i am trying to record and reab back my list into file. It's working great until I restart my application. I am working with simulator (I don't have a real phone under Android)
Here is my function to record my class into a file :
public boolean writeRecordsToFile(String path, DummyContent object){
FileOutputStream fos;
ObjectOutputStream oos = null;
try {
fos = fileContext.openFileOutput(path, Context.MODE_PRIVATE);
oos = new ObjectOutputStream(fos);
oos.writeObject(object);
oos.close();
Log.d("fileManager", "Records write successfully");
return true;
} catch (Exception e) {
Log.e("fileManager", "Cant save records : " + e.getMessage());
return false;
}
finally {
if (oos != null)
try {
oos.close();
} catch (Exception e) {
Log.e("fileManager", "Error while closing stream "+e.getMessage());
}
}
}
Here is my reading Function :
public boolean readRecordsFromFile(String path){
FileInputStream fin;
ObjectInputStream ois=null;
try {
fin = fileContext.openFileInput(path);
ois = new ObjectInputStream(fin);
DummyContent records = (DummyContent) ois.readObject();
records.addItem("test", "test", "test");
ois.close();
Log.d("fileManager", "Records read successfully :\n" + records.toString());
Log.d("fileManager", "nbArticle found : " + String.valueOf(records.ITEMS.size()));
Log.d("fileManager", "article 0 title :\n" + records.ITEMS.get(0).content);
Log.d("fileManager", "article 10 title :\n" + records.ITEMS.get(10).content);
return true;
} catch (Exception e) {
Log.e("fileManager", "Cant read saved records : "+e.getMessage());
return false;
}
finally {
if (ois != null)
try {
ois.close();
} catch (Exception e) {
Log.e("fileManager", "Error in closing stream while reading records : "+e.getMessage());
}
}
}
and here is my class :
public class DummyContent implements Serializable {
/**
* An array of sample (dummy) items.
*/
public static List<DummyItem> ITEMS = new ArrayList<DummyItem>();
/**
* A map of sample (dummy) items, by ID.
*/
public static Map<String, DummyItem> ITEM_MAP = new HashMap<String, DummyItem>();
public void addItem(String first, String second, String third) {
DummyItem dummyItem = new DummyItem(first, second, third, android.R.drawable.ic_input_add);
ITEMS.add(dummyItem);
ITEM_MAP.put(dummyItem.id, dummyItem);
}
public void deleteAll() {
ITEMS = new ArrayList<DummyItem>();
ITEM_MAP = new HashMap<String, DummyItem>();
}
public void changeURL(Long index, String newURL) {
ITEMS.get(index.intValue()).url = newURL;
}
public void changeContent(Long index, String newContent) {
ITEMS.get(index.intValue()).contenu = newContent;
}
/**
* A dummy item representing a piece of content.
*/
public static class DummyItem {
public final String id;
public final String content;
public final String details;
public final int imageResource;
public String url;
public String contenu;
public DummyItem(String id, String content, String details, int imageResource) {
this.id = id;
this.content = content;
this.details = details;
this.imageResource = imageResource;
this.url = "";
this.contenu = "";
}
#Override
public String toString() {
return content;
}
}
}
Finally I read my file at the onCreate of my MainActivity (first activity at the lunching app) :
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
fileManager = new FileManager(this.getApplicationContext());
Log.d("Main", String.valueOf(fileManager.fileExist("Article.art")));
fileManager.readRecordsFromFile("Article.art"); /* Bug here : size of my array is empty but file's size is the same */
}
Here is my console return :
D/fileManager: size = 102
D/fileManager: Records read successfully :
D/fileManager: nbArticle found : 1 (because i add an item at the read
function) E/fileManager: Cant read saved records : Index: 10, Size: 1
I know it is working because when I write and read directly after the writting, I got all my items and I can read several times and I still got all items (this bug semms to be only present when I restart my application)
Maybe can I got help ?
Thanks !
The reason is very easy: You have declared some field as static, which are not covered by standard serialization: So, the contents of these fields were never written nor read from the file. That's why they "dissapeared" after a JVM restart.
Any field you want to be serialized/deserialized, you must declare it as instance member (not static).
See documentation on Serializable.
