How to read all objects from ObjectInputStream
I have a file with some info how can I read all info?
Name names;
try (FileInputStream fileInputStream = new FileInputStream(file)) {
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
names = (Name) objectInputStream.readObject();
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
java file
edited Nov 25 '18 at 12:02
JSmith
1,49311226
asked Nov 25 '18 at 11:51
OppoOppo
85
add a comment |
I have a file with some info how can I read all info?
Name names;
try (FileInputStream fileInputStream = new FileInputStream(file)) {
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
names = (Name) objectInputStream.readObject();
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
java file
edited Nov 25 '18 at 12:02
JSmith
1,49311226
asked Nov 25 '18 at 11:51
OppoOppo
85
please check this link to know how to ask a question.
– JSmith
Nov 25 '18 at 12:01
If you are referring to serialization, I believe one stream can be one object. It can be a composite of multiple object (e.g. ArrayList), but a single object nevertheless.
– Sid
Nov 25 '18 at 12:04
I tried add objects into HashSet but had an exception java.io.StreamCorruptedException: invalid type code: AC. I input name using scanner and than I need to check if name already exist.
– Oppo
Nov 25 '18 at 12:09
add a comment |
I have a file with some info how can I read all info?
Name names;
try (FileInputStream fileInputStream = new FileInputStream(file)) {
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
names = (Name) objectInputStream.readObject();
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
java file
edited Nov 25 '18 at 12:02
JSmith
1,49311226
asked Nov 25 '18 at 11:51
OppoOppo
85
I have a file with some info how can I read all info?
Name names;
try (FileInputStream fileInputStream = new FileInputStream(file)) {
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
names = (Name) objectInputStream.readObject();
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
java file
java file
edited Nov 25 '18 at 12:02
JSmith
1,49311226
asked Nov 25 '18 at 11:51
OppoOppo
85
edited Nov 25 '18 at 12:02
JSmith
1,49311226
asked Nov 25 '18 at 11:51
OppoOppo
85
edited Nov 25 '18 at 12:02
JSmith
1,49311226
edited Nov 25 '18 at 12:02
JSmith
1,49311226
edited Nov 25 '18 at 12:02
JSmith
1,49311226
1,49311226
asked Nov 25 '18 at 11:51
OppoOppo
85
asked Nov 25 '18 at 11:51
OppoOppo
85
asked Nov 25 '18 at 11:51
OppoOppo
85
85
please check this link to know how to ask a question.
– JSmith
Nov 25 '18 at 12:01
If you are referring to serialization, I believe one stream can be one object. It can be a composite of multiple object (e.g. ArrayList), but a single object nevertheless.
– Sid
Nov 25 '18 at 12:04
I tried add objects into HashSet but had an exception java.io.StreamCorruptedException: invalid type code: AC. I input name using scanner and than I need to check if name already exist.
– Oppo
Nov 25 '18 at 12:09
add a comment |
please check this link to know how to ask a question.
– JSmith
Nov 25 '18 at 12:01
If you are referring to serialization, I believe one stream can be one object. It can be a composite of multiple object (e.g. ArrayList), but a single object nevertheless.
– Sid
Nov 25 '18 at 12:04
I tried add objects into HashSet but had an exception java.io.StreamCorruptedException: invalid type code: AC. I input name using scanner and than I need to check if name already exist.
– Oppo
Nov 25 '18 at 12:09
please check this link to know how to ask a question.
– JSmith
Nov 25 '18 at 12:01
please check this link to know how to ask a question.
– JSmith
Nov 25 '18 at 12:01
If you are referring to serialization, I believe one stream can be one object. It can be a composite of multiple object (e.g. ArrayList), but a single object nevertheless.
– Sid
Nov 25 '18 at 12:04
If you are referring to serialization, I believe one stream can be one object. It can be a composite of multiple object (e.g. ArrayList), but a single object nevertheless.
– Sid
Nov 25 '18 at 12:04
I tried add objects into HashSet but had an exception java.io.StreamCorruptedException: invalid type code: AC. I input name using scanner and than I need to check if name already exist.
– Oppo
Nov 25 '18 at 12:09
I tried add objects into HashSet but had an exception java.io.StreamCorruptedException: invalid type code: AC. I input name using scanner and than I need to check if name already exist.
