Develop Reference

Switching between activities without losing custom data

Currently using an Intent with startActivity() to switch between 2 activities which share an abstract superclass. However, whenever startActivity() is called the custom object inherited from the abstract superclass gets reset. Is there anyway to maintain this object between startActivity() calls? Serializing the object with OnSavedInstanceState does not work because this object contains a LinkedList.

Every time a class is created regardless if it extends a superclass (in this case an Activity), the superclass is recreated. You would extend the Activity to share common methods/functions and imports....
You want to stay away from Serializable, so you want your object class to implement Parcelable:
public class CustomObject implements Parcelable {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(this.name);
}
public CustomObject() {
}
protected CustomObject(Parcel in) {
this.name = in.readString();
}
public static final Parcelable.Creator<CustomObject> CREATOR = new Parcelable.Creator<CustomObject>() {
#Override
public CustomObject createFromParcel(Parcel source) {
return new CustomObject(source);
}
#Override
public CustomObject[] newArray(int size) {
return new CustomObject[size];
}
};
}
In the first activity you want to pass the List to the second Activity using an Intent:
public class StartActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
findViewById(R.id.btn1).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(StartActivity.this, ReceiveDataActivity.class);
i.putParcelableArrayListExtra("KEY", getCustomObjectList());
startActivity(i);
}
});
}
private ArrayList<CustomObject> getCustomObjectList() {
ArrayList<CustomObject> itemList = new ArrayList<>();
for (int i = 0; i < 5; i++) {
CustomObject customObject = new CustomObject();
customObject.setName("Name " + i);
itemList.add(customObject);
}
return itemList;
}
}
Then to get the list you would use getIntent():
public class ReceiveDataActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_receive_data);
List<CustomObject> itemList = getIntent().getParcelableArrayListExtra("KEY");
Toast.makeText(this, "List size = " + itemList.size(), Toast.LENGTH_SHORT).show();
}
}

Android:Parcel: unable to marshal value

I am getting below error while passing custom Arraylist in intent.
Parcel: unable to marshal value com.kahoindia.dev.models.KaHOStudentModel#62bceea
This is how am passing
KaHOSelectedObj selObject = new KaHOSelectedObj(); /*Parcelable */
selObject.setmIntent(mContext);
selObject.setSelectedStudents(mSelectedStudents);
Intent intent = new Intent(mContext, KaHOMyInputsActivity.class);
Bundle bundle = new Bundle();
bundle.putParcelable("SelectedStudents", selObject);
intent.putExtras(bundle);
startActivity(intent);
I am using Parcelable, but am getting unable to marshall.. run time error in the calling function at line start activity. Please help how to proceed with!
public class KaHOSelectedObj implements Parcelable
{
private Context mIntent;
private ArrayList<KaHOStudentModel> mSelectedStudentObj;
public Context getmIntent() {
return mIntent;
}
public void setmIntent(Context mIntent) {
this.mIntent = mIntent;
}
public ArrayList<KaHOStudentModel> getSelectedStudents() {
return mSelectedStudentObj;
}
public void setSelectedStudents(ArrayList<KaHOStudentModel> mObjects) {
this.mSelectedStudentObj = mObjects;
}
public static final Parcelable.Creator<KaHOSelectedObj> CREATOR = new Creator<KaHOSelectedObj>() {
#Override
public KaHOSelectedObj createFromParcel(Parcel source) {
KaHOSelectedObj selObj = new KaHOSelectedObj();
selObj.mSelectedStudentObj = source.readArrayList(null);
return selObj;
}
#Override
public KaHOSelectedObj[] newArray(int size) {
return new KaHOSelectedObj[size];
}
};
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeList(mSelectedStudentObj);
}
}

How to pass a two diamentional array from one activity to another activity?

I have a problem with passing my 2D string array from one activity to another activity
I tried some codes...but they show some errors
My string array is:
String[][] commuterDetails=new String[2][5];
commuterDetails=
{
{ "a", "b","c", "d","e" },
{"f", "g","h", "i","j" }
};
And I tried some codes
In first Activity
Intent summaryIntent = new Intent(this, Second.class);
Bundle b=new Bundle();
b.putSerializable("Array", commuterDetails);
summaryIntent.putExtras(b);
startActivity(summaryIntent);
In second activity
Bundle b = getIntent().getExtras();
String[][] list_array = (String[][])b.getSerializable("Array");
But it showing error
Caused by: java.lang.ClassCastException: [Ljava.lang.Object;
I am new in android, please help me

You may define a custom class which implements Parcelable and contains logic to read and write 2-dimensional-array from/to Parcel. Afterwards, put that parcelable object inside Bundle for transportation.
UPDATE
public class MyParcelable implements Parcelable{
public String[][] strings;
public String[][] getStrings() {
return strings;
}
public void setStrings(String[][] strings) {
this.strings = strings;
}
public MyParcelable() {
strings = new String[1][1];
}
public MyParcelable(Parcel in) {
strings = (String[][]) in.readSerializable();
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeSerializable(strings);
}
public static final Parcelable.Creator<MyParcelable> CREATOR = new Parcelable.Creator<MyParcelable>() {
#Override
public MyParcelable createFromParcel(Parcel in) {
return new MyParcelable(in);
}
#Override
public MyParcelable[] newArray(int size) {
return new MyParcelable[size];
}
};
}

make your commuterDetails static and access in other activity like this
FirstActivity.commuterDetails[][]

Android: passing object between activities and make it parcelable

New to Android programming. Having trouble to pass the object between activities and make it parcelable. Could somebody tell me what the problem could be? I want to know whether the logic is sound.
public class MainActivity extends Activity {
private Bundle MyActivityParams;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = new Intent(this, MyActivity.class);
MyActivityParams = fillInData(MyActivityParams);
intent.putExtras(MyActivityParams);
startActivity(intent, savedInstanceState);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
private Bundle fillInData(Bundle bundle){
bundle.putFloat("com.company.MyActivity.FL", 12);
bundle.putFloat("com.company.MyActivity.VH", 100);
bundle.putFloat("com.company.MyActivity.const", 1);
return bundle;
}
}
public class DisplayActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
displayData();
}
private void displayData(){
//ActivityData is from MyActivity
ActivityData data = new ActivityData(getIntent().getExtras());
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_display, menu);
return true;
}
}
public class MyActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
displayParams();
}
private void displayParams(){
ActivityData dataBundle = new ActivityData((getIntent()).getExtras());
transfer(dataBundle);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_algorithm, menu);
return true;
}
public void transfer(ActivityData incomingdata){
startActivity(incomingdata.getIntent());
}
protected static class ActivityData{
private Bundle data;
private TextView text;
private Intent intent;
public ActivityData(Bundle bundle){
/*data = bundle;
intent = new Intent(null, DisplayActivity.class);
text = new TextView(null);*/
}
public void display(String key){
this.text.setText(data.getString(key));
//not allowed: startActivity(intent);
//not allowed either: setContentView(text);
}
public Intent getIntent() {
return intent;
}
public void setIntent(Intent intent) {
this.intent = intent;
}
public TextView getText() {
return text;
}
public void setText(TextView text) {
this.text = text;
}
public Bundle getData() {
return data;
}
public void setData(Bundle data) {
this.data = data;
}
}
}

Let's have a Person class
public class Person {
private String name;
private String email;
private int age;
public Person(int age, String name, String email) {
this.age = age;
this.name = name;
this.email = email;
}
}
A parcelable one would look like this
public class ParcelablePerson implements Parcelable {
private final Person person;
private ParcelablePerson(Parcel parcel) {
this.person = new Person(parcel.readInt(), parcel.readString(), parcel.readString());
}
public ParcelablePerson(Person person) {
this.person = person;
}
public Person getPerson() {
return person;
}
#Override
public int describeContents() {
return 0;
}
// This is the method where you disassembly your object to pieces
#Override
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeInt(person.getAge());
parcel.writeString(person.getName());
parcel.writeString(person.getEmail());
}
public static final Creator<ParcelablePerson> CREATOR = new Creator<ParcelablePerson>() {
// And here you create a new instance from a parcel using the first constructor
#Override
public ParcelablePerson createFromParcel(Parcel parcel) {
return new ParcelablePerson(parcel);
}
#Override
public ParcelablePerson[] newArray(int size) {
return new ParcelablePerson[size];
}
};
}
The crucial thing in the process is to have the same order of the variables in private ParcelablePerson(Parcel parcel) constructor and public void writeToParcel(Parcel parcel, int flags) method... You can see it on the age property which is an int.

try this one.
ParcelTest.java
import java.util.HashMap;
import android.os.Parcel;
import android.os.Parcelable;
public class ParcelTest implements Parcelable {
private HashMap map;
public ParcelTest() {
map = new HashMap();
}
public ParcelTest(Parcel in) {
map = new HashMap();
readFromParcel(in);
}
public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
public ParcelTest createFromParcel(Parcel in) {
return new ParcelTest(in);
}
public ParcelTest[] newArray(int size) {
return new ParcelTest[size];
}
};
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(map.size());
for (String s: map.keySet()) {
dest.writeString(s);
dest.writeString(map.get(s));
}
}
public void readFromParcel(Parcel in) {
int count = in.readInt();
for (int i = 0; i < count; i++) {
map.put(in.readString(), in.readString());
}
}
public String get(String key) {
return map.get(key);
}
public void put(String key, String value) {
map.put(key, value);
}
}
ExampleSupplierActivity.java
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class ExampleSupplierActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ParcelTest p = new ParcelTest();
p.put("green", "go");
p.put("yellow", "wait");
p.put("red", "stop");
Bundle b = new Bundle();
b.putParcelable("com.example.trafficlight", p);
Intent i = new Intent(this, ExampleConsumerActivity.class);
i.putExtras(b);
startActivity(i);
}
}
ExampleConsumerActivity.java
import android.app.Activity;
import android.os.Bundle;
public class ExampleConsumerActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle b = getIntent().getExtras();
ParcelTest p = b.getParcelable("com.example.trafficlight");
String red = p.get("red");
// ...
}
}

try this out this code work for me. but i have implement serializable rather than parcelable.
Try to implement parcelable rather than serializable . and try it if its work. i havnt tried this but implementing parcelable.
To pass and object to another activity:
in activity A
make sure the class implements the serializable interface
create a new intent
create a new bundle
use the putSerializeable method to add the object to the bundle with a key
put the bundle in the intent by using the putExtras method
start the activity using the startActivity method
Specifically,
Intent intent = new Intent(ShoulderExerciseScreen.this, ExercisesScreen.class);
Bundle bundle = new Bundle();
bundle.putSerializable("exercise", new Exercise("BenchPress));
intent.putExtras(bundle);
startActivity(intent);
in activity B
declare and object of the type you want passed
use the getIntent method to get the intent
use the getSerializeableExtra to get the the value using the key
cast the returned value from getSerializeableExtra and the desired type
Specifically,
Exercise ex = (Exercise)getIntent().getSerializableExtra("exercise");
if(ex != null)
{
//do something
}

Parcelable data returning null

I have the following three classes.
Cricketers
public class Cricketers implements Parcelable {
private String name;
private String address;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
#Override
public int describeContents() {
return 0;
}
public Cricketers() {
}
#Override
public void writeToParcel(Parcel dest, int flag) {
dest.writeString(name);
dest.writeString(address);
dest.writeInt(age);
}
public Cricketers(Parcel in) {
this.name = in.readString();
this.address = in.readString();
this.age = in.readInt();
}
#SuppressWarnings("unchecked")
public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
public Cricketers createFromParcel(Parcel in) {
return new Cricketers(in);
}
public Cricketers[] newArray(int size) {
return new Cricketers[size];
}
};
}
Activity1
public class Activity1 extends Activity {
private ArrayList<Cricketers> cricketers;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
cricketers = new ArrayList<Cricketers>();
Cricketers object = new Cricketers();
object.setName("Sachin");
object.setAddress("Mumbai");
object.setAge(37);
cricketers.add(object);
Cricketers object1 = new Cricketers();
object1.setName("Sourav");
object1.setAddress("Kolkata");
object1.setAge(38);
cricketers.add(object1);
Cricketers object2 = new Cricketers();
object2.setName("Dravid");
object2.setAddress("Bengaluru");
object2.setAge(38);
cricketers.add(object2);
Intent intent = new Intent(this, Activity2.class);
intent.putExtra("cricketers", cricketers);
startActivity(intent);
cricketers = null;
}
Activity2
public class Activity2 extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Intent intent = getIntent();
Bundle bundle = intent.getExtras();
Cricketers cricketers = bundle.getParcelable("cricketers");
}
}
I am retrieving the data on Activity2 , but its returning cricketers = null .
Within the Activity1 class , the data "cricketers" is being properly added to the Intent.
Kindly provide your inputs.
Thanks in advance.

I have solved the issue ....
Changes need to done to the Activity2 class
public class Activity2 extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
ArrayList<Cricketers> data = new ArrayList<Cricketers>();
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Intent intent = getIntent();
Bundle bundle = intent.getExtras();
data = bundle.getParcelableArrayList("cricketers");
for (int count = 0; count < data.size(); count++) {
Cricketers cric = (Cricketers) data.get(count);
String name = cric.getName();
String address = cric.getAddress();
int age = cric.getAge();
}
}
}

I found some problem with AIDL cache ... if you change all your code abour the parcelable, or simple you refactor the name of the class. if you reinstall the app, or clear the app cache, the AIDL is still working and searching fot that refactored class.
I fix this task rebooting the device. It a crap to change code in the parcelable class but not see it works when reinstall the app, you MUST to reboot the device... or thats whar I do.
Thanks for the example dude ;) the activit2 was a bless!!