Question

我正在为我的Evo 4G上的GPS定位做一个示例应用程序。这最终将被集成到应用程序中以供时间卡使用。但是，它强行关闭。我没有任何想法为什么......有什么帮助吗？

package com.Rick.GPS;

import android.app.Activity;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;

public class Main extends Activity implements LocationListener {

/* this class implements LocationListener, which listens for both
 * changes in the location of the device and changes in the status
 * of the GPS system.
 * */

static final String tag = "Main"; // for Log

TextView txtInfo;
LocationManager lm;
StringBuilder sb;
int noOfFixes = 0;

/** Called when the activity is first created. */

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    /* get TextView to display the GPS data */
    txtInfo = (TextView) findViewById(R.id.Text1);

    /* the location manager is the most vital part it allows access
     * to location and GPS status services */
    lm = (LocationManager) getSystemService(LOCATION_SERVICE);
}


protected void onResume() {
    /*
     * onResume is is always called after onStart, even if the app hasn't been
     * paused
     *
     * add location listener and request updates every 1000ms or 10m
     */
    lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 10f, this);
    super.onResume();
}


protected void onPause() {
    /* GPS, as it turns out, consumes battery like crazy */
    lm.removeUpdates(this);
    super.onPause();
}


public void onLocationChanged(Location location) {
    Log.v(tag, "Location Changed");

    sb = new StringBuilder(512);

    noOfFixes++;

    /* display some of the data in the TextView */

    sb.append("No. of Fixes: ");
    sb.append(noOfFixes);
    sb.append('\n');
    sb.append('\n');

    sb.append("Londitude: ");
    sb.append(location.getLongitude());
    sb.append('\n');

    sb.append("Latitude: ");
    sb.append(location.getLatitude());
    sb.append('\n');

    sb.append("Altitiude: ");
    sb.append(location.getAltitude());
    sb.append('\n');

    sb.append("Accuracy: ");
    sb.append(location.getAccuracy());
    sb.append('\n');

    sb.append("Timestamp: ");
    sb.append(location.getTime());
    sb.append('\n');

    txtInfo.setText(sb.toString());
}


public void onProviderDisabled(String provider) {
    /* this is called if/when the GPS is disabled in settings */
    Log.v(tag, "Disabled");

    /* bring up the GPS settings */
    Intent intent = new Intent(
            android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
    startActivity(intent);
}


public void onProviderEnabled(String provider) {
    Log.v(tag, "Enabled");
    Toast.makeText(this, "GPS Enabled", Toast.LENGTH_SHORT).show();

}


public void onStatusChanged(String provider, int status, Bundle extras) {
    /* This is called when the GPS status alters */
    switch (status) {
    case LocationProvider.OUT_OF_SERVICE:
        Log.v(tag, "Status Changed: Out of Service");
        Toast.makeText(this, "Status Changed: Out of Service",
                Toast.LENGTH_SHORT).show();
        break;
    case LocationProvider.TEMPORARILY_UNAVAILABLE:
        Log.v(tag, "Status Changed: Temporarily Unavailable");
        Toast.makeText(this, "Status Changed: Temporarily Unavailable",
                Toast.LENGTH_SHORT).show();
        break;
    case LocationProvider.AVAILABLE:
        Log.v(tag, "Status Changed: Available");
        Toast.makeText(this, "Status Changed: Available",
                Toast.LENGTH_SHORT).show();
        break;
    }
}


protected void onStop() {
    /* may as well just finish since saving the state is not important for this toy app */
    finish();
    super.onStop();
}
}

这是布局文件......

<TextView
    android:id="@+id/Text1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello" />

这是清单......

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.Rick.GPS"
android:versionCode="1"
android:versionName="1.0" >

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-sdk android:minSdkVersion="10" />

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
    <activity
        android:label="@string/app_name"
        android:name=".GPSActivity" >
        <intent-filter >
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

</manifest>

感谢您提供任何帮助......

Answer 1

我可以发现两个错误：

您需要拨打setContentView(R.layout.main);，不要发表评论。否则，你会在下一行得到一个NullPointerException。
在XML中，您将Text1定义为EditText，但是在您的课程中，您尝试将其强制转换为TextView并获得类强制转换异常。在XML或java文件中更改它。根据您在代码中的注释，您应该在XML中更改它。

Answer 2

 protected void onPause() {     /* GPS, as it turns out, consumes battery like crazy */     lm.removeUpdates(this);     super.onPause(); }

还注释了setContentView代码...

Answer 3

onLocationChange是否可以访问textField？无论如何，我认为设计这个应用程序的更好方法是在单独的thead中进行位置监听，例如使用handler来更新UI线程。此方法还消除了位置修复可能会阻止UI线程的风险。

Answer 4

你在onPause方法的主体中调用super.onResume。

如何阻止我的申请强制关闭？

4 个答案: