嗨，这是我第一次使用JSON，我收到了这个错误
PLZ有人可以告诉我如何修复它是我的代码：
MainActivity：
private static String url = "";
//JSON Node Names
private static final String TAG_OS = "android";
private static final String TAG_VER = "ver";
private static final String TAG_NAME = "name";
private static final String TAG_API = "api";
JSONArray android = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
oslist = new ArrayList<HashMap<String, String>>();
Btngetdata = (Button)findViewById(R.id.getdata);
Btngetdata.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
new JSONParse().execute();
}
});
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
ver = (TextView)findViewById(R.id.vers);
name = (TextView)findViewById(R.id.name);
api = (TextView)findViewById(R.id.api);
pDialog = new ProgressDialog(MainActivity.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();
try {
// Getting JSON Array from URL
android = json.getJSONArray(TAG_OS);
for(int i = 0; i < android.length(); i++){
JSONObject c = android.getJSONObject(i);
// Storing JSON item in a Variable
String ver = c.getString(TAG_VER);
String name = c.getString(TAG_NAME);
String api = c.getString(TAG_API);
// Adding value HashMap key => value
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_VER, ver);
map.put(TAG_NAME, name);
map.put(TAG_API, api);
oslist.add(map);
list=(ListView)findViewById(R.id.list);
ListAdapter adapter = new SimpleAdapter(MainActivity.this, oslist,
R.layout.list_v,
new String[] { TAG_VER,TAG_NAME, TAG_API }, new int[] {
R.id.vers,R.id.name, R.id.api});
list.setAdapter(adapter);
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(MainActivity.this, "You Clicked at "+oslist.get(+position).get("name"), Toast.LENGTH_SHORT).show();
}
});
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
这是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, "utf-8"), 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
// return JSON String
try {
return new JSONObject(json.substring(json.indexOf("{"), json.lastIndexOf("}") + 1));
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return jObj;
//返回新的JSONObject（json.substring（json.indexOf（“{”），json.lastIndexOf（“}”）+ 1））; } }
和我的logcat：
07-04 07:54:39.954: E/AndroidRuntime(15437): FATAL EXCEPTION: AsyncTask #2
07-04 07:54:39.954: E/AndroidRuntime(15437): java.lang.RuntimeException: An error occured while executing doInBackground()
07-04 07:54:39.954: E/AndroidRuntime(15437): at android.os.AsyncTask$3.done(AsyncTask.java:299)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-04 07:54:39.954: E/AndroidRuntime(15437): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.lang.Thread.run(Thread.java:856)
07-04 07:54:39.954: E/AndroidRuntime(15437): Caused by: java.lang.IllegalStateException: Target host must not be null, or set in parameters. scheme=null, host=null, path=
07-04 07:54:39.954: E/AndroidRuntime(15437): at org.apache.http.impl.client.DefaultRequestDirector.determineRoute(DefaultRequestDirector.java:591)
07-04 07:54:39.954: E/AndroidRuntime(15437): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:293)
07-04 07:54:39.954: E/AndroidRuntime(15437): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:670)
07-04 07:54:39.954: E/AndroidRuntime(15437): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:509)
07-04 07:54:39.954: E/AndroidRuntime(15437): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
07-04 07:54:39.954: E/AndroidRuntime(15437): at learn2crack.listview.library.JSONParser.getJSONFromUrl(JSONParser.java:38)
07-04 07:54:39.954: E/AndroidRuntime(15437): at com.bsmat.manal.MainActivity$JSONParse.doInBackground(MainActivity.java:100)
07-04 07:54:39.954: E/AndroidRuntime(15437): at com.bsmat.manal.MainActivity$JSONParse.doInBackground(MainActivity.java:1)
07-04 07:54:39.954: E/AndroidRuntime(15437): at android.os.AsyncTask$2.call(AsyncTask.java:287)
07-04 07:54:39.954: E/AndroidRuntime(15437): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-04 07:54:39.954: E/AndroidRuntime(15437): ... 5 more
07-04 07:54:50.294: E/Ads(15437): Not enough space to show ad! Wants: <936, 120>, Has: <720, 1280>
07-04 07:54:50.299: E/Ads(15437): Not enough space to show ad! Wants: <936, 120>, Has: <720, 1280>
07-04 07:54:50.374: E/Ads(15437): Not enough space to show ad! Wants: <936, 120>, Has: <720, 1280>
07-04 07:54:50.374: E/Ads(15437): Not enough space to show ad! Wants: <936, 120>, Has: <720, 1280>
07-04 07:54:50.439: E/WindowManager(15437): Activity com.bsmat.manal.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@41d01e58 that was originally added here
07-04 07:54:50.439: E/WindowManager(15437): android.view.WindowLeaked: Activity com.bsmat.manal.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@41d01e58 that was originally added here
07-04 07:54:50.439: E/WindowManager(15437): at android.view.ViewRootImpl.<init>(ViewRootImpl.java:402)
07-04 07:54:50.439: E/WindowManager(15437): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:311)
07-04 07:54:50.439: E/WindowManager(15437): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:224)
07-04 07:54:50.439: E/WindowManager(15437): at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:149)
07-04 07:54:50.439: E/WindowManager(15437): at android.view.Window$LocalWindowManager.addView(Window.java:554)
07-04 07:54:50.439: E/WindowManager(15437): at android.app.Dialog.show(Dialog.java:277)
07-04 07:54:50.439: E/WindowManager(15437): at com.bsmat.manal.MainActivity$JSONParse.onPreExecute(MainActivity.java:88)
07-04 07:54:50.439: E/WindowManager(15437): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
07-04 07:54:50.439: E/WindowManager(15437): at android.os.AsyncTask.execute(AsyncTask.java:534)
07-04 07:54:50.439: E/WindowManager(15437): at com.bsmat.manal.MainActivity$1.onClick(MainActivity.java:65)
07-04 07:54:50.439: E/WindowManager(15437): at android.view.View.performClick(View.java:4211)
07-04 07:54:50.439: E/WindowManager(15437): at android.view.View$PerformClick.run(View.java:17267)
07-04 07:54:50.439: E/WindowManager(15437): at android.os.Handler.handleCallback(Handler.java:615)
07-04 07:54:50.439: E/WindowManager(15437): at android.os.Handler.dispatchMessage(Handler.java:92)
07-04 07:54:50.439: E/WindowManager(15437): at android.os.Looper.loop(Looper.java:137)
07-04 07:54:50.439: E/WindowManager(15437): at android.app.ActivityThread.main(ActivityThread.java:4898)
07-04 07:54:50.439: E/WindowManager(15437): at java.lang.reflect.Method.invokeNative(Native Method)
07-04 07:54:50.439: E/WindowManager(15437): at java.lang.reflect.Method.invoke(Method.java:511)
07-04 07:54:50.439: E/WindowManager(15437): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
07-04 07:54:50.439: E/WindowManager(15437): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
07-04 07:54:50.439: E/WindowManager(15437): at dalvik.system.NativeStart.main(Native Method)
07-04 07:54:50.459: E/Ads(15437): Not enough space to show ad! Wants: <936, 120>, Has: <720, 1280>
07-04 07:54:50.459: E/Ads(15437): Not enough space to show ad! Wants: <936, 120>, Has: <720, 1280>
答案 0 :(得分：0)
例外说
引起：java.lang.IllegalStateException：目标主机不能是 null，或在参数中设置。 scheme = null，host = null，path =
表示您的主机为空。你忘了指定网址。你的url变量设置为null.please pass url here
JSONObject json = jParser.getJSONFromUrl(url);
或将您的网址设置为某个内容。