So I'm trying to pass an instance of a class I create by intent to a new activity.
public class Room implements Serializable{
/**
*
*/
private static final long serialVersionUID = 6857044522819206055L;
int roomID;
String roomName;
ArrayList<MarkerHolder> markerHolders = new ArrayList<MarkerHolder>();
public int getRoomID() {
return roomID;
}
public void setRoomID(int roomID) {
this.roomID = roomID;
}
public String getRoomName() {
return roomName;
}
public void setRoomName(String roomName) {
this.roomName = roomName;
}
public ArrayList<MarkerHolder> getMarkerHolders() {
return markerHolders;
}
public void setMarkerHolders(ArrayList<MarkerHolder> markerHolders) {
this.markerHolders = markerHolders;
}
}
public class MarkerHolder implements Serializable{
/**
*
*/
private static final long serialVersionUID = -7334724625702415322L;
String marker;
String markerTag;
public String getMarker() {
return marker;
}
public void setMarker(String marker) {
this.marker = marker;
}
public String getMarkerTag() {
return markerTag;
}
public void setMarkerTag(String markerTag) {
this.markerTag = markerTag;
}
}
And I try to pass that class by
Intent svc = new Intent(this, RoomUploader.class);
svc.putExtra("room", room);
try{
startService(svc);
}catch (Exception e){
e.printStackTrace();
}
and I keep getting a Not Serializable Exception which I can't figure out. Both classes implement serializable and have serial Ids. The member variables are just strings, ints, and an array of another class that is also serializable that contains only strings. As far as I know all these things should be serializable, what else could cause this error? Thanks in advance.
Are those classes inner classes of your activity or another class? If so, they have a reference to their outer class (which may or may not be serializable), and you can solve this by making those classes static.
Example:
public static class Room implements Serializable
{
//your implementation
}
public static class MarkerHolder implements Serializable
{
//your implementation
}
Try changing ArrayList to a native array of MarkerHolder:
MarkerHolder[] markerHolders;
Update: My bad. I've always used native array for serialization so not aware ArrayList is indeed serialzable.
Your code looks right. What was the exact error message printed in the logcat (i.e. which class threw the serialization exception)?
Another solution (more work) is to make your objects implement the Parcable interface.
Try to use getApplicationContext() or context instaed of this.
Related
currently I'm playing with GSON and got into some trouble that I couldn't solve on my own.
I've got these three classes:
One abstract class CustomEntity
public abstract class CustomEntity {
private View customView;
public CustomEntity() {}
public void setCustomView(View customView) {
this.customView = customView;
}
public View getCustomView() {
return customView;
}
}
Another class LastChange which extends from CustomEntity
public class LastChange extends CustomEntity {
public Config config;
public LastChange() {}
#Override
public String toString() {
return "LastChange:" + config.toString();
}
public Config getConfig() {
return config;
}
public void setConfig(Config config) {
this.config = config;
}
}
And a third class Config
public class Config extends CustomEntity {
public String config;
public String nav_items;
public Config() {}
#Override
public String toString() {
return "config data:" + config + ", " + nav_items;
}
public String getConfig() {
return config;
}
public void setConfig(String config) {
this.config = config;
}
public String getNav_items() {
return nav_items;
}
public void setNav_items(String nav_items) {
this.nav_items = nav_items;
}
}
In the MainActivity I've tried to deserialize the following JSON into a LastChange object with GSON.
String lastChangeJson = "{\"config\":{\"config\":\"2016-07-20 15:32:14\",\"nav_items\":\"2016-08-24 12:36:06\"},\"background_images\":{\"background_url_landscape\":\"2015-07-28 17:21:56\",\"background_url\":\"2015-07-28 17:21:56\",\"icon_for_accessory_view\":\"2015-07-28 17:21:56\",\"icon_for_route_view\":\"2015-07-28 17:21:56\",\"background_url_landscape_big\":\"2015-07-28 17:21:56\",\"background_url_big\":\"2015-07-28 17:21:56\"},\"nav_content\":[{\"last_change\":\"2016-06-29 11:06:16\",\"pageId\":\"10262\"},{\"last_change\":\"2016-08-24 12:36:06\",\"pageId\":\"10264\"},{\"last_change\":\"2016-08-09 16:13:03\",\"pageId\":\"10378\"},{\"last_change\":\"2016-08-09 16:13:03\",\"pageId\":\"10263\"},{\"last_change\":\"2016-07-20 15:32:14\",\"pageId\":\"10265\"}]}";
CustomEntity lastChangeEntity = gson.fromJson(lastChangeJson, LastChange.class);
The code above gives me the following exception:
java.lang.SecurityException: Can't make method constructor accessible
at java.lang.reflect.Constructor.setAccessible(Constructor.java:336)
at com.google.gson.internal.ConstructorConstructor.newDefaultConstructor(ConstructorConstructor.java:101)
at com.google.gson.internal.ConstructorConstructor.get(ConstructorConstructor.java:83)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:99)
at com.google.gson.Gson.getAdapter(Gson.java:423)...
