Tuesday, August 7, 2012

Get address from location name, using Geocoder

android.location.Geocoder is a class for handling geocoding and reverse geocoding. Geocoding is the process of transforming a street address or other description of a location into a (latitude, longitude) coordinate. Reverse geocoding is the process of transforming a (latitude, longitude) coordinate into a (partial) address. The amount of detail in a reverse geocoded location description may vary. The Geocoder class requires a backend service that is not included in the core android framework.

The Geocoder query methods will return an empty list if there no backend service in the platform. Use the isPresent() method to determine whether a Geocoder implementation exists.

The method getFromLocationName() returns an array of Addresses that are known to describe the named location.



package com.AndroidgetFromLocationName;

import java.io.IOException;
import java.util.List;

import android.app.Activity;
import android.location.Address;
import android.location.Geocoder;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class AndroidgetFromLocationNameActivity extends Activity {

EditText searchText;
Button searchButton;
TextView listResult;

Geocoder myGeocoder;
final static int MAX_RESULT = 5;
//final static String DEFAULT_SEARCH = "1600 Amphitheatre Parkway Mountain View";
//final static String DEFAULT_SEARCH = "Times Square";
final static String DEFAULT_SEARCH = "蘋果";

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    searchText = (EditText)findViewById(R.id.searchtext);
    searchText.setText(DEFAULT_SEARCH);
 searchButton = (Button)findViewById(R.id.searchbutton);
 listResult = (TextView)findViewById(R.id.result);

 searchButton.setOnClickListener(searchButtonOnClickListener);

 myGeocoder = new Geocoder(this);

 //for API Level 9 or higher
 if (!Geocoder.isPresent()){
  Toast.makeText(AndroidgetFromLocationNameActivity.this,
  "Sorry! Geocoder service not Present.",
  Toast.LENGTH_LONG).show();
 }
}

Button.OnClickListener searchButtonOnClickListener
= new Button.OnClickListener(){

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
String searchString = searchText.getText().toString();
searchFromLocationName(searchString);
}};

private void searchFromLocationName(String name){
try {
List<Address> result
= myGeocoder.getFromLocationName(name, MAX_RESULT);

if ((result == null)||(result.isEmpty())){
 Toast.makeText(AndroidgetFromLocationNameActivity.this,
   "No matches were found or there is no backend service!",
   Toast.LENGTH_LONG).show();
}else{
 String stringResult = "";
 for (int i =0; i < result.size(); i++){
  stringResult += "i: " + i + "\n"
    + result.get(i).getAddressLine(i) + "\n"
    + "lat: " + result.get(i).getLatitude() + "\n"
    + "lon: " + result.get(i).getLongitude() + "\n";
 }
 listResult.setText(stringResult);

 Toast.makeText(AndroidgetFromLocationNameActivity.this,
   "Finished!",
   Toast.LENGTH_LONG).show();
}


} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Toast.makeText(AndroidgetFromLocationNameActivity.this,
  "The network is unavailable or any other I/O problem occurs!",
  Toast.LENGTH_LONG).show();
}
}
}


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<EditText
android:id="@+id/searchtext"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:id="@+id/searchbutton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Search"
/>
<ScrollView
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<TextView
android:id="@+id/result"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</ScrollView>
</LinearLayout>

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