我的一项活动有一个问题，就是当我在 android Ginberbread 2.3 中测试我的应用程序时，一切都很好。但是当我在 Android ICS 或 Jeally bean 中测试我的应用程序时，它会在最后一个活动中强制关闭，这是调试中显示的错误：
08-11 18:46:55.666: E/AndroidRuntime(16107): FATAL EXCEPTION: main
08-11 18:46:55.666: E/AndroidRuntime(16107): java.lang.RuntimeException: Unable to
instantiate activity ComponentInfo{com.prueba.bibliotecaappprueba/com.prueba.bibliotecaappprueba.DetallesActivity}: java.lang.NullPointerException
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1973)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2083)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.app.ActivityThread.access$600(ActivityThread.java:134)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1233)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.os.Handler.dispatchMessage(Handler.java:99)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.os.Looper.loop(Looper.java:137)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.app.ActivityThread.main(ActivityThread.java:4697)
08-11 18:46:55.666: E/AndroidRuntime(16107): at java.lang.reflect.Method.invokeNative(Native Method)
08-11 18:46:55.666: E/AndroidRuntime(16107): at java.lang.reflect.Method.invoke(Method.java:511)
08-11 18:46:55.666: E/AndroidRuntime(16107): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
08-11 18:46:55.666: E/AndroidRuntime(16107): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
08-11 18:46:55.666: E/AndroidRuntime(16107): at dalvik.system.NativeStart.main(Native Method)
08-11 18:46:55.666: E/AndroidRuntime(16107): Caused by: java.lang.NullPointerException
08-11 18:46:55.666: E/AndroidRuntime(16107): at com.prueba.bibliotecaappprueba.FileCache.<init>(FileCache.java:17)
08-11 18:46:55.666: E/AndroidRuntime(16107): at com.prueba.bibliotecaappprueba.ImageLoader.<init>(ImageLoader.java:33)
08-11 18:46:55.666: E/AndroidRuntime(16107): at com.prueba.bibliotecaappprueba.DetallesActivity.<init>(DetallesActivity.java:50)
08-11 18:46:55.666: E/AndroidRuntime(16107): at java.lang.Class.newInstanceImpl(Native Method)
08-11 18:46:55.666: E/AndroidRuntime(16107): at java.lang.Class.newInstance(Class.java:1319)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
08-11 18:46:55.666: E/AndroidRuntime(16107): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1964)
08-11 18:46:55.666: E/AndroidRuntime(16107): ... 11 more
08-11 18:47:02.604: D/dalvikvm(16143): GC_FOR_ALLOC freed 28K, 2% free 12847K/13027K, paused 16ms
我不知道为什么它在 Ginberbread 中有效，但在 ICS 中无效，请帮助我！谢谢。
我一直在寻求其他答案的帮助，但对我没有帮助：/谢谢！
编辑
这是活动代码正在崩溃。
public class DetallesActivity extends Activity {
//Variables
public static final String PREFS_NAME1 = "MyPrefsFile1";
public ImageLoader imageLoader;
{
imageLoader = new ImageLoader(null);
}
TextView txtNama;
TextView txtLinkImage;
TextView txtAlamat;
TextView txtTelepon;
TextView txtFax;
TextView txtEmail;
TextView txtWebsite;
String descarg;
String id_rs;
String nomb;
private ProgressDialog pDialog;
JSONParser jsonParser = new JSONParser();
private static final String url_detail_rs = "http://lectodrid.p.ht/LibrosPHP/Libros/detalles.php";
public int i = 0;
private static final String TAG_SUCCESS = "success";
private static final String TAG_DAFTAR_RS = "daftar_rs";
private static final String TAG_ID_RS = "id_rs";
public static final String TAG_NOMBRE_RS = "nombre_rs";
public static final String TAG_LINK_IMAGE_RS = "link_image_rs";
public static final String TAG_AUTOR_RS = "autor_rs";
public static final String TAG_CATEG_RS = "categ_rs";
public static final String TAG_LINK_DESCARGA_RS = "link_descarga_rs";;
private static final String TAG_SIPNOSIS_RS = "sipnosis";
public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
private ProgressDialog mProgressDialog;
//Variables fin
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_detail_rs);
Intent i = getIntent();
id_rs = i.getStringExtra(TAG_ID_RS);
new GetDetailrs().execute();
SharedPreferences settings = getSharedPreferences(PREFS_NAME1, 0);
boolean dialogShown = settings.getBoolean("dialogShown", false);
if (!dialogShown) {
// AlertDialog code here
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("El Botón de Descarga se encuentra al final de la descripción" + "\n" +
"- Haz Scroll hasta llegar al final."+ "\n" +
"- Pulsa el botón 'Descargar' y espera unos segundos." + "\n" +
"Podrás disfrutar de tu Libro descargado desde tu Lector de preferencia!. ")
.setTitle("Atencion!")