– Oppo
Nov 25 '18 at 12:09
add a comment |
1 Answer
1
active
oldest
votes
You have several solution, all depending on the input:
You can iterate until the stream is fully consumed: I think that is the worse solution out of those I provide you. It is worse because you are checking if EOF was reached, whilst you should know when you're done (eg: your file format is wrong).
Set<Name> result = new HashSet<>();
try {
for (;;) {
result.add((Name)objectInputStream.readObject());
}
} catch (EOFException e) {
// End of stream
}
return result;
When producing the input, serialize a collection and invoke
readObject()on it.Serializationshould be able to read the collection, as long as each object implementsSerializable.
static void write(Path path, Set<Name> names) throws IOException {
try (OutputStream os = Files.newOutputStream(path);
ObjectOutputStream oos = new ObjectOutputStream(os)) {
oos.writeObject(names);
}
}
static Set<Name> read(Path path) throws IOException {
try (InputStream is = Files.newInputStream(path);
ObjectInputStream ois = new ObjectInputStream(is)) {
// WARN Files.newInputStream is not buffered; ObjectInputStream might
// be buffered (I don't remember).
return (Set<Name>) ois.readObject();
}
}
When producing the input, you can add a
intindicating the number of object to read, and iterate over it: this is useful in case where you don't really care of the collection (HashSet). The resulting file will be smaller (because you won't have theHashSetmetadata).
int result = objectInputStream.readInt();
Name names = new Name[result]; // do some check on result!
for (int i = 0; i < result; ++i) {
names[i] = (Name) objectInputStream.readObject();
}
Also, Set are good, but since they remove duplicate using hashCode()/equals() you may get less object if your definition of equals/hashCode changed after the fact (example: your Name was case sensitive and now it is not, eg: new Name("AA").equals(new Name("aa"))).
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
I tried your code and I got an java.io.EOFException
– Oppo
Nov 25 '18 at 12:21
That's good, this means that you reached the end of the file, there are no more object to read. Handle this exception properly, like printing a message saying "All the objects read" or something...
– Themelis
Nov 25 '18 at 12:22
And instead of array I can use HashSet? and print it to console?
– Oppo
Nov 25 '18 at 12:28
I fixed my example. Beside, converting an array to a collection should not be a problem if you are tackling serialization.
– NoDataFound
Nov 25 '18 at 18:34
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You have several solution, all depending on the input:
You can iterate until the stream is fully consumed: I think that is the worse solution out of those I provide you. It is worse because you are checking if EOF was reached, whilst you should know when you're done (eg: your file format is wrong).
Set<Name> result = new HashSet<>();
try {
for (;;) {
result.add((Name)objectInputStream.readObject());
}
} catch (EOFException e) {
// End of stream
}
return result;
When producing the input, serialize a collection and invoke
readObject()on it.Serializationshould be able to read the collection, as long as each object implementsSerializable.
static void write(Path path, Set<Name> names) throws IOException {
try (OutputStream os = Files.newOutputStream(path);
ObjectOutputStream oos = new ObjectOutputStream(os)) {
oos.writeObject(names);
}
}
static Set<Name> read(Path path) throws IOException {
try (InputStream is = Files.newInputStream(path);
ObjectInputStream ois = new ObjectInputStream(is)) {
// WARN Files.newInputStream is not buffered; ObjectInputStream might
// be buffered (I don't remember).
return (Set<Name>) ois.readObject();
}
}
When producing the input, you can add a
intindicating the number of object to read, and iterate over it: this is useful in case where you don't really care of the collection (HashSet). The resulting file will be smaller (because you won't have theHashSetmetadata).
int result = objectInputStream.readInt();
Name names = new Name[result]; // do some check on result!
for (int i = 0; i < result; ++i) {
names[i] = (Name) objectInputStream.readObject();
}
Also, Set are good, but since they remove duplicate using hashCode()/equals() you may get less object if your definition of equals/hashCode changed after the fact (example: your Name was case sensitive and now it is not, eg: new Name("AA").equals(new Name("aa"))).
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
I tried your code and I got an java.io.EOFException
– Oppo
Nov 25 '18 at 12:21
That's good, this means that you reached the end of the file, there are no more object to read. Handle this exception properly, like printing a message saying "All the objects read" or something...
– Themelis
Nov 25 '18 at 12:22
And instead of array I can use HashSet? and print it to console?
