我正在尝试按照标题所说的去做，即在 android 上创建一个带有谷歌距离矩阵的应用程序，并带有自动完成功能。到目前为止，我自己研究和研究书籍，很难想出代码，我终于在这里接触到了。到目前为止，我已经去了
https://developers.google.com/maps/documentation/distancematrix/#Introduction
和谷歌方向文件
http://www.claytical.com/blog/android-dynamic-autocompletion-using-google-places-api http://www.stackoverflow.com/questions/9142885/geocoder-autocomplete-in-android http:// www.stackoverflow.com/questions/6456090/android-google-map-finding-distance/6456161#6456161
所有这些链接并没有真正帮助我理解它，我确实理解请求 API 地址并返回 JSON 的概念，我必须“解析”JSON 并提取必要的信息，这就是我的情况的距离。但我没有得到的是如何创建一个自动完成，该自动完成具有来自谷歌地图距离矩阵的建议，以及如何相应地发送起点和目的地。这真的很令人沮丧，这就是我从 Claytical.com 获得的。
这是main.java
package com.example.autocomplete;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.ArrayList;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
public class Main extends Activity {
/** Called when the activity is first created. */
public ArrayAdapter<String> adapter;
public AutoCompleteTextView textview;
public Object s;
class GetPlaces extends AsyncTask<String, Void, ArrayList<String>>
{
public ArrayAdapter<String> adapter;
public AutoCompleteTextView textview;
Object s;
@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(s.toString(), "UTF-8") +"&types=geocode&language=en&sensor=true&key=<yourapikeygoeshere>");
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
ArrayAdapter<String> 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());
}
private Context getBaseContext() {
// TODO Auto-generated method stub
return null;
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.item_list);
final AutoCompleteTextView 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
task.execute(textView.getText().toString());
}
}
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub
}
public void afterTextChanged(Editable s) {
}
});
}
}
和我的 main.xml
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#dddddd">
<AutoCompleteTextView
android:id="@+id/autoCompleteTextView1"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_marginTop="10dp" >
<requestFocus></requestFocus>
</AutoCompleteTextView>
最后，这里是请求的 LOGCAT。
05-14 17:41:38.163: E/Trace(1390): error opening trace file: No such file or directory (2)
05-14 17:41:39.323: D/gralloc_goldfish(1390): Emulator without GPU emulation detected.
05-14 17:41:45.284: D/gottaGo(1390): doInBackground
05-14 17:41:45.296: W/dalvikvm(1390): threadid=11: thread exiting with uncaught exception (group=0x40a13300)
05-14 17:41:45.314: E/AndroidRuntime(1390): FATAL EXCEPTION: AsyncTask #1
05-14 17:41:45.314: E/AndroidRuntime(1390): java.lang.RuntimeException: An error occured while executing doInBackground()
05-14 17:41:45.314: E/AndroidRuntime(1390): at android.os.AsyncTask$3.done(AsyncTask.java:299)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
05-14 17:41:45.314: E/AndroidRuntime(1390): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.lang.Thread.run(Thread.java:856)
05-14 17:41:45.314: E/AndroidRuntime(1390): Caused by: java.lang.NullPointerException
05-14 17:41:45.314: E/AndroidRuntime(1390): at com.example.autocomplete.Main$GetPlaces.doInBackground(Main.java:54)
05-14 17:41:45.314: E/AndroidRuntime(1390): at com.example.autocomplete.Main$GetPlaces.doInBackground(Main.java:1)
05-14 17:41:45.314: E/AndroidRuntime(1390): at android.os.AsyncTask$2.call(AsyncTask.java:287)
05-14 17:41:45.314: E/AndroidRuntime(1390): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
05-14 17:41:45.314: E/AndroidRuntime(1390): ... 5 more
05-14 17:41:47.584: I/Choreographer(1390): Skipped 31 frames! The application may be doing too much work on its main thread.
05-14 17:41:47.904: I/Process(1390): Sending signal. PID: 1390 SIG: 9
它启动得很好，它会显示自动完成文本视图，但只要我输入一个字母，它就会崩溃。感谢您阅读本文并提前感谢您的帮助！