQuestionsTable(l1q3)
val l1q4 = QuestionsTable(1, 4, "What rest is this?",
"@drawable/questionImage/l1q4", "Quarter",
"Eighth", "Whole", "Half", 1)
insertQuestionsTable(l1q4)
val l1q5 = QuestionsTable(1, 5, "What rest is this?",
"@drawable/questionImage/l1q5", "Whole",
"Eighth", "Quarter", "Half", 1)
insertQuestionsTable(l1q5)
val l1q6 = QuestionsTable(1, 6, "What rest is this?",
"@drawable/questionImage/l1q6", "Quarter",
"Eighth", "Whole", "Half", 4)
insertQuestionsTable(l1q6)
val l1q7 = QuestionsTable(1, 7, "What note is this?",
"@drawable/questionImage/l1q7", "Minim",
"Quaver", "Semibreve", "Crochet", 1)
insertQuestionsTable(l1q7)
val l1q8 = QuestionsTable(1, 8, "What note is this?",
"@drawable/questionImage/l1q8", "Quaver",
"Semibreve", "Crochet", "Minim", 2)
insertQuestionsTable(l1q8)
val l1q9 = QuestionsTable(1, 9, "How many beats in this rest?",
"@drawable/questionImage/l1q9", "Half Beat",
"One Beat", "Two Beats", "Four Beats", 3)
insertQuestionsTable(l1q9)
val l1q10 = QuestionsTable(1, 10, "How many beats in this rest?",
"@drawable/questionImage/l1q10", "Four Beats",
"One Beat", "Two Beats", "Half Beat", 4)
insertQuestionsTable(l1q10)
val l1q11 = QuestionsTable(1, 11, "How many beats in this rest?",
"@drawable/questionImage/l1q11", "One Beat",
"Half Beat", "Two Beats", "Four Beats", 4)
insertQuestionsTable(l1q11)
val l1q12 = QuestionsTable(1, 12, "How many beats in this note?",
"@drawable/questionImage/l1q12", "Four Beats",
"One Beat", "Half Beat", "Two Beats", 2)
insertQuestionsTable(l1q12)
val l1q13 = QuestionsTable(1, 13, "How many beats in this rest?",
"@drawable/questionImage/l1q13", "Two Beats",
"One Beat", "Four Beats", "Half Beat", 2)
insertQuestionsTable(l1q13)
val l1q14 = QuestionsTable(1, 14, "How many beats in this note?",
"@drawable/questionImage/l1q14", "Two Beats",
"Half Beat", "Four Beats", "One Beat", 3)
insertQuestionsTable(l1q14)
val l1q15 = QuestionsTable(1, 15, "How many beats in this note?",
"@drawable/questionImage/l1q15", "One Beat",
"Four Beats", "Half Beat", "Two Beats", 3)
insertQuestionsTable(l1q15)
val l2q1 = QuestionsTable(2, 1, "What string is this?",
"@drawable/questionImage/l2q1", "D",
"A", "G", "E", 1)
insertQuestionsTable(l2q1)
val l2q2 = QuestionsTable(2, 2, "What note is this?",
"@drawable/questionImage/l2q2", "F sharp",
"E", "G sharp", "A", 1)
insertQuestionsTable(l2q2)
val l2q3 = QuestionsTable(2, 3, "What note is this?",
"@drawable/questionImage/l2q3", "G",
"B", "A", "C", 2)
insertQuestionsTable(l2q3)
val l2q4 = QuestionsTable(2, 4, "What note is this?",
"@drawable/questionImage/l2q4", "E",
"F sharp", "A", "G sharp", 4)
insertQuestionsTable(l2q4)
val l2q5 = QuestionsTable(2, 5, "What note is this?",
"@drawable/questionImage/l2q5", "G",
"A", "B", "C", 4)
insertQuestionsTable(l2q5)
val l2q6 = QuestionsTable(2, 6, "What string is this?",
"@drawable/questionImage/l2q6", "A",
"D", "E", "G", 3)
insertQuestionsTable(l2q6)
val l2q7 = QuestionsTable(2, 7, "What note is this?",
"@drawable/questionImage/l2q7", "B",
"A", "C", "G", 2)
insertQuestionsTable(l2q7)
val l2q8 = QuestionsTable(2, 8, "What note is this?",
"@drawable/questionImage/l2q8", "E",
"D", "G", "F sharp", 4)
insertQuestionsTable(l2q8)
val l2q9 = QuestionsTable(2, 9, "What note is this?",
"@drawable/questionImage/l2q9", "A",
"B", "C sharp", "D", 4)
insertQuestionsTable(l2q9)
