b1.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {


        cv.put(DateBase.KEY_IDME,editText.getText().toString());
        cv.put(DateBase.KEY_TO,"k");
        cv.put(DateBase.KEY_DATA,editText.getText().toString());
        db.insert(DateBase.TABLE_CONTACTS,null,contentValues);

        Toast toast = Toast.makeText(getApplicationContext(),
                "Пора покормить кота!", Toast.LENGTH_SHORT);
        toast.show();

    }
});

Error inserting android.database.sqlite.SQLiteException: near "null": syntax error (code 1): , while compiling: INSERT INTO cont(null) VALUES (NULL)

db.insert(DateBase.TABLE_CONTACTS,null,contentValues);