Android Studio | Asynctask | 尝试解析JSON时JSON接收到空对象引用错误

Question

As the title suggests, I'm having an issue parsing JSON data from a URL with an asynctask in Android Studio. I keep receiving a Null Object Reference error, however if I use the below code in an Eclipse Enterprise project (without the asynctask code, just a regular application), I'm able to parse the JSON just fine. Also, the internet works on my emulator, as I am able to access Google on the web browser. Could you guys point me in the right direction on how to overcome this issue? I have tried everything that I could think of, and I'm just confused because the code works in a regular Eclipse Java Application project, yet doesn't work in Android Studio.

Asynctask Code: @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_buy_item);

        class CallDBQuery extends AsyncTask<URL, Void, Item> {
            protected Item doInBackground(URL...url) {
                try {
                    URL urls = new   
                URL("XXX");

                    ObjectMapper mapper = new ObjectMapper();
    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, 
    false);

                    //Item Items = mapper.readValue(urls, Item.class);

                    return mapper.readValue(urls, Item.class);
                }
                catch(Exception e) {
                    e.printStackTrace();
                    return null;
                }
            }
            protected void onPostExecute(Item Items) {
                TextView fieldTxt = (TextView)   
                findViewById(R.id.View2);

       fieldTxt.setText(Items.getItems().get(0).GetTitle().toString());
            }
        }
        try {
            URL url = new 
                URL("XXX");

            new CallDBQuery().execute(url);
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    }

Note: Commented out the Items Item = mapper.readValue() part because I was receiving a "Redundant variable message", but even when I was using this bit of code, and returning "Items", I still received the Null Object Reference

JSON:

{"Items":[{"Email":"jared.hart1@gmail.com","Description":"Surface Pro 4  
for sale, in excellent condition, basically brand 
new!","Phone":"4077603835","Title":"Surface Pro 4","Id":"1"},
{"Email":null,"Description":null,"Phone":null,"Title":"Macbook 
Air","Id":"2"},{"Email":"jhart@radixx.com","Description":"Free Macbook 
Air, I promise","Phone":"3433215565","Title":"Lenovo 
Laptop","Id":"3"}]}

JSON Class Item:

public class Item {
    @JsonProperty
    private List<ItemDetails> Items = new ArrayList<ItemDetails>();

    public List<ItemDetails> getItems() {return this.Items;}
    public void setItems(List<ItemDetails> Items) {this.Items = Items;}
}

JSON Class ItemDetails:

public class ItemDetails {
    @JsonProperty
    private String Id;

    @JsonProperty
    private String Title;

    @JsonProperty
    private String Phone;

    @JsonProperty
    private String Email;

    @JsonProperty
    private String Description;

    public String GetId() {return this.Id;}
    public void SetId(String Id) {this.Id = Id;}

    public String GetTitle() {return this.Title;}
    public void SetTitle(String Title) {this.Title = Title;}

    public String GetPhone() {return this.Phone;}
    public void SetPhone(String Phone) {this.Phone = Phone;}

    public String GetEmail() {return this.Email;}
    public void SetEmail(String Email) {this.Email = Email;}

    public String GetDescription() {return this.Description;}
    public void SetDescription(String Description) {this.Description =  
    Description;}
}

Answer 1

I figured it out!! In my Manifest file, I had inside the application tag. I debugged my application, and discovered that I was getting the Null value from the catch block of my code, due to an Internet Security Permission Exception. After adding the code outside of the application tag, everything worked!