.setCancelable(false)
.setNeutralButton("Aceptar",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
((TextView)alert.findViewById(android.R.id.message)).setMovementMethod(LinkMovementMethod.getInstance());
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("dialogShown", true);
editor.commit();
}
}
//Termina Bundle
private void startDownload() {
String url = descarg;
new DownloadFileAsync().execute(url);
}
//Termina inicio de descarga
//Termina el inicio de descarga
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DIALOG_DOWNLOAD_PROGRESS:
mProgressDialog = new ProgressDialog(this);
mProgressDialog.setMessage("Descargando Libro..");
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
mProgressDialog.setCancelable(false);
mProgressDialog.show();
return mProgressDialog;
default:
return null;
}
}
//Termina el DIalog descargando...
class DownloadFileAsync extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
showDialog(DIALOG_DOWNLOAD_PROGRESS);
}
//termina einicio dialgo
@Override
protected String doInBackground(String... aurl) {
int count;
try {
URL url = new URL(aurl[0]);
HttpURLConnection c = (HttpURLConnection) url.openConnection();
c.setRequestMethod("GET");
c.setDoOutput(true);
c.connect();
int lenghtOfFile = c.getContentLength();
Log.d("ANDRO_ASYNC", "Lenght of file: " + lenghtOfFile);
InputStream input = new BufferedInputStream(url.openStream());
OutputStream output = new FileOutputStream("/sdcard/Mi Biblioteca/"+nomb+ ".epub");
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
publishProgress(""+(int)((total*100)/lenghtOfFile));
output.write(data, 0, count);
}
output.flush();
output.close();
input.close();
} catch (Exception e) {}
return null;
}
//Termina almacenamiento
protected void onProgressUpdate(String... progress) {
Log.d("ANDRO_ASYNC",progress[0]);
mProgressDialog.setProgress(Integer.parseInt(progress[0]));
}
//Progreso llega a 0
@Override
protected void onPostExecute(String unused) {
dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
Intent intent1 = getIntent();
finish();
startActivity(intent1);
}
//Progreso se cierra
}
class GetDetailrs extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(DetallesActivity.this);
pDialog.setMessage("Cargando esperar ... !");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
protected String doInBackground(String... params) {
Conexion();
if (i == 0) {
runOnUiThread(new Runnable() {
public void run() {
int success;
try {
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("id_rs",
id_rs));
JSONObject json = jsonParser.makeHttpRequest(
url_detail_rs, "GET", params);
Log.d("rs Detail", json.toString());
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
JSONArray productObj = json
.getJSONArray(TAG_DAFTAR_RS);
JSONObject daftar_rs = productObj.getJSONObject(0);
txtNama = (TextView) findViewById(R.id.nama_rs);
txtLinkImage = (TextView) findViewById(R.id.link_image_rs);
txtAlamat = (TextView) findViewById(R.id.alamat_rs);
txtTelepon = (TextView) findViewById(R.id.telepon_rs);
txtFax = (TextView) findViewById(R.id.fax_rs);
txtEmail = (TextView) findViewById(R.id.email_rs);
ImageView thumb_image = (ImageView) findViewById(R.id.list_image);
txtNama.setText(daftar_rs.getString(TAG_NOMBRE_RS));
txtLinkImage.setText(daftar_rs
