如何使用数据库中的所有值检查qr代码值

Question

我试图检查扫描的qr代码是否与我的一个sql帖子相同。 如果与我的一个sql帖子匹配，则此帖子在接下来的4天内不可用。我尝试了以下检查这个qr值：

public class Konto  extends AppCompatActivity implements ZXingScannerView.ResultHandler {
private TextView txtName;
private ImageButton btnLogout;
private String TAG = Locations.class.getSimpleName();

private ProgressDialog pDialog;
String qr_result;

// URL to get contacts JSON
private static String url = "yxxx";

ArrayList<HashMap<String, String>> contactList;

private SQLiteHandler db;
private SessionManager session;

private ZXingScannerView mScannerView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_konto
    );
    new GetContacts().execute();
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
        if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA)) {
            AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
            alertBuilder.setCancelable(false);
            alertBuilder.setTitle("Permission necessary");
            alertBuilder.setMessage("Fine Location is necessary");
            alertBuilder.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {

                @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCompat.requestPermissions(Konto.this, new String[]{Manifest.permission.CAMERA}, 1234);
                }
            });

            AlertDialog alert = alertBuilder.create();
            alert.show();
        } else {
            ActivityCompat.requestPermissions(Konto.this, new String[]{Manifest.permission.CAMERA}, 1234);
        }

    }
    ImageButton test = (ImageButton) findViewById(R.id.testforsql);
    test.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mScannerView = new ZXingScannerView(Konto.this);
            setContentView(mScannerView);
            mScannerView.setResultHandler(Konto.this);
            mScannerView.startCamera();


        }
    });


    txtName = (TextView) findViewById(R.id.kontoname);

    btnLogout = (ImageButton) findViewById(R.id.logoutbtn);

    // SqLite database handler
    db = new SQLiteHandler(getApplicationContext());

    // session manager
    session = new SessionManager(getApplicationContext());

    if (!session.isLoggedIn()) {
        logoutUser();
    }

    // Fetching user details from sqlite
    HashMap<String, String> user = db.getUserDetails();

    String name = user.get("name");
    String email = user.get("email");

    // Displaying the user details on the screen
    txtName.setText(name);


    // Logout button click event
    btnLogout.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            logoutUser();
        }
    });
    contactList = new ArrayList<>();


}

@Override
public void handleResult(Result result) {
    Log.w("handleResult", result.getText());
    AlertDialog.Builder builder = new AlertDialog.Builder(Konto.this);
    builder.setTitle("Scan Result");
    builder.setMessage(result.getText());
    AlertDialog alertDialog = builder.create();
    alertDialog.show();
    qr_result = result.getText();
    mScannerView.resumeCameraPreview(Konto.this);

}

/**
 * Logging out the user. Will set isLoggedIn flag to false in shared
 * preferences Clears the user data from sqlite users table
 */
private void logoutUser() {
    session.setLogin(false);

    db.deleteUsers();

    // Launching the login activity
    Intent intent = new Intent(Konto.this, LoginActivity.class);
    startActivity(intent);
    finish();
}

private class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(Konto.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();

    }

    @Override
    protected Void doInBackground(Void... arg0) {
        HttpHandler sh = new HttpHandler();

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(url);

        Log.e(TAG, "Response from url: " + jsonStr);

        if (jsonStr != null) {
            try {
                JSONArray contacts = new JSONArray(jsonStr);

                // Getting JSON Array node


                // looping through All Contacts
                for (int i = 0; i < contacts.length(); i++) {
                    JSONObject c = contacts.getJSONObject(i);

                    String id = c.getString("id");
                    String name = c.getString("name");
                    String street = c.getString("street");
                    String postalcode = c.getString("postalcode");
                    String entry = c.getString("entry");
                    String opening = c.getString("opening");
                    String agegroup = c.getString("agegroup");
                    String imageurl = c.getString("imageurl");
                    String urlbtn = c.getString("urlbtn");
                    String Fsk = c.getString("Fsk");
                    String city = c.getString("city");
                    String lat = c.getString("lat");
                    String lng = c.getString("lng");
                    String bg = c.getString("background");
                    String qr = c.getString("qr");
                    HashMap<String, String> contact = new HashMap<>();

                    // adding each child node to HashMap key => value
                    contact.put("id", id);
                    contact.put("name", name);
                    contact.put("street", street);
                    contact.put("postalcode", postalcode);
                    contact.put("entry", entry);
                    contact.put("opening", opening);
                    contact.put("agegroup", agegroup);
                    contact.put("imageurl", imageurl);
                    contact.put("urlbtn", urlbtn);
                    contact.put("Fsk", Fsk);
                    contact.put("city", city);
                    contact.put("lat", lat);
                    contact.put("lng", lng);
                    contact.put("background", bg);
                    contact.put("qr",qr);
                    // adding contact to contact list
                    contactList.add(contact);

                }
            } catch (final JSONException e) {
                Log.e(TAG, "Json parsing error: " + e.getMessage());
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Json parsing error: " + e.getMessage(),
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }
        } else {
            Log.e(TAG, "Couldn't get json from server.");
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(),
                            "Couldn't get json from server. Check LogCat for possible errors!",
                            Toast.LENGTH_LONG)
                            .show();
                }
            });

        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        // Dismiss the progress dialog
        if (pDialog.isShowing())
            pDialog.dismiss();

        for (final HashMap<String, String> contact : contactList){
          contact.get("qr");
           if (qr_result.equals(contact.get("qr"))){
                Toast.makeText(getApplicationContext(),"QR Accepted",Toast.LENGTH_LONG).show();
            }else{
                Toast.makeText(getApplicationContext(),"NOt goog",Toast.LENGTH_LONG).show();
            }
        }
    }
}

}