我试图从我的应用程序本地存储的文件中获取JSON信息 . 我的代码收到以下错误,我想知道是否有人能够给出任何指针如何解决它 . 我也会附上错误和代码 .
10-11 15:02:27.277 9184-9209 / info.androidhive.jsonparsing E / AndroidRuntime:FATAL EXCEPTION:AsyncTask#1进程:info.androidhive.jsonparsing,PID:9184 java.lang.RuntimeException:执行时发生错误do.Background()在android.os.AsyncTask $ 3.done(AsyncTask.java:354)java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)java.util.concurrent.FutureTask.setException(FutureTask.java) :252)at java.util.concurrent.FutureTask.run(FutureTask.java:271)at android.os.AsyncTask $ SerialExecutor $ 1.run(AsyncTask.java:245)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor) .java:1167)java.util.concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:641)at java.lang.Thread.run(Thread.java:764)引起:java.lang.NullPointerException:Attempt to在info.androidhive.jsonparsing.MainActivity $ GetContacts.doInBac上的空对象引用上调用虚方法'org.json.JSONArray org.json.JSONObject.getJSONArray(java.lang.String)' kground(MainActivity.java:101)位于java.util.concurrent的android.os.AsyncTask $ 2.call(AsyncTask.java:333)的info.androidhive.jsonparsing.MainActivity $ GetContacts.doInBackground(MainActivity.java:52) . FutureTask.run(FutureTask.java:266)位于java.util的java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)的android.os.AsyncTask $ SerialExecutor $ 1.run(AsyncTask.java:245) . concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:641)at java.lang.Thread.run(Thread.java:764)10-11 15:02:27.289 9184-9209 / info.androidhive.jsonparsing I / Process:发送信号 . PID:9184 SIG:9
public class MainActivity extends AppCompatActivity {
private String TAG = MainActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView lv;
ArrayList<HashMap<String, String>> contactList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
contactList = new ArrayList<>();
lv = (ListView) findViewById(R.id.list);
GetContacts task = new GetContacts(this.getApplicationContext());
task.execute();
}
/**
* Async task class to get json by making HTTP call
*/
private class GetContacts extends AsyncTask<Void, Void, Void> {
private Context mContext;
public GetContacts (Context context){
mContext = context;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
//pDialog = new ProgressDialog(MainActivity.this);
//pDialog.setMessage("Please wait...");
// pDialog.setCancelable(false);
// pDialog.show();
}
private JSONObject loadJSONFromAsset() {
String inFile = "test.json";
JSONObject assetJson = null;
try {
InputStream stream = mContext.getAssets().open(inFile);
int size = stream.available();
byte[] buffer = new byte[size];
stream.read(buffer);
stream.close();
String assetString = new String(buffer);
assetJson = new JSONObject(assetString);
} catch (IOException e) {
// Handle IO exceptions here
} catch (JSONException e) {
// Handle JSON exceptions here
}
return assetJson;
}
@Override
protected Void doInBackground(Void... arg0) {
try {
JSONObject jsonObj = loadJSONFromAsset();
JSONArray contacts = jsonObj.getJSONArray("contacts");
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String id = c.getString("id");
String name = c.getString("name");
String email = c.getString("email");
String address = c.getString("address");
String gender = c.getString("gender");
JSONObject phone = c.getJSONObject("phone");
String mobile = phone.getString("mobile");
String home = phone.getString("home");
String office = phone.getString("office");
HashMap<String, String> contact = new HashMap<>();
contact.put("id", id);
contact.put("name", name);
contact.put("email", email);
contact.put("mobile", mobile);
contactList.add(contact);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG)
.show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
if (pDialog.isShowing())
pDialog.dismiss();
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, contactList,
R.layout.list_item, new String[]{"name", "email",
"mobile"}, new int[]{R.id.name,
R.id.email, R.id.mobile});
lv.setAdapter(adapter);
}
}
}