嗨,我正在尝试从http://developer.android.com/reference/android/location/Location.html#distanceBetween(double,double,double,double,float [])实现distanceBetween方法。
我是编码的新手,所以我相信我正在使它比应有的难度更大,但是我不确定为什么。我正在尝试获取该JSON对象并从FIeld1(callsign),Field2(frequency),Field21(latitude),Field24(latitude)中获取信息。
然后,我想运行distanceBetween来确定它是否在例如350 KM的半径内。有人可以帮我一些提示或代码吗?谢谢!
这是我的更新MainActivity.java
package com.dredaydesigns.radiostationfinder;
import android.R;
import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.location.Location;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationServices;
import com.squareup.okhttp.Call;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import butterknife.Bind;
import butterknife.ButterKnife;
public class MainActivity extends Activity implements GoogleApiClient.ConnectionCallbacks {
public static final String TAG = MainActivity.class.getSimpleName();
private RadioData mRadioData;
private GoogleApiClient mGoogleApiClient;
private Location mLastLocation;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list_content);
ButterKnife.bind(this);
Location locationUserLatitude = mLastLocation;
Location locationUserLongitude = mLastLocation;
Location latitudeStation;
Location longitudeStation;
RadioData mRadioData = new RadioData();
OkHttpClient client = new OkHttpClient();
String radioFinderURL = "http://dredaycreative.com/json/radioData.json";
Request request = new Request.Builder()
.url(radioFinderURL)
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Request request, IOException e) {
}
@Override
public void onResponse(Response response) throws IOException {
try {
String jsonData = response.body().string();
Log.v(TAG, jsonData);
if (response.isSuccessful()) {
getCurrentRadioData(jsonData);
}
} catch (IOException e) {
Log.e(TAG, "Exception Caught: ", e);
} catch (JSONException e) {
Log.e(TAG, "Exception Caught:", e);
}
}
});
}
private List getCurrentRadioData(String jsonData) throws JSONException{
List radioData = new ArrayList<String>();
Object obj=JSONValue.parse(jsonData);
JSONArray data;
data = (JSONArray)obj;
for (int i=0; i<data.length(); i++) {
JSONObject jasonObj = data.getJSONObject(i);
if (Location.distanceBetween() <= 350) {
float[] results = new float[3];
Location.distanceBetween(mLastLocation.getLatitude(), mLastLocation.getLongitude(), latitudeStation, longitudeStation, results);
float distance = results[0];
JSONObject callsign = jasonObj.getJSONObject("FIELD1");
radioData.add(callsign);
JSONObject frequency = jasonObj.getJSONObject("FIELD2");
radioData.add(frequency);
double latitudeStations = jasonObj.getDouble("FIELD21");
radioData.add(latitudeStations);
double longitudeStations = jasonObj.getDouble("FIELD24");
radioData.add(longitudeStations);
} else {
}
}
return radioData;
}
private void updateDisplay() {
mLatitudeLabel.setText(String.valueOf(mLastLocation.getLatitude()));
mLongitudeLabel.setText(String.valueOf(mLastLocation.getLongitude()));
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener((GoogleApiClient.OnConnectionFailedListener) this)
.addApi(LocationServices.API)
.build();
}
@Override
public void onConnected(Bundle bundle) {
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
mGoogleApiClient);
if (mLastLocation != null) {
// mLatitudeLabel.setText(String.valueOf(mLastLocation.getLatitude()+ ""));
// mLongitudeLabel.setText(String.valueOf(mLastLocation.getLongitude()+""));
}
}
@Override
public void onConnectionSuspended(int i) {
}
}
这是我在github上从某人那里抢到的jsonValue.java
package com.dredaydesigns.radiostationfinder;
/*
* $Id: JSONValue.java,v 1.1 2006/04/15 14:37:04 platform Exp $
* Created on 2006-4-15
*/
import org.json.simple.parser.JSONParser;
import java.io.Reader;
import java.io.StringReader;
/**
* @author FangYidong<[email protected]>
*/
public class JSONValue {
/**
* parse into java object from input source.