Related
I have a custom ListView that uses an object class for its data. The users can add new items to the listview, the arraylist is then saved in SharedPreferences. However, I also want to save each individual item so that I can use it in another Expandable ListView, how could I create a file for each individual item the user creates, or perhaps there is a better why to do it? Thanks in advance. Here is the object class:
public class Item implements Serializable{
String homework, date, classes;
public Item(String homework, String date, String classes){
this.homework = homework;
this.date = date;
this.classes = classes;
}
public String getHomework(){
return homework;
}
public String getDate(){
return date;
}
public String getClasses(){
return classes;
}
}
Why not use a database?There is a bit of setting up, but after the initial set up writing/reading data is very easy.
https://developer.android.com/training/basics/data-storage/databases.html
An example of serialize-deserialize class
public final class Serialize
{
private static final String className = Serialize.class.getName();
public static void save(Object saveThis, String serializeFileName, Context context)
{
FileOutputStream fos = null;
ObjectOutputStream oos = null;
try
{
if(saveThis != null)
{
fos = context.openFileOutput(serializeFileName, Context.MODE_PRIVATE);
oos = new ObjectOutputStream(fos);
oos.writeObject(saveThis);
}
}
catch(Throwable t)
{
//log it
}
finally
{
if(oos != null)
{
try{oos.close();}catch(Throwable t){}
}
if(fos != null)
{
try{fos.close();}catch(Throwable t){}
}
}
}
public static Object read(String serializeFileName, Context context)
{
FileInputStream fis = null;
ObjectInputStream ois = null;
Object readThis = null;
try
{
File file = context.getFileStreamPath(serializeFileName);
if(file != null && file.exists())
{
fis = context.openFileInput(serializeFileName);
ois = new ObjectInputStream(fis);
readThis = ois.readObject();
}
}
catch(Throwable t)
{
//log it
}
finally
{
if(ois != null)
{
try{ois.close();}catch(Throwable t){}
}
if(fis != null)
{
try{fis.close();}catch(Throwable t){}
}
}
return readThis;
}
public static boolean delete(String serializeFileName, Context context)
{
boolean deleted = false;
try
{
File file = context.getFileStreamPath(serializeFileName);
if(file != null && (file.exists()))
{
deleted = file.delete();
}
}
catch(Throwable t)
{
//log it
}
return deleted;
}
public static boolean exist(String serializeFileName, Context context)
{
boolean exist = false;
try
{
File file = context.getFileStreamPath(serializeFileName);
if(file != null && (file.exists()))
{
exist = true;
}
}
catch(Throwable t)
{
//log it
}
return exist;
}
}
Use the save method to save the serializable object in a file and the read method to read it.
Hi I'm trying to make a PACS server using Java. dcm4che appears to be quite popular. But I'm unable to find any good examples about it.
As a starting point I inspected dcmqrscp and it successfully stores a DICOM image. But I cannot manage to handle a C-MOVE call. Here's my CMove handler. It finds requested the DICOM file adds a URL and other stuff, it doesn't throw any exception yet client doesn't receive any files.
private final class CMoveSCPImpl extends BasicCMoveSCP {
private final String[] qrLevels;
private final QueryRetrieveLevel rootLevel;
public CMoveSCPImpl(String sopClass, String... qrLevels) {
super(sopClass);
this.qrLevels = qrLevels;
this.rootLevel = QueryRetrieveLevel.valueOf(qrLevels[0]);
}
#Override
protected RetrieveTask calculateMatches(Association as, PresentationContext pc, final Attributes rq, Attributes keys) throws DicomServiceException {
QueryRetrieveLevel level = QueryRetrieveLevel.valueOf(keys, qrLevels);
