无法停止在我的应用程序中显示来自json解析器的重复数据

Question

I have an app that receives json data from a website and then parse it to show on my app programmatically. The problem that I am facing right now is if i close the app and restart it, the same data gets repeated and that I don't want. So please someone help me to solve this. Following is the code of the class that maps the data into my app.

public class FirstScreen extends Activity {
// int numberquantity;
JSONParse Jp=new JSONParse();


// URL to get JSON Array
private static String url = "http://10.0.2.2/SUPERSHOP/supershop_api.php";


private static final String TAG_USER = "record";
private static final String TAG_NAME = "Name";
private static final String TAG_PRICE = "Price";
private static final String TAG_IMAGE_PATH="http://10.0.2.2/bootstrap-dist/images/";

private static final String TAG_DESCRIPTION = "Description";



JSONArray user = null;
//  private ProgressDialog pDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Controller aController = (Controller) getApplicationContext();
    aController.getCart().clearCart();
    Jp.execute();


}

Bitmap drawable_from_url(String url) throws java.net.MalformedURLException, java.io.IOException {
    Bitmap x;

    HttpURLConnection connection = (HttpURLConnection)new URL(url) .openConnection();
    connection.setRequestProperty("User-agent","Mozilla/4.0");

    connection.connect();
    InputStream input = connection.getInputStream();

    x = BitmapFactory.decodeStream(input);
    return x;
 }


private class JSONParse extends AsyncTask<String, String, JSONObject> {
    private ProgressDialog pDialog;



    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(FirstScreen.this);
        pDialog.setMessage("Getting Data ...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show();
    }

    @Override
    protected JSONObject doInBackground(String... args) {
        JSONParser jParser = new JSONParser();
        // Getting JSON from URL
        JSONObject json = jParser.getJSONFromUrl(url);
        return json;
    }

    @Override
    protected void onPostExecute(JSONObject json) {
        pDialog.dismiss();
        Controller aController = (Controller) getApplicationContext();
        ModelProducts productObject = null;




        JSONObject c=null;
        try {
            // Getting JSON Array
            user = json.getJSONArray(TAG_USER);


            for(int i=0;i<user.length();i++){


                 c = user.getJSONObject(i);
                // Storing JSON item in a Variable
                    String name = c.getString(TAG_NAME);
                    String prices= c.getString(TAG_PRICE);  
                    int price=Integer.parseInt(prices);
                    String description = c.getString(TAG_DESCRIPTION);  

                    String imagePath=c.getString("Picture");

                    String Url=imagePath;







                    // Create product model class object


                    productObject = new ModelProducts(name,description,Url, price, 0, 0);

                    // store product object to arraylist in controller
                    aController.setProducts(productObject);




                    onResume();


            }


        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

/******************end of parser****************************/

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();


    Bitmap bitmap;

    // ImageLoader class instance
    ImageLoader imgLoader = new ImageLoader(getApplicationContext());





    setContentView(R.layout.firstscreen);

    final LinearLayout lm = (LinearLayout) findViewById(R.id.linearMain);
    final Button secondBtn = (Button) findViewById(R.id.second);
    ModelProducts productObject = null;

    // Get Global Controller Class object (see application tag in
    // AndroidManifest.xml)
    final Controller aController = (Controller) getApplicationContext();





    /****************** Products Data Creation Begins ***********/

    /******* Create view elements dynamically and show on activity ******/

    // Product arraylist size
    int ProductsSize = aController.getProductsArraylistSize();

    // create the layout params that will be used to define how your
    // button will be displayed
    LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
            LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);

    /******** Dynamically create view elements - Start **********/

    for (int j = 0; j < ProductsSize; j++) {
        // Get probuct data from product data arraylist


        String pName = aController.getProducts(j).getProductName();
        final String pDsc = aController.getProducts(j).getProductDesc();
        String pUrl=aController.getProducts(j).getImageUrl();
        final int pPrice = aController.getProducts(j).getProductPrice();
        // int pQuantity = aController.getProducts(j).getProductQuantity();
        //Toast.makeText(FirstScreen.this,pUrl, Toast.LENGTH_SHORT).show();

        // Create LinearLayout to view elemnts
        LinearLayout ll = new LinearLayout(this);
        ll.setOrientation(LinearLayout.HORIZONTAL);



        // settingup images to show in cataglog
        ImageView image = new ImageView(this);

        imgLoader.DisplayImage("http://10.0.2.2/bootstrap-dist/"+pUrl, image);


        //ll.addView(image);
        ll.addView(image);

        TextView product = new TextView(this);
        product.setText(" " + pName + "    ");

        // Add textView to LinearLayout
        ll.addView(product);

        TextView price = new TextView(this);
        price.setText(pPrice +":  Tk"+ "     ");

        // Add textView to LinearLayout
        ll.addView(price);

        TextView quantity = new TextView(this);
        quantity.setText(" " + "Quantity:" + "    ");

        // Add textView to LinearLayout
        ll.addView(quantity);

        final EditText inpquantity = new EditText(this);
        inpquantity.setText("1");

        ll.addView(inpquantity);

        final Button btn = new Button(this);
        btn.setId(j + 1);
        ModelProducts tempProductObject = aController.getProducts(j);
        if (!aController.getCart().checkProductInCart(tempProductObject)) {
            btn.setText("Add To Cart");
        }else{
            btn.setText("Added");
        }
        //btn.setText("Add To Cart");

        // set the layoutParams on the button
        btn.setLayoutParams(params);

        final int index = j;

        //to stop the keypad from popping up

        this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);



        // Created click listener for dynamically created button
        btn.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {

                int numberquantity = Integer.parseInt(inpquantity.getText()
                        .toString());
                int trackID = 0;

                // ModelProducts productobj=new ModelProducts(pName, pDsc,
                // pPrice,numberquantity);
                aController.updateProduct(index).setProductQuantity(
                        numberquantity);

                // Clicked button index
                Log.i("TAG", "index :" + index);

                // Get product instance for index
                ModelProducts tempProductObject = aController
                        .getProducts(index);

                // Check Product already exist in Cart or Not
                if (!aController.getCart().checkProductInCart(
                        tempProductObject)) {

                    btn.setText("Added");

                    // saving data of button id of items added to cart to a
                    // shared preference.
                    trackID = btn.getId();

                    // Product not Exist in cart so add product to
                    // Cart product arraylist

                    aController.getCart().setProducts(tempProductObject);

                    Toast.makeText(
                            getApplicationContext(),
                            "Now Cart size: "
                                    + aController.getCart().getCartSize(),
                            Toast.LENGTH_LONG).show();



                } 
            }
        });

        // Add button to LinearLayout
        ll.addView(btn);

        // Add LinearLayout to XML layout
        lm.addView(ll);
    }

    // aController.getProductsArraylist().clear();
    /******** Dynamically create view elements - End **********/

    secondBtn.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {

            Intent i = new Intent(getBaseContext(), Secondscreen.class);
            startActivity(i);
        }
    });
}




}

Answer 1

I'm not sure what you mean by repeating itself. Do you mean you get the json data twice or do you mean it downloads the json data again?

Anyway, as far you execute the json Parse on the onCreate, the json data will downloaded each time you close and open the Activity again.

Also don't use onResume as a function. It looks like everytime you reenter the Activity the JSON Parser and as well the Android LifeCycle opens the onResume. This means, your setting TextViews code in onResume is executed twice, because the JSON Parser and the normal onResume Call will be executed twice. Try to move the code in onResume somewhere else and then call this method in onPostExecute.

Answer 2

每次调用时，您都必须清除ModelProducts.class