val l2q10 = QuestionsTable(2, 10, "What note is this?",
"@drawable/questionImage/l2q10", "F sharp",
"D", "E", "G", 3)
insertQuestionsTable(l2q10)
val l2q11 = QuestionsTable(2, 11, "What note is this?",
"@drawable/questionImage/l2q11", "A",
"B", "C sharp", "D", 2)
insertQuestionsTable(l2q11)
val l2q12 = QuestionsTable(2, 12, "What string is this?",
"@drawable/questionImage/l2q12", "D",
"G", "E", "A", 4)
insertQuestionsTable(l2q12)
val l2q13 = QuestionsTable(2, 13, "What note is this?",
"@drawable/questionImage/l2q13", "C sharp",
"D", "B", "A", 1)
insertQuestionsTable(l2q13)
val l2q14 = QuestionsTable(2, 14, "What note is this?",
"@drawable/questionImage/l2q14", "E",
"G", "F sharp", "D", 2)
insertQuestionsTable(l2q14)
val l2q15 = QuestionsTable(2, 15, "What string is this?",
"@drawable/questionImage/l2q15", "A",
"D", "G", "E", 3)
insertQuestionsTable(l2q15)
val l3q1 = QuestionsTable(3, 1, "What is this called?",
"@drawable/questionImage/l3q1", "Treble Clef",
"Tie", "Stave", "Flat", 3)
insertQuestionsTable(l3q1)
val l3q2 = QuestionsTable(3, 2, "What is this called?",
"@drawable/questionImage/l3q2", "Stave",
"Bass Clef", "Sharp", "Treble Clef", 3)
insertQuestionsTable(l3q2)
val l3q3 = QuestionsTable(3, 3, "What is this called?",
"@drawable/questionImage/l3q3", "Bar",
"Stave", "Sharp", "Bass Clef", 1)
insertQuestionsTable(l3q3)
val l3q4 = QuestionsTable(3, 4, "What is this called?",
"@drawable/questionImage/l3q4", "Time Signature",
"Treble Clef", "Natural", "Bass Clef", 2)
insertQuestionsTable(l3q4)
val l3q5 = QuestionsTable(3, 5, "What is this called?",
"@drawable/questionImage/l3q5", "Bar",
"Key Signature", "Sharp", "Tie", 2)
insertQuestionsTable(l3q5)
val l3q6 = QuestionsTable(3, 6, "What is this called?",
"@drawable/questionImage/l3q6", "Treble Clef",
"Key Signature", "Bar", "Tie", 4)
insertQuestionsTable(l3q6)
val l3q7 = QuestionsTable(3, 7, "What is this called?",
"@drawable/questionImage/l3q7", "Flat",
"Sharp", "Bar", "Natural", 1)
insertQuestionsTable(l3q7)
val l3q8 = QuestionsTable(3, 8, "What is this called?",
"@drawable/questionImage/l3q8", "Treble Clef",
"Flat", "Sharp", "Bass Clef", 4)
insertQuestionsTable(l3q8)
val l3q9 = QuestionsTable(3, 9, "What is this called?",
"@drawable/questionImage/l3q9", "Sharp",
"Time Signature", "Flat", "Tie", 2)
insertQuestionsTable(l3q9)
val l3q10 = QuestionsTable(3, 10, "What is this called?",
"@drawable/questionImage/l3q10", "Bass Clef",
"Bar", "Natural", "Sharp", 3)
insertQuestionsTable(l3q10)
val l3q11 = QuestionsTable(3, 11, "What is this called?",
"@drawable/questionImage/l3q11", "Decrescendo",
"Accent", "Forte", "Crescendo", 1)
insertQuestionsTable(l3q11)
val l3q12 = QuestionsTable(3, 12, "What is this called?",
"@drawable/questionImage/l3q12", "Decrescendo",
"Forte", "Accent", "Piano", 4)
insertQuestionsTable(l3q12)
val l3q13 = QuestionsTable(3, 13, "What is this called?",
"@drawable/questionImage/l3q13", "Forte",
"Accent", "Crescendo", "Decrescendo", 1)
insertQuestionsTable(l3q13)
val l3q14 = QuestionsTable(3, 14, "What is this called?",
"@drawable/questionImage/l3q14", "Decrescendo",
"Accent", "Crescendo", "Forte", 2)
insertQuestionsTable(l3q14)
val l3q15 = QuestionsTable(3, 15, "What is this called?",
"@drawable/questionImage/l3q15", "Forte",
"Piano", "Accent", "Crescendo", 4)
insertQuestionsTable(l3q15)
}
//Function get the questions back from the database.