try {
level.validateRetrieveKeys(keys, rootLevel, relational(as, rq));
} catch (Exception e) {
e.printStackTrace();
}
String moveDest = rq.getString(Tag.MoveDestination);
final Connection remote = new Connection("reciverAE",as.getSocket().getInetAddress().getHostAddress(), 11113);
if (remote == null)
throw new DicomServiceException(Status.MoveDestinationUnknown, "Move Destination: " + moveDest + " unknown");
List<T> matches = DcmQRSCP.this.calculateMatches(keys);
if (matches.isEmpty())
return null;
AAssociateRQ aarq;
Association storeas = null;
try {
aarq = makeAAssociateRQ(as.getLocalAET(), moveDest, matches);
storeas = openStoreAssociation(as, remote, aarq);
} catch (Exception e) {
e.printStackTrace();
}
BasicRetrieveTask<T> retrieveTask = null;
retrieveTask = new BasicRetrieveTask<T>(Dimse.C_MOVE_RQ, as, pc, rq, matches, storeas, new BasicCStoreSCU<T>());
retrieveTask.setSendPendingRSPInterval(getSendPendingCMoveInterval());
return retrieveTask;
}
private Association openStoreAssociation(Association as, Connection remote, AAssociateRQ aarq)
throws DicomServiceException {
try {
return as.getApplicationEntity().connect(as.getConnection(),
remote, aarq);
} catch (Exception e) {
throw new DicomServiceException(
Status.UnableToPerformSubOperations, e);
}
}
private AAssociateRQ makeAAssociateRQ(String callingAET,
String calledAET, List<T> matches) {
AAssociateRQ aarq = new AAssociateRQ();
aarq.setCalledAET(calledAET);
aarq.setCallingAET(callingAET);
for (InstanceLocator match : matches) {
if (aarq.addPresentationContextFor(match.cuid, match.tsuid)) {
if (!UID.ExplicitVRLittleEndian.equals(match.tsuid))
aarq.addPresentationContextFor(match.cuid,
UID.ExplicitVRLittleEndian);
if (!UID.ImplicitVRLittleEndian.equals(match.tsuid))
aarq.addPresentationContextFor(match.cuid,
UID.ImplicitVRLittleEndian);
}
}
return aarq;
}
private boolean relational(Association as, Attributes rq) {
String cuid = rq.getString(Tag.AffectedSOPClassUID);
ExtendedNegotiation extNeg = as.getAAssociateAC().getExtNegotiationFor(cuid);
return QueryOption.toOptions(extNeg).contains(
QueryOption.RELATIONAL);
}
}
I added the code below to send a DICOM file as a response:
String cuid = rq.getString(Tag.AffectedSOPClassUID);
String iuid = rq.getString(Tag.AffectedSOPInstanceUID);
String tsuid = pc.getTransferSyntax();
try {
DcmQRSCP.this.as=as;
File f = new File("D:\\dcmqrscpTestDCMDir\\1.2.840.113619.2.30.1.1762295590.1623.978668949.886\\1.2.840.113619.2.30.1.1762295590.1623.978668949.887\\1.2.840.113619.2.30.1.1762295590.1623.978668949.888");
FileInputStream in = new FileInputStream(f);
InputStreamDataWriter data = new InputStreamDataWriter(in);
// !1! as.cmove(cuid,1,keys,tsuid,"STORESCU");
as.cstore(cuid,iuid,1,data,tsuid,rspHandlerFactory.createDimseRSPHandler(f));
} catch (Exception e) {
e.printStackTrace();
}
Throws this exception
org.dcm4che3.net.NoRoleSelectionException: No Role Selection for SOP Class 1.2.840.10008.5.1.4.1.2.2.2 - Study Root Query/Retrieve Information Model - MOVE as SCU negotiated
You should add a role to the application instance like:
applicationEntity.addTransferCapability(
new TransferCapability(null, "*", TransferCapability.Role.SCP, "*"));
I have a 'Person' class where i stored data like name, surname etc. I make 5 object type Person, add them to ArrayList, and save this ArrayList to file. Next i'm loading from this file ArrayList and i have 5 person. Problem is when i want save again for example 10 object Person. When i'm loading ArrayList from file i'm getting only 5 person from first writing. If i repeat this still i will have load data from first writing to this file. How i can fix this ?
