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我是Android新手，正在开发我的第一个应用程序。我试图将Google表格电子表格的内容解析为Spinner。我通过使用ArrayAdapter和ArrayList成功地完成了这项工作，因为我可以在扩展Spinner时看到选项。我面临的问题是Spinner在选择某个项目时不会显示当前选定的项目。如果您尝试运行我的代码，您会看到如果您尝试点击提交Button，它会告诉您null正在被选中，因此我将问题缩小到当前选定的名称字符串未被选中。setOnItemSelectedListener未被调用？
这里是我MainActivity类别：
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
ArrayList<String> names = new ArrayList<String>();
Spinner spBusinessType;
Button btnsubmit;
ArrayAdapter<String> adapterBusinessType;
String sbusinesstype;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
spBusinessType = (Spinner) findViewById(R.id.spBussinessType);
btnsubmit=(Button)findViewById(R.id.submit);
btnsubmit.setOnClickListener(this);
new DownloadWebpageTask(new AsyncResult() {
@Override
public void onResult(JSONObject object) {
processJson(object);
}
}).execute("https://spreadsheets.google.com/tq?key=1JKU2Vt_gMNUYYALct4m9xElLdpGlQ3N4uhS9qFRzxOQ");
adapterBusinessType = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, names);
adapterBusinessType.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spBusinessType.setAdapter(adapterBusinessType);
spBusinessType.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> adapter, View v,
int position, long id) {
// On selecting a spinner item
sbusinesstype = adapter.getItemAtPosition(position).toString();
System.out.println(sbusinesstype);
// Showing selected spinner item
Toast.makeText(getApplicationContext(),
"Bussiness Type : " + sbusinesstype, Toast.LENGTH_SHORT).show();
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
});
}
@Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "You have selected " + sbusinesstype,Toast.LENGTH_SHORT).show();
}
private void processJson(JSONObject object) {
try {
JSONArray rows = object.getJSONArray("rows");
for (int r = 0; r < rows.length(); ++r) {
JSONObject row = rows.getJSONObject(r);
JSONArray columns = row.getJSONArray("c");
String name = columns.getJSONObject(0).getString("v");
names.add(name);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
的AsyncResult接口我使用的是获得来自谷歌表一JSON对象：
public interface AsyncResult
{
void onResult(JSONObject object);
}
的DownloadWebpageTask类那正在获取和解析JSON对象：
public class DownloadWebpageTask extends AsyncTask<String, Void, String> {
AsyncResult callback;
public DownloadWebpageTask(AsyncResult callback) {
this.callback = callback;
}
@Override
protected String doInBackground(String... urls) {
// params comes from the execute() call: params[0] is the url.
try {
return downloadUrl(urls[0]);
} catch (IOException e) {
return "Unable to download the requested page.";
}
}
// onPostExecute displays the results of the AsyncTask.
@Override
protected void onPostExecute(String result) {
// remove the unnecessary parts from the response and construct a JSON
int start = result.indexOf("{", result.indexOf("{") + 1);
int end = result.lastIndexOf("}");
String jsonResponse = result.substring(start, end);
try {
JSONObject table = new JSONObject(jsonResponse);
callback.onResult(table);
} catch (JSONException e) {
e.printStackTrace();
}
}
private String downloadUrl(String urlString) throws IOException {
InputStream is = null;
try {
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Starts the query
conn.connect();
int responseCode = conn.getResponseCode();
is = conn.getInputStream();
String contentAsString = convertStreamToString(is);
return contentAsString;
} finally {
if (is != null) {
is.close();
}
}
}
private String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
的activity_main布局文件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<include layout="@layout/content_main" />
</RelativeLayout>
而且我把微调的content_main布局文件：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context=".MainActivity">
tools:showIn="@layout/activity_main">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Select Business Type"
android:textColor="#000000"
android:textSize="20sp" />
<Spinner
android:id="@+id/spBussinessType"
style="@style/Base.Widget.AppCompat.Spinner.Underlined"
android:layout_width="match_parent"
android:layout_height="wrap_content"></Spinner>
<Button
android:id="@+id/submit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="10dp"
android:text="Submit"
android:textSize="15sp" />
</LinearLayout>
是什么原因造成的适配器无法检测时其中一个姓名字符串正在被选中？它可能与我如何从Google表格解析它们有关吗？
显示堆栈跟踪任何错误更换
names.add。 – HaroldSer无关：为什么不实际解析JSON而不是子串？ –