我遇到onResume（）的问题，我的应用程序在对intent处理程序的函数调用期间崩溃。当我的app优先使用enableForegroundDispath（）方法读取NFC标签时，它也会崩溃。我已将所有NFC意图过滤器和权限添加到清单中。如果我在onResume（）中注释掉最后两个方法，应用程序运行完美......不确定是什么问题，但是真的很感激任何帮助！ MainActivity如下。
package com.example.final_project;
import java.util.Locale;
import android.app.Activity;
import android.app.ActivityOptions;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.IntentFilter.MalformedMimeTypeException;
import android.content.SharedPreferences;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.os.Bundle;
import android.speech.tts.TextToSpeech;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.Toast;
public class MainActivity extends Activity implements TextToSpeech.OnInitListener {
Button B1,B2,foodButton;
static EditText Text1;
static Context context;
String Text;
String Preference;
String NearMe= "+near+me";
Double Latitude, Longitude;
ImageView TV;
Button FavoriteButton;
View FavoriteView;
TextToSpeech tts;
Intent Gpsintent;
ProgressBar progress;
//NFC Stuff
private static final String TAG = "NFCTag";
private static final String APP_MIME_TYPE = "application/edu.villanova.ece5480.nfctag";
private static final String APP_LAUNCH_MIME_TYPE = APP_MIME_TYPE + ".launch";
NfcAdapter nfc = null;
Tag tag = null;
PendingIntent intentPending = null;
IntentFilter[] readFilters = null;
IntentFilter[] writeFilters = null;
public static String MY_PREFS = "edu.villanova.ece5480.my_prefs";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context=MainActivity.this;
tts = new TextToSpeech(this, this);
Text1=(EditText)findViewById(R.id.editText1);
TV=(ImageView)findViewById(R.id.imageView2);
progress = (ProgressBar)findViewById(R.id.progressBar1);
//NFC
// get an instance of the device NfcAdapter
nfc = NfcAdapter.getDefaultAdapter(this);
if (nfc == null) {
// let user know that their device does not support NFC then exit
Toast.makeText(this, "Device does not support NFC.", Toast.LENGTH_LONG).show();
finish();
return;
}
// handle foreground NFC scanning in this activity by creating a pending intent
// with FLAG_ACTIVITY_SINGLE_TOP flag so each new scan is not added to the Back Stack
intentPending = PendingIntent.getActivity(this, 0,
new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
// intents for reading NDEF tags action
IntentFilter appRead = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try { appRead.addDataType(APP_MIME_TYPE); }
catch (MalformedMimeTypeException e) { Log.e(TAG, "MalforedMimeTypeException:" + e.toString()); }
IntentFilter launchRead = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try { launchRead.addDataType(APP_LAUNCH_MIME_TYPE); }
catch (MalformedMimeTypeException e) { Log.e(TAG, "MalforedMimeTypeException:" + e.toString()); }
readFilters = new IntentFilter[] { appRead, launchRead };
// intent for writing NDEF tag action - read any tag (could check for formatable)
IntentFilter appWrite = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
writeFilters = new IntentFilter[] { appWrite };
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
return true;
}
@Override
public void onInit(int status) {
if (status == TextToSpeech.SUCCESS) {
int result = tts.setLanguage(Locale.US);
}
else {
Log.e("TTS", "Initilization Failed!");
}
}
@Override
protected void onResume() {
super.onResume();
if (!nfc.isEnabled()){
// NFC is not enabled, launch wireless settings intent for user to enable
startActivity(new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS));
Toast.makeText(this, "Enable NFC", Toast.LENGTH_LONG).show();
}
// tag received when app is not running and/or foreground dispatch is not enabled
handleIntent(this.getIntent());
/*
// enable priority for activity to detect scanned tags
nfc.enableForegroundDispatch(this, intentPending, readFilters, null); */
}
@Override
protected void onPause() {
super.onPause();
// disable priority for activity to detect scanned tags
nfc.disableForegroundDispatch(this);
}
@Override
protected void onNewIntent(Intent intent) {
Log.d(TAG, "onNewIntent() triggered");
// tag received when app set launchMode to “singleTask� and/or foreground dispatch is enabled
handleIntent(intent);
}
@Override
protected void onDestroy()
{
super.onDestroy();
}
public void GpsClick(View view) throws InterruptedException{
progress.setVisibility(0);
LocationManager mlocManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
if(!mlocManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
LocationListener mlocListener = new MyLocationListener();
mlocManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 10000, mlocListener);
}
public void FindPartyClick(View view){