But if I remove the attribute "customView" from the class CustomEntity and its getter and setter, the deserialization works fine.
Anybody got an idea on how I can tell GSON to ignore class attributes, if they don't appear in my json?
Thanks in advance.
When building new gson instance:
Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
Annotate every field you want to serialize with #Expose:
#Expose
public Config config;
Edit:
One small side note - try to avoid keeping references to views (or any Context-related objects) in your models. You may encounter memory leaks if you persist instances of this model in static way and it smells like mixing presentation and data layers, which is never good thing to do for code readability and maintainability.
I need to start an activity from 2 different screens that have two different models but, both models have some shared information which is the one that I need in the new activity. The problem is that I cannot make those models to extend from the same parent, as one of the models already extends one parent. I have thought about creating an interface that contains the shared methods but, if I do that, then how can I put that interface in the bundle required to start the next activity?
I add some simplified code in order to clarify my situation:
public class A extends Model implements CustomInterface {
String name;
String address;
public String getName(){
return name;
}
public String getAddress() {
return address;
}
}
public class B implements CustomInterface {
String name;
public String getName() {
return name;
}
}
public interface CustomInterface {
String getName();
}
My problem is that I need to start an activity with a bundle with the shared information between both models. So, I would like to put CustomInterface in a bundle. How could I do that?
Thanks in advance.
So, I would like to put CustomInterface in a bundle
you could let CustomInterface extend Parcelable. E.g.
public interface CustomInterface extends Parcelable {
String getName();
}
this way the classes implementing CustomInterface will have to implements the method defined in the Parcelable interface. If implemented correctly, you will be able to pass those objects around without problems
Create a singleton class, then you can share data without passing it:
public class MySingleton
{
private static MySingleton instance;
public String customVar;
public static MySingleton getInstance()
{
if (instance == null)
{
// Create the instance
instance = new MySingleton();
}
// Return the instance
return instance;
}
private MySingleton()
{
// Constructor hidden because this is a singleton
}
public void getSomeData()
{
return something;
}
public void getSomeOtherData()
{
return somethingelse;
}
}
Then in your classes:
public class A extends Model {
String name;
String address;
public String getName(){
return name;
}
public String getAddress() {
return address;
}
public String doSomethingWithSharedData(){
MySingleton model = MySingleton.getInstance();
String somedata = model.getSomeData();
}
}
public class B {
String name;
public String getName() {
return name;
}
public String doSomethingDifferentWithSharedData(){
MySingleton model = MySingleton.getInstance();
String somedata = model.getSomeOtherData();
}
}
I'm a new to android please help me with the following.
I'm having an integer value which stores the id of a checked radiobutton. I need to access this value throughout the various classes of my app for a validation purpose.
Please let me know how to declare and access this variable from all the classes.
Thank you.
U can use:
MainActivity.class
Public static int myId;
In other Activities.
int otherId=MainActivity.myId;
following singleton pattern is the only way to do this.in java/android if u create a instance for a class every time it create a new object.what you should do is
1.create a model class and make its as singleton
2.try to access the modelclass from every class
public class CommonModelClass
{
private static CommonModelClass singletonObject;
/** A private Constructor prevents any other class from instantiating. */
private CommonModelClass()
{
// Optional Code
}
public static synchronized CommonModelClass getSingletonObject()
{
if (singletonObject == null)
{
singletonObject = new CommonModelClass();
}
return singletonObject;
}
/**
* used to clear CommonModelClass(SingletonClass) Memory
*/
public void clear()
{
singletonObject = null;
}
public Object clone() throws CloneNotSupportedException
{
throw new CloneNotSupportedException();
}
//getters and setters starts from here.it is used to set and get a value
public String getcheckBox()
{
return checkBox;
}
public void setcheckBox(String checkBox)
{
this.checkBox = checkBox;
}
}
accessing the model class values from other class
commonModelClass = CommonModelClass.getSingletonObject();
commonModelClass.getcheckBox();
http://javapapers.com/design-patterns/singleton-pattern/
You can declare your integer variable as static and access in any class.Like this
class A{
static int a;
}
You can access in another class like this.
class B{
int b = A.a;
}
I am trying to pass my own custom object into a bundle:
Bundle b = new Bundle();
STMessage message = (STMessage)a.getAdapter().getItem(position);
b.putObject("message",message);
I get the error:
The method putObject(String, Object) is undefined for the type Bundle
One way is to have your custom object implement the Parcelable interface and use Bundle.putParcelable/Bundle.getParcelable
Model Class
package com.sam.bundleobjectpass;
import java.io.Serializable;
/**
* Created by Samir on 31.8.2016.
*/
public class Model implements Serializable {
private String name;
private String surName;
private int age;
public Model(String name, String surName, int age) {
this.name = name;
this.surName = surName;
this.age = age;
}
public String getName() {
return name;
}
public String getSurName() {
return surName;
}
public int getAge() {
return age;
}
}
MainActivity
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Model model = new Model("Sam", "Sami",32);
Intent i = new Intent(MainActivity.this, ReceiverActivity.class);
i.putExtra("Editing", model); // sending our object. In Kotlin is the same
startActivity(i);
}
}
ReceiverActivity
public class ReceiverActivity extends Activity {
TextView txt_name;
TextView txt_surname;
TextView txt_age;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
txt_name = (TextView)findViewById(R.id.txt_name);
txt_surname = (TextView)findViewById(R.id.txt_surname);
txt_age = (TextView)findViewById(R.id.txt_age);
// receiving our object
Model model = (Model) getIntent().getSerializableExtra("Editing");
txt_name.setText(model.getName());
txt_surname.setText(model.getSurName());
txt_age.setText(""+model.getAge());
}
}
// Kotlin
val model: ProgramModel? = intent.getSerializableExtra("Editing") as ProgramModel?
model?.let { // means if not null or empty
txt_act_daily_topic.text = it.title
}
Since using Parsable is designed for high performance IPC transport as mentioned in some of the comments, I tried using a different approach.
My approach uses GSON library by google.
Example
public class Person{
private String name;
private int age;
// Getter and Setters omitted
}
You can have a method in utility class that returns Gson instance, this is for the sake of clean code and organisation. I will use GsonBuilder incase someone what to register custom adapter.
public class Utils {
private static Gson gson;
public static Gson getGsonParser() {
if(null == gson) {
GsonBuilder builder = new GsonBuilder();
gson = builder.create();
}
return gson;
}
}
Moment of truth!
PUT
Bundle args = new Bundle();
String personJsonString = Utils.getGsonParser().toJson(person);
args.putString(PERSON_KEY, personJsonString);
GET
Bundle args = getArguments();
String personJsonString = args.getString(PERSON_KEY);
Person person= Utils.getGsonParser().fromJson(personJsonString, Person.class);
Currently I don't know the performance limitation of this approach. But it works just fine
Make your custom object Parcelable or Serializable then use putParcelable or putSerializable.
Depending on the complexity of your object one or other may be easier.
As Ryan stated. Also if you only want to pass one object on a soft kill consider using onRetainConfigurationInstance and getLastNonConfigurationInstance to pass the serializable object. The entire object tree must be serializable. If you are passing the object via an intent, consider refactoring the object code to a Parceable code later, once the architecture has stabilized. Finally, consider using the fully qualified name of the class when storing the object into the Bundle as in:
inPWState= (PasswordState) getIntent().getSerializableExtra("jalcomputing.confusetext.PasswordState");
Hope that helps.
JAL
It's work
if you make your object class as Serializable
class your_data_class implements Serializable
I am having a class EmployeeInfo as the following:
public class EmployeeInfo {
private int id; // Employee ID
private String name; // Employee Name
private int age;// Employee Age
public int getEmployeeID() {
return id;
}
public void setEmployeeID(int id) {
this.id = id;
}
public String getEmployeeName() {
return name;
}
public void setEmployeeName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age= age;
}
}
ArrayList<EmployeeInfo> employeeInfo object contains the emplyoyee info data for multiple employees.
I want to transfer the data( ArrayList employeeInfo ) from Activity1 to Activity2.
Is using Parcelable the only way to transfer the data from Activity1 to Activity2?
If not , what are the alternatives.
If yes ,kindly provide the prototype code of Parcelable along with the sample code on how to transfer the object data from Activity1 to Activity2.
