Question

他们!!

这里我有一个非常好的JSON Parser，但是当我触摸列表中的Itme时，whol应用程序（第二个活动）崩溃了。这段代码有什么问题？任何想法？

第一项活动公共类新闻扩展了ListActivity {

// url to make request
        private static String url = "http://add.pixelartdev.com/api/get_category_index/?slug=test" +

                "";

        // JSON Node names
        private static final String TAG_POSTS = "posts";
        private static final String TAG_PURL = "url";
        private static final String TAG_TITLE = "title";
        private static final String TAG_EXCERPT = "excerpt";
        private static final String TAG_DATE = "date";

        // contacts JSONArray
        JSONArray posts = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.news);


    // Hashmap for ListView
    ArrayList<HashMap<String, String>> newsList = new ArrayList<HashMap<String, String>>();

    // Creating JSON Parser instance
    JSONParser jParser = new JSONParser();

    // getting JSON string from URL
    JSONObject json = jParser.getJSONFromUrl(url);

        try {
        // Getting Array of Contacts
        posts = json.getJSONArray(TAG_POSTS);

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

            // Storing each json item in variable
            String purl = c.getString(TAG_PURL);
            String title = c.getString(TAG_TITLE);
            String date = c.getString(TAG_DATE);

            // Phone number is agin JSON Object
         //  JSONObject phone = c.getJSONObject(TAG_AUTHOR);
         // String mobile = phone.getString(TAG_DATE);
         // String home = phone.getString(TAG_CATEGORIES);

         // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();

            // adding each child node to HashMap key => value
            map.put(TAG_PURL, purl);
            map.put(TAG_TITLE, title);
            map.put(TAG_DATE, date);

            // adding HashList to ArrayList
            newsList.add(map);

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

    /**
     * Updating parsed JSON data into ListView
     * */
    ListAdapter adapter = new SimpleAdapter(this, newsList,
            R.layout.list_item,
            new String[] { TAG_TITLE, TAG_DATE,  TAG_PURL }, new int[] {
                    R.id.title, R.id.date, R.id.slugurl, });

    setListAdapter(adapter);

    // selecting single ListView item
    ListView lv = getListView();

    // Launching new screen on Selecting Single ListItem
    lv.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {

            // getting values from selected ListItem
            String TAG_KURL = ((TextView) view.findViewById(R.id.slugurl)).getText().toString();
                 String purl = TAG_KURL;
            // Starting new intent
            Intent postin = new Intent(news.this, post.class);          
            postin.putExtra(TAG_KURL, purl);
            startActivity(postin);
        }
    });
}

}

第二项活动 ublic class post扩展了Activity {

private static String kurl = "TAG_KURL";

            // JSON Node names
            private static final String TAG_POST = "posts";
            private static final String TAG_TITLE = "title";
            private static final String TAG_CONTENT = "excerpt";

            // contacts JSONArray
            JSONArray post = null;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.post);


        // Creating JSON Parser instance
        JSONParser jParser = new JSONartParser();

        // getting JSON string from URL
        JSONObject json = jParser.getJSONFromUrl(getIntent().getStringExtra("TAG_KURL"));

            try {
            // Getting Array of Contacts
            post = json.getJSONArray(TAG_POST);

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

                // Storing each json item in variable
                String title = c.getString(TAG_TITLE);
                String content = c.getString(TAG_CONTENT);

             // creating new HashMap
                HashMap<String, String> map = new HashMap<String, String>();

                // adding each child node to HashMap key => value
                map.put(TAG_TITLE, title);
                map.put(TAG_CONTENT, content);



                TextView lblTitle = (TextView) findViewById(R.id.post_title_label);
                TextView lblContent = (TextView) findViewById(R.id.post_content_label);

                lblTitle.setText(title);
                lblContent.setText(content);    


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

}

JSON Parser 公共类JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

public JSONObject getJSONFromUrl(String url) {

    // Making HTTP request
    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        is = httpEntity.getContent();          

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
        is.close();
        json = sb.toString();
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }

    // try parse the string to a JSON object
    try {
        jObj = new JSONObject(json);
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    // return JSON String
    return jObj;

}

}

Answer 1

您可能在以下行中出现Null Pointer Exception：

JSONObject json = jParser.getJSONFromUrl(getIntent().getStringExtra("TAG_KURL"));

可能会发生这种情况，因为getIntent().getStringExtra("TAG_KURL")正在返回 null 。为什么？你错过了报价 postin.putExtra(TAG_KURL, purl);。

因此，如果编辑如下：postin.putExtra("TAG_KURL", purl);

，您的问题将得到解决

android JSON Parser不工作

1 个答案: