Android CursorIndexOutOfBoundsException无法解析
我将光标索引设置为超出范围“请求索引0:大小为0”。它只是一个用户注册和登录应用程序。当没有用户名和密码匹配的用户时,我的应用程序将崩溃 代码如下: MainActivity.javaAndroid CursorIndexOutOfBoundsException无法解析,android,android-cursor,Android,Android Cursor,我将光标索引设置为超出范围“请求索引0:大小为0”。它只是一个用户注册和登录应用程序。当没有用户名和密码匹配的用户时,我的应用程序将崩溃 代码如下: MainActivity.java final SUSQLiteHelper dbhelper = new SUSQLiteHelper(this); LoginData login = dbhelper.readOneUser(loginuname.getText().toString(), loginpwd.getText().toStrin
final SUSQLiteHelper dbhelper = new SUSQLiteHelper(this);
LoginData login = dbhelper.readOneUser(loginuname.getText().toString(), loginpwd.getText().toString());
if(login.getUname().toString().equals(loginuname.getText().toString()) &&
login.getPwd().toString().equals(loginpwd.getText().toString()))
{
Toast.makeText(getApplicationContext(), "Login Successfull. Welcome " + login.getUname().toUpperCase() +" !".toString(),
Toast.LENGTH_LONG).show();
}
else if(login.getUname().toString().equals(loginuname.getText().toString()) &&
!login.getPwd().toString().equals(loginpwd.getText().toString()))
{
Toast.makeText(getApplicationContext(), "Login Failed. Incorrect password !",
Toast.LENGTH_LONG).show();
}
else
Toast.makeText(getApplicationContext(), "Login Failed. User doesn't exist !",
Toast.LENGTH_LONG).show(); //it never goes here if no username is found in the table
public LoginData readOneUser(String uname, String pwd)
{
SQLiteDatabase loginUserDB = this.getReadableDatabase();
LoginData newLogin = null;
Cursor cursor = loginUserDB.query(TABLE_NAME, new String[]{TABLE_ROW_UNAME, TABLE_ROW_EMAIL, TABLE_ROW_PWD}, TABLE_ROW_UNAME + "=?",
new String[]{String.valueOf(uname)}, null, null, null);
if(cursor.moveToFirst())
{
newLogin = new LoginData(cursor.getString(0), cursor.getString(1), cursor.getString(2));
}
cursor.close();
loginUserDB.close();
return newLogin;
}
SUSQLiteHelper.java
final SUSQLiteHelper dbhelper = new SUSQLiteHelper(this);
LoginData login = dbhelper.readOneUser(loginuname.getText().toString(), loginpwd.getText().toString());
if(login.getUname().toString().equals(loginuname.getText().toString()) &&
login.getPwd().toString().equals(loginpwd.getText().toString()))
{
Toast.makeText(getApplicationContext(), "Login Successfull. Welcome " + login.getUname().toUpperCase() +" !".toString(),
Toast.LENGTH_LONG).show();
}
else if(login.getUname().toString().equals(loginuname.getText().toString()) &&
!login.getPwd().toString().equals(loginpwd.getText().toString()))
{
Toast.makeText(getApplicationContext(), "Login Failed. Incorrect password !",
Toast.LENGTH_LONG).show();
}
else
Toast.makeText(getApplicationContext(), "Login Failed. User doesn't exist !",
Toast.LENGTH_LONG).show(); //it never goes here if no username is found in the table
public LoginData readOneUser(String uname, String pwd)
{
SQLiteDatabase loginUserDB = this.getReadableDatabase();
LoginData newLogin = null;
Cursor cursor = loginUserDB.query(TABLE_NAME, new String[]{TABLE_ROW_UNAME, TABLE_ROW_EMAIL, TABLE_ROW_PWD}, TABLE_ROW_UNAME + "=?",
new String[]{String.valueOf(uname)}, null, null, null);
if(cursor.moveToFirst())
{
newLogin = new LoginData(cursor.getString(0), cursor.getString(1), cursor.getString(2));
}
cursor.close();
loginUserDB.close();
return newLogin;
}
loginda.java
final SUSQLiteHelper dbhelper = new SUSQLiteHelper(this);
LoginData login = dbhelper.readOneUser(loginuname.getText().toString(), loginpwd.getText().toString());
if(login.getUname().toString().equals(loginuname.getText().toString()) &&
login.getPwd().toString().equals(loginpwd.getText().toString()))
{
Toast.makeText(getApplicationContext(), "Login Successfull. Welcome " + login.getUname().toUpperCase() +" !".toString(),
Toast.LENGTH_LONG).show();
}
else if(login.getUname().toString().equals(loginuname.getText().toString()) &&
!login.getPwd().toString().equals(loginpwd.getText().toString()))
{
Toast.makeText(getApplicationContext(), "Login Failed. Incorrect password !",
Toast.LENGTH_LONG).show();
}
else
Toast.makeText(getApplicationContext(), "Login Failed. User doesn't exist !",
Toast.LENGTH_LONG).show(); //it never goes here if no username is found in the table
public LoginData readOneUser(String uname, String pwd)
{
SQLiteDatabase loginUserDB = this.getReadableDatabase();
LoginData newLogin = null;
Cursor cursor = loginUserDB.query(TABLE_NAME, new String[]{TABLE_ROW_UNAME, TABLE_ROW_EMAIL, TABLE_ROW_PWD}, TABLE_ROW_UNAME + "=?",
new String[]{String.valueOf(uname)}, null, null, null);
if(cursor.moveToFirst())
{
newLogin = new LoginData(cursor.getString(0), cursor.getString(1), cursor.getString(2));
}
cursor.close();
loginUserDB.close();
return newLogin;
}
此类具有Uname、Pwd、Email字段的getter和setter方法,以及将这些字段作为参数的构造函数。在函数readOneUser()中,检查:
CursorIndexOutOfBoundsException:请求索引0,大小为0
这意味着cursor.moveToFirst()返回false
,并且光标为空。因此,请尝试添加代码段来检查游标是否为null,这取决于修改逻辑的方式
public LoginData readOneUser(String uname, String pwd)
{
SQLiteDatabase loginUserDB = this.getReadableDatabase();
LoginData newLogin = null;
Cursor cursor = loginUserDB.query(TABLE_NAME, new String[]{TABLE_ROW_UNAME, TABLE_ROW_EMAIL,TABLE_ROW_PWD}, TABLE_ROW_UNAME + "=?",new String[]{String.valueOf(uname)}, null, null, null);
if(cursor!=null) //Check whether cursor is null or not
{
if(cursor.moveToFirst())
{
newLogin = new LoginData(cursor.getString(0), cursor.getString(1), cursor.getString(2));
}
}
cursor.close();
loginUserDB.close();
return newLogin;
}
@这是我的日志。。。01-09 19:12:16.440:E/AndroidRuntime(308):android.database.CursorIndexOutOfBoundsException:请求索引0,大小为0