Here is my implementation of Parceleble:
public class ProfileData implements Parcelable {
private int gender;
private String name;
private String birthDate;
public ProfileData(Parcel source) {
gender = source.readInt();
name = source.readString();
birthDate = source.readString();
}
public ProfileData(int dataGender, String dataName, String dataBDate) {
gender = dataGender;
name = dataName;
birthDate = dataBDate;
}
// Getters and Setters are here
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel out, int flags) {
out.writeInt(gender);
out.writeString(name);
out.writeString(birthDate);
}
public static final Parcelable.Creator<ProfileData> CREATOR
= new Parcelable.Creator<ProfileData>() {
public ProfileData createFromParcel(Parcel in) {
return new ProfileData(in);
}
public ProfileData[] newArray(int size) {
return new ProfileData[size];
}
};
}
and how I transfer data:
Intent parcelIntent = new Intent().setClass(ActivityA.this, ActivityB.class);
ProfileData data = new ProfileData(profile.gender, profile.getFullName(), profile.birthDate);
parcelIntent.putExtra("profile_details", data);
startActivity(parcelIntent);
and take data:
Bundle data = getIntent().getExtras();
ProfileData profile = data.getParcelable("profile_details");
You can simply let your EmployeeInfo class implement Serializable. Or you can send data like this
intent.putExtra("id", employInfo.getEmployeeID());
intent.putExtra("name", employInfo.getEmployeeName());
intent.putExtra("age", employInfo.getAge());
If you need to transfer a list of your custom classes, i'd use the first approach. So you would be able to put entire list as Serializable.
However they said that everyone should use Parcelable instead because it's "way faster". Tbh, I'd never used it, because it needs more effort and I doubt somebody can realize the difference in speed in a regular application w/o a load of data sending via intent
Good question. Looking at the docs and doing armchair coding:
It may be possible to pass an object between Activities by calling putExtras(Bundle) and myBundle.putSerializable. The object and the entire object tree would need to implement serializable.
JAL
EDIT: The answer is yes:
It is possible to pass an immutable object between Activities by calling putExtras(Bundle) and myBundle.putSerializable. The object and the entire object tree would need to implement serializable. This is a basic tenet of Object Oriented Programming, passing of stateful messages.
First we create the immutable object by declaring a new class:
package jalcomputing.confusetext;
import java.io.Serializable;
/*
* Immutable messaging object to pass state from Activity Main to Activity ManageKeys
* No error checking
*/
public final class MainManageKeysMessage implements Serializable {
private static final long serialVersionUID = 1L;
public final int lengthPassword;
public final long timeExpire;
public final boolean isValidKey;
public final int timeoutType;
public MainManageKeysMessage(int lengthPassword, long timeExpire, boolean isValidKey, int timeoutType){
this.lengthPassword= lengthPassword;
this.timeExpire= timeExpire;
this.isValidKey= isValidKey;
this.timeoutType= timeoutType;
}
}
Then we create an immutable stateful instance of the class, a message, in the parent activity, and send it in an intent as in:
private void LaunchManageKeys() {
Intent i= new Intent(this, ManageKeys.class); // no param constructor
// push data (4)
MainManageKeysMessage message= new MainManageKeysMessage(lengthPassword,timeExpire,isValidKey,timeoutType);
Bundle b= new Bundle();
b.putSerializable("jalcomputing.confusetext.MainManageKeysMessage", message);
i.putExtras(b);
startActivityForResult(i,REQUEST_MANAGE_KEYS); // used for callback
}
Finally, we retrieve the object in the child activity.
try {
inMessage= (MainManageKeysMessage) getIntent().getSerializableExtra("jalcomputing.confusetext.MainManageKeysMessage");
lengthPassword= inMessage.lengthPassword;
timeoutType= inMessage.timeoutType;
isValidKey= inMessage.isValidKey;
timeExpire= inMessage.timeExpire;
} catch(Exception e){
lengthPassword= -1;
timeoutType= TIMEOUT_NEVER;
isValidKey= true;
timeExpire= LONG_YEAR_MILLIS;
}
Well there is another way to transfer an object.We can use application to transfer object and this is way is far better way in my opinion.
First of all create your custom application in your main package.
public class TestApplication extends Application {
private Object transferObj;
#Override
public void onCreate() {
super.onCreate();
// ACRA.init(this);
}
public Object getTransferObj() {
return transferObj;
}
public void setTransferObj(Object transferObj) {
this.transferObj = transferObj;
}
}
Now use setTransfer and get transfer methods to move abjects from one activity to other like:
To Transfer:
((TestApplication) activity.getApplication()).setTransferObj(Yous object);
ToRecieve:
Object obj=((TestApplication) activity.getApplication()).getTransferObj();
NOTE
Always remember to make entry of this application in manifest application tag:
<application
android:name=".TestApplication">
</application>
You can convert your object to jsonstring using Gson or Jakson and pass using intent as string and read the json in another activity.