I want to convert this generic class to a parcelable object, but I don't have very clear the concepts of the issue.
Class:
public class Type<T> implements Parcelable {
// T stands for "Type"
private T t;
public void set(T t) { this.t = t; }
public T get() { return t; }
}
This is what I've tried,. but I know that this is not correct, or maybe this is not complete.
public class Type<T> implements Parcelable {
// T stands for "Type"
private T t;
protected Type(Parcel in) {
}
public void set(T t) { this.t = t; }
public T get() { return t; }
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
}
public static final Creator< Type > CREATOR = new Creator< Type >() {
#Override
public Type createFromParcel(Parcel in) {
return new Type(in);
}
#Override
public Type[] newArray(int size) {
return new Type[size];
}
};
}
This is similar approach as vikas kumar but guarantte that you can pass only Parcelable as T parameter so you avoid exception.
public class Type<T extends Parcelable> implements Parcelable {
private T t;
protected Type(Parcel in) {
t = (T) in.readValue(t.getClass().getClassLoader());
}
public static final Creator<Type> CREATOR = new Creator<Type>() {
#Override
public Type createFromParcel(Parcel in) {
return new Type(in);
}
#Override
public Type[] newArray(int size) {
return new Type[size];
}
};
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeValue(t);
}
}
Your generic data type may cause runtime error
so make sure you implements Parcelable and also the class you are passing should implement Parcelable otherwise it will cause runtime error.
public class Type<T extends Parcelable> implements Parcelable {
// T stands for "Type"
private T t;
public void set(T t) { this.t = t; }
public T get() { return t; }
protected Type(Parcel in) {
final String className = in.readString();
try {
t = in.readParcelable(Class.forName(className).getClassLoader());
} catch (ClassNotFoundException e) {
Log.e("readParcelable", className, e);
}
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeValue(t);
}
#SuppressWarnings("unused")
public static final Parcelable.Creator<Type> CREATOR = new Parcelable.Creator<Type>() {
#Override
public Type createFromParcel(Parcel in) {
return new Type(in);
}
#Override
public Type[] newArray(int size) {
return new Type[size];
}
};
}
Related
I'm trying to pass an ArrayList of unknown class type that extend an abstract class, to another activity using Parcelable. Since its not possible to use Parcelable.CREATOR on the abstract class, there is an error when I try to create the ArrayList: in.readTypedList(AbstractChannel.CREATOR), see below:
public class TvNetwork implements Parcelable {
public String name;
public ArrayList<? extends AbstractChannel> mChannels;
public TvNetwork(String name, ArrayList<? extends AbstractChannel> channels) {
this.name = name;
this.mChannels = channels;
}
protected TvNetwork(Parcel in) {
name = in.readString();
mChannels = in.readTypedList(AbstractChannel.CREATOR); // here is the error
}
public static final Creator<TvNetwork> CREATOR = new Creator<TvNetwork>() {
#Override
public TvNetwork createFromParcel(Parcel in) {
return new TvNetwork(in);
}
#Override
public TvNetwork[] newArray(int size) {
return new TvNetwork[size];
}
};
public ArrayList<? extends AbstractChannel> getChannels() {
return mChannels;
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(name);
dest.writeTypedList(mChannels);
}
}
Writing seems to work but not reading. This obviously does not work either, but explains a bit more what I want to do:
in.readTypedList(mChannels, <? extends AbstractChannel>.class.getClassLoader());
Any ideas?