.getString(TAG_LINK_IMAGE_RS));
txtAlamat.setText(daftar_rs
.getString(TAG_AUTOR_RS));
txtTelepon.setText(daftar_rs
.getString(TAG_CATEG_RS));
txtFax.setText(daftar_rs.getString(TAG_SIPNOSIS_RS));
txtEmail
.setText(daftar_rs.getString(TAG_LINK_DESCARGA_RS));
descarg = new String(daftar_rs.getString(TAG_LINK_DESCARGA_RS));
nomb = new String(daftar_rs.getString(TAG_NOMBRE_RS));
imageLoader.DisplayImage(daftar_rs
.getString(TAG_LINK_IMAGE_RS),
thumb_image);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
}
else{ finish();
}
return null;
}
protected void onPostExecute(String file_url) {
pDialog.dismiss();
//comiena prueba
File extStore = Environment.getExternalStorageDirectory();
File myFile = new File(extStore.getAbsolutePath() + "/Mi Biblioteca/"+nomb+".epub");
if(myFile.exists()){
Button leer = (Button) findViewById(R.id.Btnleer);
leer.setVisibility(View.VISIBLE);
Button dscr = (Button) findViewById(R.id.BtnDesc);
dscr.setVisibility(View.INVISIBLE);
}else{
Button leer = (Button) findViewById(R.id.Btnleer);
leer.setVisibility(View.INVISIBLE);
Button dscr = (Button) findViewById(R.id.BtnDesc);
dscr.setVisibility(View.VISIBLE);
}
//Termina el If e inicia descarga
Button dscr = (Button) findViewById(R.id.BtnDesc);
dscr.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
startDownload();}
});
//inicia abrir archivo
Button leer = (Button) findViewById(R.id.Btnleer);
leer.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v2) {
// TODO Auto-generated method stub
File file = new File("/sdcard/Mi Biblioteca/"+nomb+".epub");
Intent intentreadf = new Intent(Intent.ACTION_VIEW);
intentreadf.setDataAndType(Uri.fromFile(file),"application/epub+zip");
intentreadf.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
try {
startActivity(intentreadf);
}
catch (ActivityNotFoundException e) {
AlertDialog.Builder builder = new AlertDialog.Builder(DetallesActivity.this);
builder.setMessage("No hay instalada Aplicacion Para leer Epubs" +
"Desea descargar una sugerída por Droidteca?")
.setTitle("Advertencia")
.setCancelable(false)
.setNegativeButton("Cancelar",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
})
.setPositiveButton("Descargar",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
try {
startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=com.zoreader")));
} catch (android.content.ActivityNotFoundException anfe) {
startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("http://play.google.com/store/apps/details?id=com.zoreader")));
}
// metodo que se debe implementar
}
});
AlertDialog alert = builder.create();
alert.show();
}
}
});
//finaliza abrir archivo
}
}
private void Conexion() {
// TODO Auto-generated method stub
try {
if (InetAddress.getByName("www.google.com").isReachable(3000))
{ Intent nohay= new Intent(DetallesActivity.this, noActivity.class);
onStop();
i = 1;
startActivity(nohay);
}
else{}
} catch (UnknownHostException e) {
Intent nohay= new Intent(DetallesActivity.this, noActivity.class);
onStop();
i = 1;
startActivity(nohay);
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
Intent nohay= new Intent(DetallesActivity.this, noActivity.class);
onStop();
i = 1;
startActivity(nohay);
// TODO Auto-generated catch block
e.printStackTrace();
}}
}
但为什么它在 Ginberbread 中有效？但不在 ICS 中？