– Oppo
Nov 25 '18 at 12:28
I fixed my example. Beside, converting an array to a collection should not be a problem if you are tackling serialization.
– NoDataFound
Nov 25 '18 at 18:34
add a comment |
You have several solution, all depending on the input:
You can iterate until the stream is fully consumed: I think that is the worse solution out of those I provide you. It is worse because you are checking if EOF was reached, whilst you should know when you're done (eg: your file format is wrong).
Set<Name> result = new HashSet<>();
try {
for (;;) {
result.add((Name)objectInputStream.readObject());
}
} catch (EOFException e) {
// End of stream
}
return result;
When producing the input, serialize a collection and invoke
readObject()on it.Serializationshould be able to read the collection, as long as each object implementsSerializable.
static void write(Path path, Set<Name> names) throws IOException {
try (OutputStream os = Files.newOutputStream(path);
ObjectOutputStream oos = new ObjectOutputStream(os)) {
oos.writeObject(names);
}
}
static Set<Name> read(Path path) throws IOException {
try (InputStream is = Files.newInputStream(path);
ObjectInputStream ois = new ObjectInputStream(is)) {
// WARN Files.newInputStream is not buffered; ObjectInputStream might
// be buffered (I don't remember).
return (Set<Name>) ois.readObject();
}
}
When producing the input, you can add a
intindicating the number of object to read, and iterate over it: this is useful in case where you don't really care of the collection (HashSet). The resulting file will be smaller (because you won't have theHashSetmetadata).
int result = objectInputStream.readInt();
Name names = new Name[result]; // do some check on result!
for (int i = 0; i < result; ++i) {
names[i] = (Name) objectInputStream.readObject();
}
Also, Set are good, but since they remove duplicate using hashCode()/equals() you may get less object if your definition of equals/hashCode changed after the fact (example: your Name was case sensitive and now it is not, eg: new Name("AA").equals(new Name("aa"))).
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
I tried your code and I got an java.io.EOFException
– Oppo
Nov 25 '18 at 12:21
That's good, this means that you reached the end of the file, there are no more object to read. Handle this exception properly, like printing a message saying "All the objects read" or something...
– Themelis
Nov 25 '18 at 12:22
And instead of array I can use HashSet? and print it to console?
– Oppo
Nov 25 '18 at 12:28
I fixed my example. Beside, converting an array to a collection should not be a problem if you are tackling serialization.
– NoDataFound
Nov 25 '18 at 18:34
add a comment |
You have several solution, all depending on the input:
You can iterate until the stream is fully consumed: I think that is the worse solution out of those I provide you. It is worse because you are checking if EOF was reached, whilst you should know when you're done (eg: your file format is wrong).
Set<Name> result = new HashSet<>();
try {
for (;;) {
result.add((Name)objectInputStream.readObject());
}
} catch (EOFException e) {
// End of stream
}
return result;
When producing the input, serialize a collection and invoke
readObject()on it.Serializationshould be able to read the collection, as long as each object implementsSerializable.
static void write(Path path, Set<Name> names) throws IOException {
try (OutputStream os = Files.newOutputStream(path);
ObjectOutputStream oos = new ObjectOutputStream(os)) {
oos.writeObject(names);
}
}
static Set<Name> read(Path path) throws IOException {
try (InputStream is = Files.newInputStream(path);
ObjectInputStream ois = new ObjectInputStream(is)) {
// WARN Files.newInputStream is not buffered; ObjectInputStream might
// be buffered (I don't remember).
return (Set<Name>) ois.readObject();
}
}
When producing the input, you can add a
intindicating the number of object to read, and iterate over it: this is useful in case where you don't really care of the collection (HashSet). The resulting file will be smaller (because you won't have theHashSetmetadata).
int result = objectInputStream.readInt();
Name names = new Name[result]; // do some check on result!
for (int i = 0; i < result; ++i) {
names[i] = (Name) objectInputStream.readObject();
}
Also, Set are good, but since they remove duplicate using hashCode()/equals() you may get less object if your definition of equals/hashCode changed after the fact (example: your Name was case sensitive and now it is not, eg: new Name("AA").equals(new Name("aa"))).
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
You have several solution, all depending on the input:
You can iterate until the stream is fully consumed: I think that is the worse solution out of those I provide you. It is worse because you are checking if EOF was reached, whilst you should know when you're done (eg: your file format is wrong).