public class Data {
static List<Person> persons = new ArrayList<Person>();
public static void main(String[] args) throws IOException {
Data.savePersons(5);
Data.loadPersons();
/** Clean 'persons' array for TEST of load data */
persons.removeAll(persons);
System.out.println("\n-----------\nNext Round\n-----------\n");
Data.savePersons(10);
Data.loadPersons();
}
/** Save a couple of Person Object to file C:/data.ser */
public static void savePersons(int noOfPersonToSave) throws IOException {
FileOutputStream fout = null;
ObjectOutputStream oos = null;
/** Make 5 'Person' object and add them to ArrayList 'persons' for example */
for (int i = 0; i < noOfPersonToSave; i++) {
Person personTest = new Person("name" + i, "surname" + i, "email" +i, "1234567890" +i);
persons.add(personTest);
}
try {
fout = new FileOutputStream("C:\\data.ser", true);
oos = new ObjectOutputStream(fout);
oos.writeObject(persons);
System.out.println("Saving '" + persons.size() + "' Object to Array");
System.out.println("persons.size() = " + persons.size());
System.out.println("savePersons() = OK");
} catch (Exception ex) {
System.out.println("Saving ERROR: " + ex.getMessage());
} finally {
if (oos != null) {
oos.close();
}
}
}
/** Load previously saved a couple of Person Object in file C:/data.ser */
public static void loadPersons() throws IOException {
FileInputStream fis = null;
ObjectInputStream ois = null;
try {
fis = new FileInputStream("C:\\data.ser");
ois = new ObjectInputStream(fis);
persons = (List<Person>) ois.readObject();
//persons.add(result);
System.out.println("-------------------------");
System.out.println("Loading '" + persons.size() + "' Object from Array");
System.out.println("persons.size() = " + persons.size());
System.out.println("loadPersons() = OK");
} catch (Exception e) {
System.out.println("-------------------------");
System.out.println("Loading ERROR: " + e.getMessage());
} finally {
if (ois != null) {
ois.close();
}
}
}}
class Person implements Serializable {
private static final long serialVersionUID = 1L;
private String name;
private String surname;
private String mail;
private String telephone;
public Person(String n, String s, String m, String t) {
name = n;
surname = s;
mail = m;
telephone = t;
}
public String getName() {
return name;
}
public String getSurname() {
return surname;
}
public String getMail() {
return mail;
}
public String getTelephone() {
return telephone;
}}
new FileOutputStream("C:\\data.ser", true)
You're passing true for the append parameter. So you're appending a list of 10 persons to the file, after the already existing list of 5 people. And since you only read one list, you read the first you wrote, which contains 5 persons.
Pass false instead of true.
so i can't figure out how to print an arraylist index (the first index so 0) to a text file. Basically, I have a Job class which stores 5 variables
public class Job {
public int teamNo;
public String regNo;
public String gridRef;
public String gridCopy;
public String toString() {
return "Job [teamNo=" + teamNo + ", regNo=" + regNo + ", gridRef="
+ gridRef + "";
}
and then I have an arraylist of type Job:
private static ArrayList<Job> teamNoOne = new ArrayList<Job>();
So the data all gets added fine, prints it out etc but I can't save it to a text file. this is my code, I just get the random hash code of it but I need it in human readable form.
try {
File file = new File("JOBS-DONE-LOG.txt");
FileOutputStream fs = new FileOutputStream(file);
ObjectOutputStream os = new ObjectOutputStream(fs);
System.out.println(teamNoOne.get(0));
os.writeObject(teamNoOne.get(0));
os.close();
} catch (IOException e1) {
e1.printStackTrace();
}
Can't figure out how to do it.
writeObject serializes the object in your file, it doesn't write it in textual form (http://docs.oracle.com/javase/7/docs/api/java/io/ObjectOutputStream.html#writeObject(java.lang.Object))
You must do it in another way: for example, you can use the BufferedWriter class and the write method to write the output of your toString() method.
Here is a complete example:
import java.io.File;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.util.ArrayList;
public class Job {
public String regNo;
public String gridRef;
public String gridCopy;
public String toString() {
return "Job [teamNo=" + teamNo + ", regNo=" + regNo + ", gridRef="
+ gridRef + "";
}
public static void main(String[] args) throws Exception {
ArrayList<Job> teamNoOne = new ArrayList<Job>();
// fill your array
Job job = new Job();
job.regNo = "123";
// continue to fill the jobs...
teamNoOne.add(job);
BufferedWriter writer = new BufferedWriter(new FileWriter("JOBS-DONE-LOG.txt"));
System.out.println(teamNoOne.get(0));
writer.write(teamNoOne.get(0).toString());
os.close();
}
}
Since you are trying to save an arraylist of type Job, it has to be serialized (Refer this).
