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问题描述
几天前，我问了一个类似的问题，关于如何从AngularJS中的JSON文件中读取所需的数据，但是我要在android中的java中完成此工作，因此在读取和记录JSON文件时遇到了这样的问题， :
{
"results" : [
{
"address_components" : [
{
"long_name" : "277",
"short_name" : "277",
"types" : [ "street_number" ]
},
{
"long_name" : "Bedford Avenue",
"short_name" : "Bedford Ave",
"types" : [ "route" ]
},
{
"long_name" : "Williamsburg",
"short_name" : "Williamsburg",
"types" : [ "neighborhood", "political" ]
},
{
"long_name" : "Brooklyn",
"short_name" : "Brooklyn",
"types" : [ "sublocality_level_1", "sublocality", "political" ]
},
{
"long_name" : "Kings County",
"short_name" : "Kings County",
"types" : [ "administrative_area_level_2", "political" ]
},
{
"long_name" : "New York",
"short_name" : "NY",
"types" : [ "administrative_area_level_1", "political" ]
},
{
"long_name" : "United States",
"short_name" : "US",
"types" : [ "country", "political" ]
},
{
"long_name" : "11211",
"short_name" : "11211",
"types" : [ "postal_code" ]
}
],
"formatted_address" : "277 Bedford Ave, Brooklyn, NY 11211, USA",
"geometry" : {
"location" : {
"lat" : 40.714232,
"lng" : -73.9612889
},
"location_type" : "ROOFTOP",
"viewport" : {
"northeast" : {
"lat" : 40.7155809802915,
"lng" : -73.9599399197085
},
"southwest" : {
"lat" : 40.7128830197085,
"lng" : -73.96263788029151
}
}
},
"place_id" : "ChIJd8BlQ2BZwokRAFUEcm_qrcA",
"types" : [ "street_address" ]
},
],
"status" : "OK"
}
我知道在Java/android中，我们有2种类型(JSON数组和JSON对象，它们用[和{)表示.我只需要城市名称，而不是所有这些数据.我怎么能记录只想要的对象行.
我尝试了这段代码，但这没用:
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
String data = "";
while ((line = reader.readLine()) != null) {
buffer.append(line+"\n");
Log.d("Response: ", "> " + line);
try {
JSONObject jsonRootObject = new JSONObject(line);
JSONArray jsonArray = jsonRootObject.optJSONArray("results");
for(int i=0; i < jsonArray.length(); i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
String name = jsonObject.optString("formatted_address").toString();
data = name;
}
} catch (JSONException e) {e.printStackTrace();}
}
return data.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
-------------- 编辑:我使用了这段代码:
JSONObject jsonRootObject = new JSONObject(newData);
JSONArray jsonArray = jsonRootObject.optJSONArray("results");
for(int i=0; i <=1 ; i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
data = jsonObject.getString("address_components");
}
现在我有另一个像这样的json字符串:
[
{
"long_name" : "277",
"short_name" : "277",
"types" : [ "street_number" ]
},
{
"long_name" : "Bedford Avenue",
"short_name" : "Bedford Ave",
"types" : [ "route" ]
},
{
"long_name" : "Williamsburg",
"short_name" : "Williamsburg",
"types" : [ "neighborhood", "political" ]
},
{
"long_name" : "Brooklyn",
"short_name" : "Brooklyn",
"types" : [ "sublocality_level_1", "sublocality", "political" ]
}]
我如何访问object(n)的"long_name"键的值?
解决方案
将try块更改为
while ((line = reader.readLine()) != null) {
buffer.append(line+"\n");
}
Log.d("Response: ", "> " + line);
try {
JSONObject jsonRootObject = new JSONObject(line);
JSONArray jsonArray = jsonRootObject.optJSONArray("results");
for(int i=0; i < jsonArray.length(); i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
data = jsonObject.getString("formatted_address")
}
} catch (JSONException e) {e.printStackTrace();}
return data;
现在您将拥有有效的字符串到JSONObject的转换，因为以前您是在while循环中解析了不完整的字符串，而这不是有效的json.