fun getAllQuestions(): ArrayList<QuestionsTable> {
//Creating the ArrayList that holds the questions retrieved from the database
val rv = ArrayList<QuestionsTable>()
val db = this.writableDatabase
//Query that gets the values from the database
val csr = db.query(QUESTION_TABLE,null /* ALL columns */,null,null,null,null,null)
//While loop that insert the values into the array list while there is a next value
while (csr.moveToNext()) {
//Adding values to the array list
rv.add(
//Inserting the values into the data class
QuestionsTable(
//Getting the actual values from the query
csr.getInt(csr.getColumnIndex(COL_QUIZ_LEVEL)),
csr.getInt(csr.getColumnIndex(COL_QUESTION_NUM)),
csr.getString(csr.getColumnIndex(COL_QUIZ_QUESTION)),
csr.getString(csr.getColumnIndex(COL_IMAGE_PATH)),
csr.getString(csr.getColumnIndex(COL_QUIZ_OPTION_ONE)),
csr.getString(csr.getColumnIndex(COL_QUIZ_OPTION_TWO)),
csr.getString(csr.getColumnIndex(COL_QUIZ_OPTION_THREE)),
csr.getString(csr.getColumnIndex(COL_QUIZ_OPTION_FOUR)),
csr.getInt(csr.getColumnIndex(COL_QUIZ_ANSWER))
)
)
}
//Closing the database query
csr.close()
//Returning the ArrayList
return rv
}
//Function get the scores back from the database.
fun getAllScores(): ArrayList<ScoreTable> {
//Creating the ArrayList that holds the questions retrieved from the database
val rv = ArrayList<ScoreTable>()
val db = this.writableDatabase
//While loop that insert the values into the array list while there is a next value
val csr = db.query(SCORE_TABLE,null /* ALL columns */,null,null,null,null,null)
//While loop that insert the values into the array list while there is a next value
while (csr.moveToNext()) {
//Adding values to the array list
rv.add(
//Inserting the values into the data class
ScoreTable(
//Getting the actual values from the query
csr.getInt(csr.getColumnIndex(COL_SCORE_LEVEL)),
csr.getInt(csr.getColumnIndex(COL_QUIZ_SCORE))
)
)
}
//Closing the database query
csr.close()
//Returning the ArrayList
return rv
}
//Function get the Game scores back from the database.
fun getAllGameScores(): ArrayList<GameTable> {
//Creating the ArrayList that holds the questions retrieved from the database
val rv = ArrayList<GameTable>()
val db = this.writableDatabase
//While loop that insert the values into the array list while there is a next value
val csr = db.query(GAME_TABLE,null /* ALL columns */,null,null,null,null,null)
//While loop that insert the values into the array list while there is a next value
while (csr.moveToNext()) {
//Adding values to the array list
rv.add(
//Inserting the values into the data class
GameTable(
//Getting the actual values from the query
csr.getInt(csr.getColumnIndex(COL_GAME_NUMBER)),
csr.getInt(csr.getColumnIndex(COL_GAME_SCORE))
)
)
}
//Closing the database query
csr.close()
//Returning the ArrayList
return rv
}
}
这是activity，我试着打印出所有值的整个ArrayList，看看数据库中是否有任何内容。
package com.example.guviolinapp
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.TextView
class QuizQuestionsActivity : AppCompatActivity() {
//Initialization of variables that will be used
lateinit var myDb: DBHelper
private var mQuizLevel: String? = null
//Setting the database variable and it's context
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_quiz_questions)
//Receiving the extra information from the Intent
mQuizLevel = intent.getStringExtra("LevelInformation")
myDb = DBHelper(this)
val questionList = myDb.getAllQuestions()
val tvOptionOne = findViewById<TextView>(R.id.tvOptionOne)
Log.d("Database Query",questionList.toString())
}
}
这是我启动activity时得到的误差。
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.guviolinapp, PID: 9893
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.guviolinapp/com.example.guviolinapp.QuizQuestionsActivity}: java.lang.IllegalStateException: getDatabase called recursively
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.IllegalStateException: getDatabase called recursively
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:203)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
at com.example.guviolinapp.DBHelper.insertQuestionsTable(DBHelper.kt:118)
at com.example.guviolinapp.DBHelper.fillQuestionsTable(DBHelper.kt:143)
at com.example.guviolinapp.DBHelper.onCreate(DBHelper.kt:65)
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:251)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
at com.example.guviolinapp.DBHelper.getAllQuestions(DBHelper.kt:372)
at com.example.guviolinapp.QuizQuestionsActivity.onCreate(QuizQuestionsActivity.kt:24)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
您将在数据库帮助器onCreate()中调用fillQuestionStable()，该填充函数最终访问WritableDatabase，这就是“Called recursyly”错误的原因。
将SqliteDatabase参数从onCreate()向下传递到填充/插入函数，并删除WritableDatabase访问。