Preference=Text1.getText().toString();
SharedPreferences prefs = getSharedPreferences(MY_PREFS, Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = prefs.edit();
editor.putString(Preference, Preference);
editor.commit();
Intent intent = new Intent(MainActivity.this, SearchClass.class);
String Address=Text1.getText().toString().replace(' ', '+');
if((Address.length()!=5 && Address.matches("\\d+")) || Address.length()<2)
Toast.makeText( getApplicationContext(),"Zip Code must be 5 digits" , Toast.LENGTH_SHORT ).show();
else{
String text = MainActivity.Text1.getText().toString();
int i;
for(i=0;i<10;i++){
text=text.replace(String.valueOf(i),String.valueOf(i) + ' ');
}
//tts.speak(text,TextToSpeech.QUEUE_FLUSH,null);
tts.speak("What's The Move",TextToSpeech.QUEUE_FLUSH,null);
intent.putExtra("message", Address);
Bundle bndlanimation = ActivityOptions.makeCustomAnimation(getApplicationContext(), R.anim.animation,R.anim.animation2).toBundle();
startActivity(intent, bndlanimation);
}
}
/* Class My Location Listener */
public class MyLocationListener implements LocationListener{
@Override
public void onLocationChanged(Location loc){
Latitude=loc.getLatitude();
Longitude=loc.getLongitude();
//setGPS(loc.getLatitude(),loc.getLongitude());
Intent Gpsintent = new Intent(MainActivity.this, SearchClass.class);
Gpsintent.putExtra("latitude", Latitude);
Gpsintent.putExtra("longitude",Longitude);
Gpsintent.putExtra("message", NearMe);
//tts.speak("Finding Current Location",TextToSpeech.QUEUE_FLUSH,null);
progress.setVisibility(2);
tts.speak("What's The Move",TextToSpeech.QUEUE_FLUSH,null);
Bundle bndlanimation = ActivityOptions.makeCustomAnimation(getApplicationContext(), R.anim.animation,R.anim.animation2).toBundle();
startActivity(Gpsintent, bndlanimation);
}
public String setGPS(double Lat, double Long){
Latitude=Lat;
Longitude=Long;
Text = "My current location is: " + "Latitude = " + Lat + "Longitude = " + Long;
return Text;
}
@Override
public void onProviderDisabled(String provider)
{
Toast.makeText( getApplicationContext(),"Gps Disabled" , Toast.LENGTH_SHORT ).show();
}
@Override
public void onProviderEnabled(String provider)
{
Toast.makeText( getApplicationContext(), "Gps Enabled", Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
}/* End of Class MyLocationListener */
protected void handleIntent(Intent intent){
String action = intent.getAction();
if(action.equals(NfcAdapter.ACTION_NDEF_DISCOVERED)){
intent = new Intent(MainActivity.this, NFCClass.class);
startActivity(intent);
}
}
}/* End of Main Activity */
logcat的
12-10 20:52:07.871: E/AndroidRuntime(11113): FATAL EXCEPTION: main
12-10 20:52:07.871: E/AndroidRuntime(11113): java.lang.RuntimeException: Unable to resume activity {com.example.final_project/com.example.final_project.MainActivity}: java.lang.NullPointerException
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2639)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2667)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2140)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.ActivityThread.access$700(ActivityThread.java:143)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.os.Handler.dispatchMessage(Handler.java:99)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.os.Looper.loop(Looper.java:137)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.ActivityThread.main(ActivityThread.java:4950)
12-10 20:52:07.871: E/AndroidRuntime(11113): at java.lang.reflect.Method.invokeNative(Native Method)
12-10 20:52:07.871: E/AndroidRuntime(11113): at java.lang.reflect.Method.invoke(Method.java:511)
12-10 20:52:07.871: E/AndroidRuntime(11113): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1004)
12-10 20:52:07.871: E/AndroidRuntime(11113): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:771)
12-10 20:52:07.871: E/AndroidRuntime(11113): at dalvik.system.NativeStart.main(Native Method)
12-10 20:52:07.871: E/AndroidRuntime(11113): Caused by: java.lang.NullPointerException
12-10 20:52:07.871: E/AndroidRuntime(11113): at com.example.final_project.MainActivity.handleIntent(MainActivity.java:152)
12-10 20:52:07.871: E/AndroidRuntime(11113): at com.example.final_project.MainActivity.onResume(MainActivity.java:143)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1199)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.Activity.performResume(Activity.java:5253)
12-10 20:52:07.871: E/AndroidRuntime(11113): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2629)
12-10 20:52:07.871: E/AndroidRuntime(11113): ... 12 more
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