Java SQLite DatabaseHelper类未创建数据库
嗨,我一直在开发一个简单的计时器应用程序,在数据库中存储圈数。我已经创建了一个数据库助手类。当我试图从我的活动中插入数据时,我得到一个错误,说没有创建这样的表。为了简单起见,我从这里的活动中删除了一些代码(按钮代码等) 起初,我认为使用常量有问题,但我创建的表中没有任何常量,我得到了相同的错误。Java SQLite DatabaseHelper类未创建数据库,java,android,sqlite,android-sqlite,Java,Android,Sqlite,Android Sqlite,嗨,我一直在开发一个简单的计时器应用程序,在数据库中存储圈数。我已经创建了一个数据库助手类。当我试图从我的活动中插入数据时,我得到一个错误,说没有创建这样的表。为了简单起见,我从这里的活动中删除了一些代码(按钮代码等) 起初,我认为使用常量有问题,但我创建的表中没有任何常量,我得到了相同的错误。 更新:我认为在DBHelper中从未调用过onCreate DatabaseHelper.java package com.example.andrei.gymhelp; import android
更新:我认为在DBHelper中从未调用过onCreate DatabaseHelper.java
package com.example.andrei.gymhelp;
import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String TAG = "SQLMessage";
private static final String DATABASE_NAME = "StoredResults.db";
private static final int DATABASE_VERSION = 2;
private static DatabaseHelper mDatabaseInstance = null;
private Context mContext;
public static DatabaseHelper newInstance(Context context){
//first check to see if the database helper
//member data is null
//create a new one if it is null
if (mDatabaseInstance == null){
mDatabaseInstance = new DatabaseHelper(context.getApplicationContext());
}
//either way we have to always return an instance of
//our database class each time this method is called
return mDatabaseInstance;
}
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
mContext = context;
}
private static final String CREATE_TABLE_LAPS = "create table results_table "
+ "("
+ "_id" + " integer primary key autoincrement, "
+ "timestamp" + " text not null, "
+ "laps" + " text not null, "
+ ")";
@Override
public void onCreate(SQLiteDatabase db) {
try{
db.execSQL(CREATE_TABLE_LAPS);
Log.d(TAG, "TABLE WAS CREATED ");
} catch (SQLException e) {
Log.d(TAG, " Error create database " + e.getMessage());
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + Constants.LAPS_TABLE);
onCreate(db);
}
}
TimerActivity.java
public class TimerActivity extends AppCompatActivity {
private Context context;
private TextView timer;
private Button btnStart;
private Button btnLap;
private Button btnStop;
private Button btnSave;
private TextView laps;
private int lapsCounter = 1;
private ScrollView scrollLaps;
private boolean saved = false;
private String savedLaps = "";
private static final String TAG = "MESSAGE";
Date dateAndTime = new Date();
private String sequenceTimestamp;
private DatabaseHelper mDBHelper;
private SQLiteDatabase mDatabase;
private Chronometer mainChronometer;
private Thread threadChrono;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout_timer);
mDBHelper = new DatabaseHelper(this);
mDatabase = mDBHelper.getWritableDatabase();
btnSave.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mainChronometer != null) {
Context context = getApplicationContext();
CharSequence text = getString(R.string.chrono_not_stopped);
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}else{
if (!saved) {
Log.v(TAG, "LAPS = " + savedLaps);
Log.v(TAG, String.valueOf(System.currentTimeMillis()));
saved = true;
Context context = getApplicationContext();
CharSequence text = getString(R.string.saved_toast);
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
sequenceTimestamp = (String) DateFormat.format("hh:mm:ss dd-MM-yyyy", dateAndTime.getTime());
saveResultsToDatabase(sequenceTimestamp, savedLaps);
Log.v(TAG, sequenceTimestamp);
} else {
Context context = getApplicationContext();
CharSequence text = getString(R.string.alreadysaved_toast);
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}
}
}
});
}
public void updateTimer(final String time){
runOnUiThread(new Runnable() {
@Override
public void run() {
timer.setText(time);
}
});
}
public void saveResultsToDatabase(String timestamp,String stringOfLaps) {
