Android Studio-无法创建SQL数据库/表-应用无法打开

Question

Working on creating a SQL database in Android Studio, however, the app won't open on the emulator and no database file is found at /data/data/package/databases/ when using the device monitor.

I'm working on api_21 emulator which I believe should support sqlite. Eventually I'll be using the database information to perform various function with the buttons, but as of right now, those are ignored.

please help!

MainActivity.java

package edu.tamu.thecaddyapp;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

Button buttonDriver, buttonFouriron, buttonFiveiron, buttonSixiron, buttonSeveniron, buttonEightiron, buttonNineiron, buttonPW, buttonFiftysix, buttonSW, buttonSixty;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    SQLiteHelper db = new SQLiteHelper(this);
    db.getWritableDatabase();

    buttonDriver = findViewById(R.id.button_DRIVER);
    buttonFouriron = findViewById(R.id.button_4IRON);
    buttonFiveiron = findViewById(R.id.button_5IRON);
    buttonSixiron = findViewById(R.id.button_6IRON);
    buttonSeveniron = findViewById(R.id.button_7IRON);
    buttonEightiron = findViewById(R.id.button_8IRON);
    buttonNineiron = findViewById(R.id.button_9IRON);
    buttonPW = findViewById(R.id.button_PW);
    buttonSW = findViewById(R.id.button_SW);
    buttonFiftysix = findViewById(R.id.button_56DEG);
    buttonSixty = findViewById(R.id.button_60DEG);

}

public void buttonDriver(View view) {
}

public void buttonFouriron(View view) {
}

public void buttonFiveiron(View view) {
}

public void buttonSixiron(View view) {
}

public void buttonSeveniron(View view) {
}

public void buttonEightiron(View view) {
}

public void buttonNineiron(View view) {
}

public void buttonPW(View view) {
}

public void buttonSW(View view) {
}

public void buttonFiftysix(View view) {
}

public void buttonSixty(View view) {
}

}

SQLiteHelper.java

package edu.tamu.thecaddyapp;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class SQLiteHelper extends SQLiteOpenHelper {

private static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = "SQLiteDatabase.db";
public static final String TABLE_NAME = "golf_averages";
public static final String _id = "_id";
public static final String COL_1 = "COL_1";
public static final String COL_2 = "COL_2";
public static final String COL_3 = "COL_3";
public static final String COL_4 = "COL_4";
public static final String COL_5 = "COL_5";
public static final String COL_6 = "COL_6";
public static final String COL_7 = "COL_7";
public static final String COL_8 = "COL_8";
public static final String COL_9 = "COL_9";
public static final String COL_10 = "COL_10";

public String create_table = "CREATE TABLE" + TABLE_NAME
        + " (_id integer primary key autoincrement, "
        + COL_1 + "text, "
        + COL_2 + "text, "
        + COL_3 + "text, "
        + COL_4 + "text, "
        + COL_5 + "text, "
        + COL_6 + "text, "
        + COL_7 + "text, "
        + COL_8 + "text, "
        + COL_9 + "text, "
        + COL_10 + "text" +")";


public SQLiteHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    Log.d("SQLiteHelper", "Context Reached");
}


@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
    sqLiteDatabase.execSQL(create_table);
    Log.d("onCreate", "onCreate reached");
}

@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
    sqLiteDatabase.execSQL("DROP TABLE IF EXISTS golf_averages");
    onCreate(sqLiteDatabase);
}
}

Answer 1

You have to add spaces in the SQL statement. You have these lines:

+ COL_9 + "text, "

but COL_9 is defined as:

public static final String COL_9 = "COL_9";

meaning the SQL statement, when compiled, ends up with COL_9 and text joined in the name, meaning the row name is COL_9text .

Add a space before you write text and it'll fix it. The issue isn't there on the first piece though (with ID), it appears to only be for the text columns.

In addition, the same issue occurs at the start of the SQL statement:

"CREATE TABLE" + TABLE_NAME

Add a space after the word TABLE .

The easiest way to spot this is happening, is to look for errors in the logcat. This shows you where your SQL syntax errors occur, and helps narrow down the changes you need to make.

Answer 2

Add Proper spacing in the query, please

public String create_table = "CREATE TABLE " + TABLE_NAME
    + " (_id integer primary key autoincrement, "
    + COL_1 + " text, "
    + COL_2 + " text, "
    + COL_3 + " text, "
    + COL_4 + " text, "
    + COL_5 + " text, "
    + COL_6 + " text, "
    + COL_7 + " text, "
    + COL_8 + " text, "
    + COL_9 + " text, "
    + COL_10 + " text" +")";

Spacing is very important in SQL Queries