public class Job implements java.io.Serializable
{
public int teamNo=0;
public String regNo="default";
public String gridRef="default";
public String gridCopy="default";
public String toString() {
return "Job [teamNo=" + teamNo + ", regNo=" + regNo + ", gridRef="
+ gridRef + "";
}
}
For Saving the file
try
{
FileOutputStream fileOut = new FileOutputStream(path);
ObjectOutputStream out = new ObjectOutputStream(fileOut);
out.writeObject(teamNoOne);
out.close();
fileOut.close();
}
catch(IOException i)
{
i.printStackTrace();
}
Thus you can load the arraylist back like
Object o = null;
try
{
FileInputStream fileIn = new FileInputStream(path);
ObjectInputStream in = new ObjectInputStream(fileIn);
o = in.readObject();
in.close();
fileIn.close();
}
catch(IOException i)
{
i.printStackTrace();
}
catch(ClassNotFoundException c)
{
c.printStackTrace();
}
Arraylist<Job> loaded_Job = (ArrayList<Job>) o;
Then print the arraylist
for(int i = 0; i < loaded_Job.size(); i++) {
loaded_Job.get(i).toString();
}
This happens because you didn't parameterize your ArrayList. Use generics when declaring your list:
ArrayList<Job> teamNoOne = new ArrayList<Job>();
Because now, though you have overriden your toString() method, teamNoOne.get(0) uses an Object's toString().
Is there any module in Java equivalent to python's shelve module? I need this to achieve dictionary like taxonomic data access. Dictionary-like taxonomic data access is a powerful way to save Python objects in a persistently easy access database format. I need something for the same purpose but in Java.
I also needed this, so I wrote one. A bit late, but maybe it'll help.
It doesn't implement the close() method, but just use sync() since it only hold the file open when actually writing it.
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.HashMap;
public class Shelf extends HashMap<String, Object> {
private static final long serialVersionUID = 7127639025670585367L;
private final File file;
public static Shelf open(File file) {
Shelf shelf = null;
try {
if (file.exists()) {
final FileInputStream fis = new FileInputStream(file);
ObjectInputStream ois = new ObjectInputStream(fis);
shelf = (Shelf) ois.readObject();
ois.close();
fis.close();
} else {
shelf = new Shelf(file);
shelf.sync();
}
} catch (Exception e) {
// TODO: handle errors
}
return shelf;
}
// Shelf objects can only be created or opened by the Shelf.open method
private Shelf(File file) {
this.file = file;
sync();
}
public void sync() {
try {
final FileOutputStream fos = new FileOutputStream(file);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(this);
oos.close();
fos.close();
} catch (Exception e) {
// TODO: handle errors
}
}
// Simple Test Case
public static void main(String[] args) {
Shelf shelf = Shelf.open(new File("test.obj"));
if (shelf.containsKey("test")) {
System.out.println(shelf.get("test"));
} else {
System.out.println("Creating test string. Run the program again.");
shelf.put("test", "Hello Shelf!");
shelf.sync();
}
}
}
You could use a serialisation library like Jackson which serialises POJOs to JSON.
An example from the tutorial:
Jackson's org.codehaus.jackson.map.ObjectMapper "just works" for
mapping JSON data into plain old Java objects ("POJOs"). For example,
given JSON data
{
"name" : { "first" : "Joe", "last" : "Sixpack" },
"gender" : "MALE",
"verified" : false,
"userImage" : "Rm9vYmFyIQ=="
}
It takes two lines of Java to turn it into a User instance:
ObjectMapper mapper = new ObjectMapper(); // can reuse, share globally
User user = mapper.readValue(new File("user.json"), User.class);
Where the User class looks something like this (from an entry on Tatu's blog):
public class User {
public enum Gender { MALE, FEMALE };
public static class Name {
private String _first, _last;
public String getFirst() { return _first; }
public String getLast() { return _last; }
public void setFirst(String s) { _first = s; }
public void setLast(String s) { _last = s; }
}
private Gender _gender;
private Name _name;
private boolean _isVerified;
private byte[] _userImage;
public Name getName() { return _name; }
public boolean isVerified() { return _isVerified; }
public Gender getGender() { return _gender; }
public byte[] getUserImage() { return _userImage; }
public void setName(Name n) { _name = n; }
public void setVerified(boolean b) { _isVerified = b; }
public void setGender(Gender g) { _gender = g; }
public void setUserImage(byte[] b) { _userImage = b; }
}