//if (mDatabase != null) {
//prepare the transaction information that will be saved to the database
ContentValues values = new ContentValues();
values.put(Constants.COLUMN_TIMESTAMP, timestamp);
values.put(Constants.COLUMN_LAPS, stringOfLaps);
try {
Log.i(TAG,"SAVE RESULTS WAS CALLED");
mDatabase.insert(Constants.LAPS_TABLE, null, values);
mDatabase.close();
}catch (SQLException e){
Log.d(TAG,e.getMessage());
}
//}
}
}
错误
01-08 22:09:09.081 10656-10656/com.example.andrei.gymhelp E/SQLiteLog: (1)
01-08 22:09:09.083 10656-10656/com.example.andrei.gymhelp E/SQLiteDatabase: Error inserting timestamp=10:09:04 08-01-2018 laps=Lap 1:
00:00:00:786|Lap 2: 00:00:01:283|Lap 3: 00:00:01:756|Lap 5: 00:00:02:177|
android.database.sqlite.SQLiteException: no such table: results_table (Sqlite code 1): , while compiling: INSERT INTO results_table(timestamp,laps) VALUES (?,?), (OS error - 2:No such file or directory)
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:910)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:521)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:603)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:63)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1725)
at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1593)
at com.example.andrei.gymhelp.TimerActivity.saveResultsToDatabase(TimerActivity.java:186)
at com.example.andrei.gymhelp.TimerActivity$4.onClick(TimerActivity.java:150)
at android.view.View.performClick(View.java:5646)
at android.view.View$PerformClick.run(View.java:22459)
at android.os.Handler.handleCallback(Handler.java:761)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:156)
at android.app.ActivityThread.main(ActivityThread.java:6523)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:942)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:832)
01-08 22:09:09.081 10656-10656/com.example.andrei.gymhelp E/SQLiteLog:(1)
01-08 22:09:09.083 10656-10656/com.example.andrei.gymhelp E/SQLiteDatabase:插入时间戳时出错=10:09:04 08-01-2018圈数=第1圈:
00:00:00:786 |第2圈:00:00:01:283 |第3圈:00:00:01:756 |第5圈:00:00:02:177|
android.database.sqlite.SQLiteException:没有这样的表:results_table(sqlite代码1):,编译时:插入results_table(timestamp,laps)值(?,),(操作系统错误-2:没有这样的文件或目录)
位于android.database.sqlite.SQLiteConnection.nativePrepareStatement(本机方法)
位于android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:910)
位于android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:521)
位于android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:603)
位于android.database.sqlite.SQLiteProgram.(SQLiteProgram.java:63)
位于android.database.sqlite.SQLiteStatement.(SQLiteStatement.java:31)
位于android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1725)
位于android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1593)
位于com.example.andrei.gymhelp.TimerActivity.saveResultsToDatabase(TimerActivity.java:186)
在com.example.andrei.gymhelp.TimerActivity$4.onClick(TimerActivity.java:150)
在android.view.view.performClick上(view.java:5646)
在android.view.view$PerformClick.run(view.java:22459)
位于android.os.Handler.handleCallback(Handler.java:761)
位于android.os.Handler.dispatchMessage(Handler.java:98)
位于android.os.Looper.loop(Looper.java:156)
位于android.app.ActivityThread.main(ActivityThread.java:6523)
位于java.lang.reflect.Method.invoke(本机方法)
在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:942)上
位于com.android.internal.os.ZygoteInit.main(ZygoteInit.java:832)
数据库确实存在。但是,数据库中不存在表结果\u表
由于语法错误,未创建该表。最后定义的laps列后面有一个逗号,因此需要另一个列定义
若要修复此更改,请将+“laps”+“text not null”
更改为+“laps”+“text not null”
(即删除末尾的逗号)
只有当数据库不存在时才会调用
onCreate
方法,在重新运行应用程序之前,您应该a)删除应用程序的数据或b)卸载应用程序。我建议您不要在数据库帮助器类中捕获SQLException。这将帮助您立即在代码中找到语法错误。如果您想管理不可预见的错误并向用户显示适当的消息,则在UI代码中使用try…catch语句更合适。我会记住这一点,干杯!谢谢,3小时后我也发现了错误:(