* @param in
* @return instance of : JSONObject,JSONArray,String,Boolean,Long,Double or null
*/
public static Object parse(Reader in){
try{
JSONParser parser=new JSONParser();
return parser.parse(in);
}
catch(Exception e){
return null;
}
}
public static Object parse(String s){
StringReader in=new StringReader(s);
return parse(in);
}
}
这是XML
<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"
android:background="#ffffed">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Text"
android:id="@+id/latitudeLabel"
android:layout_alignParentTop="true"
android:layout_marginTop="49dp"
android:layout_centerHorizontal="true"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Text"
android:id="@+id/longitudeLabel"
android:layout_below="@+id/latitudeLabel"
android:layout_marginTop="72dp"
android:layout_centerHorizontal="true"/>
</RelativeLayout>
这就是Radioter.java的获取者和设置者...我从teamtreehouse中学到的东西把这个项目自己拼凑在一起,如果它很俗气,我深表歉意。
package com.dredaydesigns.radiostationfinder;
/**
* Created by Andreas on 8/10/2015.
*/
public class RadioData {
public String getCallSign() {
return mCallsign;
}
public void setCallSign(String callsign) {
mCallsign = callsign;
}
public double getFrequency() {
return mFrequency;
}
public void setFrequency(double frequency) {
mFrequency = frequency;
}
public int getChannel() {
return mChannel;
}
public void setChannel(int channel) {
mChannel = channel;
}
public double getLatitude() {
return mLatitude;
}
public void setLatitude(double latitude) {
mLatitude = latitude;
}
public double getLongitude() {
return mLongitude;
}
public void setLongitude(double longitude) {
mLongitude = longitude;
}
private String mCallsign;
private double mFrequency;
private int mChannel;
private double mLatitude;
private double mLongitude;
}
在用户提出建议后,我现在将MainActivity代码的这一部分更改为以下内容,但是在某些地方似乎还是错误的,我需要帮助,谢谢!我的gradle没问题,但是我无法让genymotion正常工作,所以我不知道什么有效!如果这部分工作正常,下一步对我来说就是向用户显示localRadioData:D
:
private List getCurrentRadioData() throws JSONException{
List radioData = new ArrayList<String>();
List localRadioData = new ArrayList();
Object obj=JSONValue.parse(String.valueOf(radioData));
JSONArray data;
data = (JSONArray)obj;
float[] results = new float[3];
double latitudeStation = 0;
double longitudeStation = 0;
for (int i=0; i<data.length(); i++) {
JSONObject jasonObj = data.getJSONObject(i);
double latitudeStations = jasonObj.getDouble("FIELD21");
radioData.add(latitudeStations);
double longitudeStations = jasonObj.getDouble("FIELD24");
radioData.add(longitudeStations);
Location.distanceBetween(mLastLocation.getLatitude(), mLastLocation.getLongitude(), latitudeStation, longitudeStation, results);
float distance = results[0];
distance = Math.round(distance);
if ((distance) > 350) {
JSONObject callsign = jasonObj.getJSONObject("FIELD1");
localRadioData.add(callsign);
JSONObject frequency = jasonObj.getJSONObject("FIELD2");
localRadioData.add(frequency);
} else {
radioData.add(getCurrentRadioData());
}
}
return localRadioData;
}
最佳答案
distanceBetween是Location类的静态函数,意味着您可以通过执行以下操作简单地调用它:
float[] results = new float[3];
Location.distanceBetween(startLat, startLong, endLat, endLong, results);
float distance = results[0];
关于如何在代码中实现它,它看起来可能像这样:
float[] results = new float[3];
Location.distanceBetween(mLastLocation.getLatitude(), mLastLocation.getLongitude(), latitudeStation, longitudeStation, results);
float distance = results[0];
我希望这会有所帮助:)
关于java - 如何修复Android的distanceBetween方法语法?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/32597669/