When I try to run my application, it crashes again and again. below is the method that I have created in DBHandler.java file

public Cursor CheckUsername() {
        SQLiteDatabase db = this.getReadableDatabase();
        String query = "SELECT * FROM register WHERE Username = "  MainActivity.getValue()  " and password = " MainActivity.getpassword() ";";
        return db.rawQuery(query,null);
    }

So to check whether username and password is correct I have also created checklogin() method in MainActivity.java below is the code

 private void checkLogin() {
        final EditText editText = findViewById(R.id.emaillogin);
        final EditText editText1 = findViewById(R.id.passwordlogin);

        //editText.setText("");
        password = editText1.getText().toString();
        //editText1.setText("");
        username = editText.getText().toString().trim();

        Cursor c = dbHandler.CheckUsername();
        if (c.moveToFirst()) {
            do {
                Toast.makeText(MainActivity.this, "Login Success", Toast.LENGTH_LONG).show();
                Intent intent = new Intent(MainActivity.this, MainActivity2.class);
                startActivity(intent);
            }
            while (c.moveToNext());
        }


    }

When I try to debug it shows

E/SQLiteLog: (1) no such column: rushi
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.software2.bloodbankmanagement, PID: 27590
    android.database.sqlite.SQLiteException: no such column: rushi (code 1): , while compiling: SELECT * FROM register WHERE Username = rushi and password = 4567;
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:890)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:501)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
        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:1404)
        at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1336)
        at com.example.software2.bloodbankmanagement.DBHandler.CheckUsername(DBHandler.java:176)
        at com.example.software2.bloodbankmanagement.MainActivity.checkLogin(MainActivity.java:94)
        at com.example.software2.bloodbankmanagement.MainActivity.access$000(MainActivity.java:31)
        at com.example.software2.bloodbankmanagement.MainActivity$1.onClick(MainActivity.java:70)
        at android.view.View.performClick(View.java:6412)
        at android.view.View$PerformClick.run(View.java:25341)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:6977)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:528)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:910)

CodePudding user response：

check out with this query

String query = "SELECT * FROM register WHERE Username = '"  MainActivity.getValue()  "' and password = '" MainActivity.getpassword() "';";

note ' character before and after every String. this should produce below query

SELECT * FROM register WHERE Username = 'value' and password = 'password';

btw. passing data with static reference kept in Activity (e.g. MainActivity.getValue()) is a VERY bad aproach, it leads you to future memory leaks. you should pass these credentials to checkLogin method. also handling database in main thread is very bad for performance, when your database grow then searching in it would be taking some time, during it you apps UI will be freezed. strongly consider threading, coroutines, just any async way for processing data