I have coded a class like this.but when i'm using this there is runtime error is occured in this overided method
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeValue(synclistener);
}
Myclass
public class SyncListenEntity implements Parcelable {
private LocationServiceProvider.LocationSyncNotifier synclistener;
public LocationServiceProvider.LocationSyncNotifier getSynclistener() {
return synclistener;
}
public void setSynclistener(LocationServiceProvider.LocationSyncNotifier synclistener) {
this.synclistener = synclistener;
}
public SyncListenEntity() {
}
protected SyncListenEntity(Parcel in) {
synclistener = (LocationServiceProvider.LocationSyncNotifier) in.readValue(LocationServiceProvider.LocationSyncNotifier.class.getClassLoader());
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeValue(synclistener);
}
public static final Parcelable.Creator<SyncListenEntity> CREATOR = new Parcelable.Creator<SyncListenEntity>() {
#Override
public SyncListenEntity createFromParcel(Parcel in) {
return new SyncListenEntity(in);
}
#Override
public SyncListenEntity[] newArray(int size) {
return new SyncListenEntity[size];
}
};
}
LocationNotifier
public interface LocationNotifier {
void onNewLocationArrived(Location loaction, String privider);
}
Exception:
java.lang.RuntimeException: Parcel: unable to marshal value
Caused by: java.lang.RuntimeException: Parcel: unable to marshal value
com.library.gps.SyncListenEntity.writeToParcel(SyncListenEntity.java)
android.app.ActivityManagerProxy.getIntentSender(ActivityManagerNative.java:3835)
com.library.gps.LocationServiceProvider.enableUserTrackingService(LocationServiceProvider.java:64)
com.ceylonlinux.multilac.activity.FrmHome.onCreate(FrmHome.java:365)
You are trying to use writeParcel() to write an object that does not conform to the requirements stated in the documentation. You can only write values into a Parcel of the types stated in the javadoc.
Below are my code snippet for using WritableComparator, but it does not work
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
public class MovieComparator extends WritableComparator{
public MovieComparator(){
super(Movie.class);
}
#Override
public int compare(WritableComparable o,WritableComparable o2){
System.out.println("in compare");
Movie m = (Movie)o;
Movie m2 = (Movie)o2;
System.out.println(m.compareTo(m2));
return m.movieId.compareTo(m2.movieId);
}
}
public class Movie implements WritableComparable {
Text movieId;
Text movieTitle;
public Movie(Text movieId, Text movieTitle) {
this.movieId = movieId;
this.movieTitle = movieTitle;
}
public Movie(){
}
public String getMovieId() {
return movieId.toString();
}
public void setMovieId(String movieId) {
this.movieId = new Text(movieId);
}
public String getMovieTitle() {
return movieTitle.toString();
}
public void setMovieTitle(String movieTitle) {
this.movieTitle = new Text(movieTitle);
}
#Override
public void readFields(DataInput in) throws IOException {
//movieId = in.read;
movieId.readFields(in);
movieTitle.readFields(in);
}
#Override
public void write(DataOutput out) throws IOException {
//out.writeUTF(movieId);
//out.writeUTF(movieTitle);
movieId.write(out);
movieTitle.write(out);
}
#Override
public int compareTo(Movie o) {
// System.out.println("in compareTo");
int res=movieTitle.compareTo(o.movieTitle);
return res;
}
#Override
public int hashCode(){
return movieId.hashCode();
}
#Override
public boolean equals(Object o){
Movie m=(Movie)o;
return movieId.equals(m.movieId);
}
#Override
public String toString(){
return movieTitle.toString();
}
}
In driver class I am setting the comparator by below line
job.setSortComparatorClass(MovieComparator.class);
Can any body tell me where I am wrong in this at it gives exception below
14/09/08 14:17:03 WARN mapred.LocalJobRunner: job_local_0001
java.io.IOException: Spill failed
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1029)
at org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:691)
at org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
at com.impetus.MovieMapper.map(MovieMapper.java:44)
at com.impetus.MovieMapper.map(MovieMapper.java:1)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:212)
I found the issue that Instead of using super(Movie.class), I will have to use super(Movie.class,true). As by sending true, WritableComparator will instantiate the object other wise it will pass null in compare method
I am working on an Android App, and I am trying to pass information using Parcelable. So here's what I've got.
import android.os.Parcel;
import android.os.Parcelable;
abstract class Role implements Parcelable {
private String name;
private String image;
public Role() {
}
public Role(Parcel read) {
name = read.readString();
image = read.readString();
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
public String toString() {
return this.name;
}
public static final Parcelable.Creator<Role> CREATOR =
new Parcelable.Creator<Role>() {
public Role createFromParcel(Parcel source) {
return new Role(source);
}
public Role[] newArray(int size) {
return new Role[size];
}
};
public int describeContents() {
// TODO Auto-generated method stub
return 0;
}
public void writeToParcel(Parcel dest, int flags) {
// TODO Auto-generated method stub
dest.writeString(name);
dest.writeString(image);
}
}
However, when I try to compile I get the Error (where I placed the comment)
Cannot instantiate the Type Role
Any thoughts on this?
