我正在尝试使用 JSON 创建一个显示来自 tumblr 帐户的图像的应用程序。我通过更改我为一个几乎做同样事情的 twitter 应用程序所拥有的一些代码来做到这一点。不幸的是，我发现 tumblr api 更难使用，而且我能找到的所有示例都是为 php 制作的，因此无济于事。此行的 nullPointerException：
for (int i = 0; i < arr.length(); i++) {
JSON 通过 jsonlint.com 进行验证，如下所示：
"meta": {
"status": 200,
"msg": "OK"
},
"response": {
"blog": {
"title": "Facts and Chicks",
"posts": 789,
"name": "factsandchicks",
"url": "http://factsandchicks.com/",
"updated": 1347565227,
"description": "Random facts and hot chicks, the best way to learn.\nWebsite and Concept by: GustoNYC",
"ask": false
},
"posts": [
{
"blog_name": "factsandchicks",
"id": 31474135003,
"post_url": "http://factsandchicks.com/post/31474135003/ups-was-founded-by-two-teenagers-with-one-bicycle",
"slug": "ups-was-founded-by-two-teenagers-with-one-bicycle",
"type": "photo",
"date": "2012-09-13 19:37:59 GMT",
"timestamp": 1347565079,
"state": "published",
"format": "html",
"reblog_key": "iWEenkAh",
"tags": [
"facts",
"factsandchicks",
"chicks",
"UPS",
"teenagers",
"friends",
"business",
"America",
"WTF",
"money",
"inspiration",
"history"
],
"highlighted": [],
"note_count": 241,
"source_url": "http://factsandchicks.com",
"source_title": "factsandchicks.com",
"caption": "<p>UPS was founded by two teenagers with one bicycle and $100 Borrowed from a Friend.</p>\n<p><a href=\"http://www.ups.com/content/corp/about/history/1929.html\" target=\"_blank\">source</a></p>",
"link_url": "http://factsandchicks.com",
"photos": [
{
"caption": "",
"alt_sizes": [
{
"width": 640,
"height": 960,
"url": "http://25.media.tumblr.com/tumblr_m8fz0bLjJU1r3tp7bo1_1280.jpg"
},
{
"width": 500,
"height": 750,
"url": "http://25.media.tumblr.com/tumblr_m8fz0bLjJU1r3tp7bo1_500.jpg"
},
{
"width": 400,
"height": 600,
"url": "http://24.media.tumblr.com/tumblr_m8fz0bLjJU1r3tp7bo1_400.jpg"
},
{
"width": 250,
"height": 375,
"url": "http://25.media.tumblr.com/tumblr_m8fz0bLjJU1r3tp7bo1_250.jpg"
},
{
"width": 100,
"height": 150,
"url": "http://24.media.tumblr.com/tumblr_m8fz0bLjJU1r3tp7bo1_100.jpg"
},
{
"width": 75,
"height": 75,
"url": "http://24.media.tumblr.com/tumblr_m8fz0bLjJU1r3tp7bo1_75sq.jpg"
}
],
"original_size": {
"width": 640,
"height": 960,
"url": "http://25.media.tumblr.com/tumblr_m8fz0bLjJU1r3tp7bo1_1280.jpg"
}
}
]
},
我的代码如下所示：
public class Example extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ArrayList<Tweet> tweets;
try {
tweets = getTweets();
ListView listView = (ListView) findViewById(R.id.ListViewId);
listView.setAdapter(new UserItemAdapter(this, R.layout.listitem,
tweets));
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public class UserItemAdapter extends ArrayAdapter<Tweet> {
private ArrayList<Tweet> tweets;
public UserItemAdapter(Context context, int imageViewResourceId,
ArrayList<Tweet> tweets) {
super(context, imageViewResourceId, tweets);
this.tweets = tweets;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.listitem, null);
}
Tweet tweet = tweets.get(position);
if (tweet != null) {
ImageView image = (ImageView) v.findViewById(R.id.avatar);
if (image != null) {
image.setImageBitmap(getBitmap(tweet.image_url));
}
}
return v;
}
}
public Bitmap getBitmap(String bitmapUrl) {
try {
URL url = new URL(bitmapUrl);
return BitmapFactory.decodeStream(url.openConnection()
.getInputStream());
} catch (Exception ex) {
return null;
}
}
public ArrayList<Tweet> getTweets() throws ClientProtocolException,
IOException, JSONException {
String searchUrl = "http://api.tumblr.com/v2/blog/factsandchicks.com/posts?api_key=API_KEY";
ArrayList<Tweet> tweets = new ArrayList<Tweet>();
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(searchUrl);
ResponseHandler<String> responseHandler = new BasicResponseHandler();
String responseBody = null;
try {
responseBody = client.execute(get, responseHandler);
} catch (Exception ex) {
ex.printStackTrace();
}
JSONArray posts = JSONObject.getJSONObject("response").getJSONArray(
"posts");
for (int i = 0; i < posts.length(); i++) {
JSONArray photos = posts.getJSONObject(i).getJSONArray("photos");
for (int j = 0; j < photos.length(); j++) {
JSONObject photo = photos.getJSONObject(j);
String url = photo.getJSONArray("alt_sizes").getJSONObject(0)
.getString("url");
Tweet tweet = new Tweet(url);
tweets.add(tweet);
}
return tweets;
}
public class Tweet {
public String image_url;
public Tweet(String url) {
this.image_url = url;
}
}
}
我不知道为什么这不起作用，因为我可以使它适用于 twitter。任何帮助都会得到帮助！