我正在开发字典应用程序。上次我问如何开始开发Pre-Created SQLite database integrate into android app。现在，我问如何解决该问题。问题是：我按下android studio中的开始按钮以在emulator中显示我的应用程序。应用程序进入了模拟电话，但是在与应用程序交互后（按下翻译按钮），它崩溃并在logcat中显示错误消息。我认为database中的问题，我的知识不足以解决这个问题。
视频：https://drive.google.com/file/d/1cM8ENxxZpdXCdNf4b4jbjCio-5UYT77E/view?usp=sharing
Logcat：
Process: com.example.f_a_11_8_2019,PID: 5719
android.database.sqlite.SQLiteException: no such table: WORDS (code 1 SQLITE_ERROR):,while compiling: SELECT KAZAKH FROM WORDS WHERE TURKISH = ?
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:986)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:593)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:590)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:61)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:46)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1443)
at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1290)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1161)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1329)
at com.example.f_a_11_8_2019.Mainactivity$1.onClick(Mainactivity.java:38)
at android.view.View.performClick(View.java:7125)
at android.view.View.performClickinternal(View.java:7102)
at android.view.View.access$3500(View.java:801)
at android.view.View$PerformClick.run(View.java:27336)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.activityThread.main(activityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
DatabaseHelper类：
package com.example.f_a_11_8_2019;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class DatabaseHelper extends SQLiteOpenHelper {
private static final int database_VERSION = 1;
static final String DB_PATH = "data/data/com.example.f_a_11_8_2019/databases/";
static final String DB_NAME = "Dictionary2.db";
SQLiteDatabase sqLiteDatabase;
Context context;
public DatabaseHelper(Context mContext) {
super(mContext,DB_NAME,null,database_VERSION);
mContext = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) {
}
//eger veritababi yoksa kopyalayip olustaracak,varsa hic bir sey yapmayacak
public void createDatabase() throws IOException{
boolean dbExist = checkDatabase();
if(dbExist){
//database varsa
}else {
getReadableDatabase();
//veritabani daha once olusturulmamis sa burada veritabanini kopyaliyoruzk
copyDatabase();
}
}
//veritababi daha once olusturuldu mu olusturulmamismi mi bunu ogrenecek
//olusturlmussa true olusturulmamismi false degeri dondur
public boolean checkDatabase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH+DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath,SQLiteDatabase.OPEN_READONLY);
}
catch (SQLiteException e){}
if (checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
public void copyDatabase() throws IOException{
//assets --> DB_PATH + DB_NAME;
try {
InputStream myInput = context.getassets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream myoutput = new FileOutputStream(outFileName);
byte [] buffer = new byte[1024];
int lenght;
while ((lenght = myInput.read(buffer)) > 0){
myoutput.write(buffer,lenght);
}
myoutput.flush();
myoutput.close();
myInput.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public void openDatabase() throws IOException{
String myPath = DB_PATH + DB_NAME;
sqLiteDatabase = SQLiteDatabase.openDatabase(myPath,SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if (sqLiteDatabase != null) sqLiteDatabase.close();
super.close();
}
public SQLiteDatabase getDatabase(){
return sqLiteDatabase;
}
}
Mainactivity类：
package com.example.f_a_11_8_2019;
import androidx.appcompat.app.AppCompatactivity;
import android.content.Context;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import java.io.IOException;
public class Mainactivity extends AppCompatactivity {
DatabaseHelper dbHelper;
Context context = this;
EditText tr,kz;
Button trans;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new DatabaseHelper(context);
try {
dbHelper.createDatabase();
dbHelper.openDatabase();
} catch (IOException e){
e.printStackTrace();
}
tr = (EditText) findViewById(R.id.tr);
kz = (EditText) findViewById(R.id.kz);
trans = (Button) findViewById(R.id.trans);
trans.setOnClicklistener(new View.OnClicklistener() {
@Override
public void onClick(View v) {
String turkceKelime = tr.getText().toString();
Cursor crs = dbHelper.getDatabase().query("WORDS",new String[] {"KAZAKH"},"TURKISH = ?",new String[]{turkceKelime},null);
if(crs.getcount() > 0){
crs.moveToFirst();
String ingilizceKelime = crs.getString(crs.getcolumnIndex("KAZAKH"));
kz.setText(ingilizceKelime);
}else {
Toast.makeText(context,"Kelimenin karsiligi bulunamadi",Toast.LENGTH_SHORT).show();
tr.getText().clear();
}
}
});
}
@Override
protected void onStop() {
super.onStop();
dbHelper.close();
}
}