Best regards
I have not used parcelable in abstract class myself, but it should be ok. You may want to check here or more generally here
I have a VERY similar class (two strings) but its a public static class.
I do new() on my string members in the constructor.
Yout class Role is defined as abstract, the abstract classes cannot be instantiated.
just define your class Role:
class Role implements Parcelable {
//...
}
As qjuanp mentioned, one cannot instantiate an abstract class (as per Java's and common OOP definition; you cannot instantiate something that is abstract, it has got to be more defined).
I'm sure you're trying to use some subclasses of Role (that's about the only way you can use both abstract and implement Parcelable here), consider using this approach:
public abstract class A implements Parcelable {
private int a;
protected A(int a) {
this.a = a;
}
public void writeToParcel(Parcel out, int flags) {
out.writeInt(a);
}
protected A(Parcel in) {
a = in.readInt();
}
}
public class B extends A {
private int b;
public B(int a, int b) {
super(a);
this.b = b;
}
public static final Parcelable.Creator<B> CREATOR = new Parcelable.Creator<B>() {
public B createFromParcel(Parcel in) {
return new B(in);
}
public B[] newArray(int size) {
return new B[size];
}
};
public int describeContents() {
return 0;
}
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
out.writeInt(b);
}
private B(Parcel in) {
super(in);
b = in.readInt();
}
}
I am trying to create a Parcelable class. The class extends TableRow:
import android.content.Context;
import android.os.Parcel;
import android.os.Parcelable;
import android.widget.TableRow;
public class AcmTableRow extends TableRow implements Parcelable{
private int index;
public boolean isSection;
private String volumeLink;
private String rowId;
private String cfr;
private static Context context;
public AcmTableRow(Context context) {
super(context);
}
public AcmTableRow(Context context, Parcel in) {
super(context);
AcmTableRow.context = context;
readFromParcel(in);
}
private void readFromParcel(Parcel in) {
//strValue = in.readString();
//intValue = in.readInt();
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
//dest.writeString(strValue);
//dest.writeInt(intValue);
}
public void setIndex(int index) {
this.index = index;
}
public int getIndex() {
return index;
}
public void setRowId(String rowId) {
this.rowId = rowId;
}
public String getRowId() {
return rowId;
}
public void setCfr(String cfr) {
this.cfr = cfr;
}
public String getCfr() {
return cfr;
}
public void setVolumeLink(String volumeLink) {
this.volumeLink = volumeLink;
}
public String getVolumeLink() {
return volumeLink;
}
public static final Parcelable.Creator<AcmTableRow> CREATOR = new Parcelable.Creator<AcmTableRow>() {
public AcmTableRow createFromParcel(Parcel in) {
return new AcmTableRow(context, in);
}
public AcmTableRow[] newArray(int size) {
return new AcmTableRow[size];
}
};
}
I am confused as what I need to put in:
readFromParcel(Parcel in)
And
writeToParcel(Parcel dest, int flags)
Any explanation or help is greatly appreciated.
Thank you
Phil
The writeToParcel method simply flattens the object into a parcel. You'll use this when you need to pass your object between activities. In your case, it should look like this:
public void writeToParcel (Parcel dest, int flags)
{
dest.writeInt(index);
dest.writeBoolean(isSection);
dest.writeString(volumeLink);
dest.writeString(rowId);
dest.writeString(cfr);
}
I've never had to use readFromParcel and I'm not sure you need to here either. Your object will be created from the Parcel when you call the appropriate method in your next activity.
Just a quick note, you probably don't want to pass the context in your parcelable class. I'm not even sure you can. You'll need to assign the context when you inflate the parcelable again later on.
This is a simple working Parcelable example:
public class ParcelableExample implements Parcelable {
private int intMember;
private String stringMember;
/*
* Getters and setters
* ....
*/
/*
* Constructors
* ....
*/
/*
* Custom parcelable implementation
*/
private ParcelableExample(Parcel in) {
// notice that we are reading in the same order as we have written
intMember = in.readInt();
stringMember = in.readString();
}
#Override
public int describeContents() {
return hashCode();
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(intMember);
dest.writeString(stringMember);
}
#SuppressWarnings("rawtypes")
public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
public ParcelableExample createFromParcel(Parcel in) {
return new ParcelableExample(in);
}
public ParcelableExample[] newArray(int size) {
return new ParcelableExample[size];
}
}