《第一行代码》11.2.2确定自己位置的经纬度 为什么我的跟书上的一模一样却不显示经纬度？

Question

package com.example.administrator.locationmanager;

import android.app.Activity;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

public class MainActivity extends Activity {
private TextView positionTextView;
private LocationManager locationManager;
private String provider;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
positionTextView = (TextView) findViewById(R.id.position_text_view);
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
// 获取所有可用的位置提供器
List providerList = locationManager.getProviders(true);
if (providerList.contains(LocationManager.GPS_PROVIDER)) {
provider = LocationManager.GPS_PROVIDER;
} else if (providerList.contains(LocationManager.NETWORK_PROVIDER)) {
provider = LocationManager.NETWORK_PROVIDER;
} else {
// 当没有可用的位置提供器时，弹出Toast提示用户
Toast.makeText(this, "No location provider to use",
Toast.LENGTH_SHORT).show();
return;
}
Location location = locationManager.getLastKnownLocation(provider);
if (location != null) {
// 显示当前设备的位置信息
showLocation(location);
}
locationManager.requestLocationUpdates(provider,5000,1,locationListener);
}
protected void onDestroy() {
super.onDestroy();
if (locationManager != null) {
// 关闭程序时将监听器移除
locationManager.removeUpdates(locationListener);
}
}
LocationListener locationListener = new LocationListener() {
@Override
public void onStatusChanged(String provider, int status, Bundle
extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onLocationChanged(Location location) {
// 更新当前设备的位置信息
showLocation(location);
}
};
private void showLocation(Location location) {
String currentPosition = "latitude is " + location.getLatitude() + "\n"
+ "longitude is " + location.getLongitude();
positionTextView.setText(currentPosition);
}
}
权限代码：
<?xml version="1.0" encoding="utf-8"?>
package="com.example.administrator.locationmanager">

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

activity_main的代码
<?xml version="1.0" encoding="utf-8"?>
android:layout_width="match_parent"
android:layout_height="match_parent">
android:id="@+id/position_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

Answer 1

一是书上的代码有误，一是你的有误，跟书上的不一样，注意小细节