我正在尝试为 goofle 地图开发一个自动完成位置。但是，我在开发过程中遇到了一些错误。我不知道错误的原因是什么。
下面是我的代码。
public class MainActivity extends Activity {
/** Called when the activity is first created. */
ArrayAdapter<String> adapter;
AutoCompleteTextView textView;
Object[] arg0 = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
adapter = new ArrayAdapter<String>(this, R.layout.item_list);
textView = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView1);
adapter.setNotifyOnChange(true);
textView.setAdapter(adapter);
textView.addTextChangedListener(new TextWatcher() {
public void onTextChanged(CharSequence s, int start, int before,
int count) {
if (count % 3 == 1) {
adapter.clear();
// GetPlaces task = new GetPlaces();
// now pass the argument in the textview to the task
new GetPlaces().execute(textView.getText().toString());
}
}
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
}
public void afterTextChanged(Editable s) {
}
});
}
class GetPlaces extends AsyncTask<String, Void, ArrayList<String>> {
@Override
// three dots is java for an array of strings
protected ArrayList<String> doInBackground(String... args) {
Log.d("gottaGo", "doInBackground");
ArrayList<String> predictionsArr = new ArrayList<String>();
try {
URL googlePlaces = new URL(
// URLEncoder.encode(url,"UTF-8");
"https://maps.googleapis.com/maps/api/place/autocomplete/json?input="
+ URLEncoder.encode(arg0[0].toString(), "UTF-8")
+ "&types=geocode&language=en&sensor=true&key=<API-key here>");
URLConnection tc = googlePlaces.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(
tc.getInputStream()));
String line;
StringBuffer sb = new StringBuffer();
// take Google's legible JSON and turn it into one big
// string.
while ((line = in.readLine()) != null) {
sb.append(line);
}
// turn that string into a JSON object
JSONObject predictions = new JSONObject(sb.toString());
// now get the JSON array that's inside that object
JSONArray ja = new JSONArray(
predictions.getString("predictions"));
for (int i = 0; i < ja.length(); i++) {
JSONObject jo = (JSONObject) ja.get(i);
// add each entry to our array
predictionsArr.add(jo.getString("description"));
}
} catch (IOException e) {
Log.e("YourApp", "GetPlaces : doInBackground", e);
} catch (JSONException e) {
Log.e("YourApp", "GetPlaces : doInBackground", e);
}
return predictionsArr;
}
// then our post
@Override
protected void onPostExecute(ArrayList<String> result) {
Log.d("YourApp", "onPostExecute : " + result.size());
// update the adapter
adapter = new ArrayAdapter<String>(getBaseContext(),
R.layout.item_list);
adapter.setNotifyOnChange(true);
// attach the adapter to textview
textView.setAdapter(adapter);
for (String string : result) {
Log.d("YourApp", "onPostExecute : result = " + string);
adapter.add(string);
adapter.notifyDataSetChanged();
}
Log.d("YourApp",
"onPostExecute : autoCompleteAdapter" + adapter.getCount());
}
这是 logcat 错误：
10-24 15:10:54.609: E/AndroidRuntime(14346): FATAL EXCEPTION: AsyncTask #1
10-24 15:10:54.609: E/AndroidRuntime(14346): java.lang.RuntimeException: An error occured while executing doInBackground()
10-24 15:10:54.609: E/AndroidRuntime(14346): at android.os.AsyncTask$3.done(AsyncTask.java:278)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
10-24 15:10:54.609: E/AndroidRuntime(14346): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.lang.Thread.run(Thread.java:856)
10-24 15:10:54.609: E/AndroidRuntime(14346): Caused by: java.lang.NullPointerException
10-24 15:10:54.609: E/AndroidRuntime(14346): at com.test.main.MainActivity$GetPlaces.doInBackground(MainActivity.java:76)
10-24 15:10:54.609: E/AndroidRuntime(14346): at com.test.main.MainActivity$GetPlaces.doInBackground(MainActivity.java:1)
10-24 15:10:54.609: E/AndroidRuntime(14346): at android.os.AsyncTask$2.call(AsyncTask.java:264)
10-24 15:10:54.609: E/AndroidRuntime(14346): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)