I asked a similar question few days ago about how i could read just wanted data from JSON file in AngularJS, but i gonna do this job in java in android, so I have a problem in reading and logging JSON file like this,:
{
"results" : [
{
"address_components" : [
{
"long_name" : "277",
"short_name" : "277",
"types" : [ "street_number" ]
},
{
"long_name" : "Bedford Avenue",
"short_name" : "Bedford Ave",
"types" : [ "route" ]
},
{
"long_name" : "Williamsburg",
"short_name" : "Williamsburg",
"types" : [ "neighborhood", "political" ]
},
{
"long_name" : "Brooklyn",
"short_name" : "Brooklyn",
"types" : [ "sublocality_level_1", "sublocality", "political" ]
},
{
"long_name" : "Kings County",
"short_name" : "Kings County",
"types" : [ "administrative_area_level_2", "political" ]
},
{
"long_name" : "New York",
"short_name" : "NY",
"types" : [ "administrative_area_level_1", "political" ]
},
{
"long_name" : "United States",
"short_name" : "US",
"types" : [ "country", "political" ]
},
{
"long_name" : "11211",
"short_name" : "11211",
"types" : [ "postal_code" ]
}
],
"formatted_address" : "277 Bedford Ave, Brooklyn, NY 11211, USA",
"geometry" : {
"location" : {
"lat" : 40.714232,
"lng" : -73.9612889
},
"location_type" : "ROOFTOP",
"viewport" : {
"northeast" : {
"lat" : 40.7155809802915,
"lng" : -73.9599399197085
},
"southwest" : {
"lat" : 40.7128830197085,
"lng" : -73.96263788029151
}
}
},
"place_id" : "ChIJd8BlQ2BZwokRAFUEcm_qrcA",
"types" : [ "street_address" ]
},
],
"status" : "OK"
}
I know in Java/android we have 2 types (JSON array and JSON object and these represents with [ and { ). I just need the name of city, not all of these data. How could I log just wanted object row.
I tried this code but that doesn't work:
protected String doInBackground(String... params) {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(params[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream stream = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer buffer = new StringBuffer();
String line = "";
String data = "";
while ((line = reader.readLine()) != null) {
buffer.append(line+"\n");
Log.d("Response: ", "> " + line);
try {
JSONObject jsonRootObject = new JSONObject(line);
JSONArray jsonArray = jsonRootObject.optJSONArray("results");
for(int i=0; i < jsonArray.length(); i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
String name = jsonObject.optString("formatted_address").toString();
data = name;
}
} catch (JSONException e) {e.printStackTrace();}
}
return data.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
try {
if (reader != null) {
reader.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
-------------- Edit:i used this code:
JSONObject jsonRootObject = new JSONObject(newData);
JSONArray jsonArray = jsonRootObject.optJSONArray("results");
for(int i=0; i <=1 ; i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
data = jsonObject.getString("address_components");
}
and now i have another json string like this:
[
{
"long_name" : "277",
"short_name" : "277",
"types" : [ "street_number" ]
},
{
"long_name" : "Bedford Avenue",
"short_name" : "Bedford Ave",
"types" : [ "route" ]
},
{
"long_name" : "Williamsburg",
"short_name" : "Williamsburg",
"types" : [ "neighborhood", "political" ]
},
{
"long_name" : "Brooklyn",
"short_name" : "Brooklyn",
"types" : [ "sublocality_level_1", "sublocality", "political" ]
}]
how i can access to value of the "long_name" key of object(n) ?
解决方案
change your try block to
while ((line = reader.readLine()) != null) {
buffer.append(line+"\n");
}
Log.d("Response: ", "> " + line);
try {
JSONObject jsonRootObject = new JSONObject(line);
JSONArray jsonArray = jsonRootObject.optJSONArray("results");
for(int i=0; i < jsonArray.length(); i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
data = jsonObject.getString("formatted_address")
}
} catch (JSONException e) {e.printStackTrace();}
return data;
Now you will have valid string to JSONObject conversion since previously you parsing incomplete string in while loop which isnt valid json.
这篇关于如何在Java&中从JSON读取所需的数据安卓的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！