Set<Name> result = new HashSet<>();
try {
for (;;) {
result.add((Name)objectInputStream.readObject());
}
} catch (EOFException e) {
// End of stream
}
return result;
When producing the input, serialize a collection and invoke
readObject()on it.Serializationshould be able to read the collection, as long as each object implementsSerializable.
static void write(Path path, Set<Name> names) throws IOException {
try (OutputStream os = Files.newOutputStream(path);
ObjectOutputStream oos = new ObjectOutputStream(os)) {
oos.writeObject(names);
}
}
static Set<Name> read(Path path) throws IOException {
try (InputStream is = Files.newInputStream(path);
ObjectInputStream ois = new ObjectInputStream(is)) {
// WARN Files.newInputStream is not buffered; ObjectInputStream might
// be buffered (I don't remember).
return (Set<Name>) ois.readObject();
}
}
When producing the input, you can add a
intindicating the number of object to read, and iterate over it: this is useful in case where you don't really care of the collection (HashSet). The resulting file will be smaller (because you won't have theHashSetmetadata).
int result = objectInputStream.readInt();
Name names = new Name[result]; // do some check on result!
for (int i = 0; i < result; ++i) {
names[i] = (Name) objectInputStream.readObject();
}
Also, Set are good, but since they remove duplicate using hashCode()/equals() you may get less object if your definition of equals/hashCode changed after the fact (example: your Name was case sensitive and now it is not, eg: new Name("AA").equals(new Name("aa"))).
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
edited Nov 25 '18 at 22:06
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
answered Nov 25 '18 at 12:13
NoDataFoundNoDataFound
5,8211841
5,8211841
I tried your code and I got an java.io.EOFException
– Oppo
Nov 25 '18 at 12:21
That's good, this means that you reached the end of the file, there are no more object to read. Handle this exception properly, like printing a message saying "All the objects read" or something...
– Themelis
Nov 25 '18 at 12:22
And instead of array I can use HashSet? and print it to console?
– Oppo
Nov 25 '18 at 12:28
I fixed my example. Beside, converting an array to a collection should not be a problem if you are tackling serialization.
– NoDataFound
Nov 25 '18 at 18:34
add a comment |
I tried your code and I got an java.io.EOFException
– Oppo
Nov 25 '18 at 12:21
That's good, this means that you reached the end of the file, there are no more object to read. Handle this exception properly, like printing a message saying "All the objects read" or something...
– Themelis
Nov 25 '18 at 12:22
And instead of array I can use HashSet? and print it to console?
– Oppo
Nov 25 '18 at 12:28
I fixed my example. Beside, converting an array to a collection should not be a problem if you are tackling serialization.
– NoDataFound
Nov 25 '18 at 18:34
I tried your code and I got an java.io.EOFException
– Oppo
Nov 25 '18 at 12:21
I tried your code and I got an java.io.EOFException
– Oppo
Nov 25 '18 at 12:21
That's good, this means that you reached the end of the file, there are no more object to read. Handle this exception properly, like printing a message saying "All the objects read" or something...
– Themelis
Nov 25 '18 at 12:22
That's good, this means that you reached the end of the file, there are no more object to read. Handle this exception properly, like printing a message saying "All the objects read" or something...
– Themelis
Nov 25 '18 at 12:22
And instead of array I can use HashSet? and print it to console?
– Oppo
Nov 25 '18 at 12:28
And instead of array I can use HashSet? and print it to console?
– Oppo
Nov 25 '18 at 12:28
I fixed my example. Beside, converting an array to a collection should not be a problem if you are tackling serialization.
– NoDataFound
Nov 25 '18 at 18:34
I fixed my example. Beside, converting an array to a collection should not be a problem if you are tackling serialization.
– NoDataFound
Nov 25 '18 at 18:34
add a comment |
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please check this link to know how to ask a question.
– JSmith
Nov 25 '18 at 12:01
If you are referring to serialization, I believe one stream can be one object. It can be a composite of multiple object (e.g. ArrayList), but a single object nevertheless.
– Sid
Nov 25 '18 at 12:04
I tried add objects into HashSet but had an exception java.io.StreamCorruptedException: invalid type code: AC. I input name using scanner and than I need to check if name already exist.
– Oppo
Nov 25 '18 at 12:09