我正在尝试编写将注册用户并将其添加到数据库的代码。在此之前，它将使用“数据库帮助程序”类中编写的函数检查电子邮件和用户名是否存在。问题是每次我尝试访问数据库时app崩溃
这是数据库帮助程序类：
public class DatabaseHelper extends SQLiteOpenHelper {
// database name
public static final String DATABASENAME= "Register.db";
//column names
public static final String username= "username";
public static final String email= "email";
public static final String password= "password";
public static final String wins= "wins";
public static final String losses= "losses";
public static final String points= "points";
public static final String alltimewinnings= "alltime";
public static final String ratio= "ratio";
//table create statement
private static final String CREATETABLE= "CREATE TABLE "+ "(" +username + " TEXT PRIMARY KEY," + email + " TEXT,"
+ password+ " Text" + wins + " TEXT," + losses+ "Text"+points+ "Text"+alltimewinnings+"Text"+ratio+"Text"+")";
public DatabaseHelper(Context context) {
super(context,DATABASENAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATETABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + CREATETABLE);
}
public boolean AddUser(User user) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("username", user.GetName());
contentValues.put("email", user.GetEmail());
contentValues.put("password", user.GetPassword());
contentValues.put("wins", 0);
contentValues.put("losses", 0);
contentValues.put("points", 1000);
contentValues.put("alltime",0);
contentValues.put("ratio",0);
long ins = db.insert(CREATETABLE, null, contentValues);
if (ins == 1) return false;
else return true;
}
public Boolean CheckMail (String emailaddress) //checks if email exists already
{
SQLiteDatabase db= this.getReadableDatabase();
String selectQuery = "SELECT * FROM " + CREATETABLE + " WHERE "
+ email + " = " + emailaddress;
//Log.e(, selectQuery);// SHOWS IN ERROR FOR DEBUGGING
Cursor cursor= db.rawQuery(selectQuery,null);
if(cursor.getCount()>0) return false;
else return true;
}
public Boolean CheckUserName (String name) //checks if username exists already
{
SQLiteDatabase db= this.getReadableDatabase();
String selectQuery = "SELECT * FROM " + CREATETABLE + " WHERE "
+ username + " = " + name;
//Log.e(, selectQuery);// SHOWS IN ERROR FOR DEBUGGING
Cursor cursor= db.rawQuery(selectQuery,null);
if(cursor.getCount()>0) return false;
else return true;
}
这是寄存器类：
DatabaseHelper db= new DatabaseHelper(this);// database of users
Button Register;// button of registration
EditText password;// the user's password
EditText email;//the user's email
EditText userid;// the user's name
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
Register= (Button) findViewById(R.id.register);
email= (EditText) findViewById(R.id.EMAIL);
password= (EditText) findViewById(R.id.PASSWORD);
userid= (EditText) findViewById(R.id.username);
Register.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v) {
String userId = userid.getText().toString();
String Password = password.getText().toString();
String Email = email.getText().toString();
User user= new User(userId,Password,Email);
if(user.equals("")|| Password.equals("")|| Email.equals(""))//IF ANY IF FIELDS IS NULL
{ // say the status of the registration
Toast.makeText(getApplicationContext(), "Fields are empty",Toast.LENGTH_SHORT).show();
}
else
{ Boolean checkmail= db.CheckMail(user.GetEmail());
Boolean checkusername= db.CheckUserName(user.GetName());
if(checkmail==false && checkusername==true) {
// say the status of the registration
Toast.makeText(getApplicationContext(), "Registration failed. Email already exists", Toast.LENGTH_SHORT).show();
}
else if(checkmail==true && checkusername==false) {
// say the status of the registration
Toast.makeText(getApplicationContext(), "Registration failed. Username already exists", Toast.LENGTH_SHORT).show();
}
else if(checkmail==false && checkusername==false) {
// say the status of the registration
Toast.makeText(getApplicationContext(), "Registration failed. Email and Username already exists", Toast.LENGTH_SHORT).show();
}
else
{
Boolean insert = db.AddUser(user);
if (insert == true)
{ //save the user's name in SharedPreferences before registration for access in other activities
SharedPreferences ShareName= getSharedPreferences("data",MODE_PRIVATE);
SharedPreferences.Editor editor= ShareName.edit();
editor.putString("username",userId);
editor.commit();
// say the status of the registration
Toast.makeText(getApplicationContext(), "Registration is complete", Toast.LENGTH_SHORT).show();
//move to the next page
Intent intent = new Intent(Register.this, HomePage.class);
startActivity(intent);
}
// say the status of the registration
Toast.makeText(getApplicationContext(), "Error occurred. Please try again later", Toast.LENGTH_SHORT).show();
}
}
}
});
}
}
答案 0 :(得分：0)
您的CREATE TABLE语句由于缺少逗号和空格而出现了多个错误。
更改为此：
private static final String CREATETABLE= "CREATE TABLE "+ "(" +
username + " TEXT PRIMARY KEY," + email + " TEXT," +
password + " TEXT," + wins + " TEXT," + losses + " TEXT," + points + " TEXT," +
alltimewinnings + " TEXT," + ratio + " TEXT)";
之后，从设备上卸载应用程序并重新运行。