How to pass an object from one activity to another

Question

I am trying to work on sending an object of my customer class from one Activity and display it in another Activity.

The code for the customer class:

public class Customer {

    private String firstName, lastName, Address;
    int Age;

    public Customer(String fname, String lname, int age, String address) {

        firstName = fname;
        lastName = lname;
        Age = age;
        Address = address;
    }

    public String printValues() {

        String data = null;

        data = "First Name :" + firstName + " Last Name :" + lastName
        + " Age : " + Age + " Address : " + Address;

        return data;
    }
}

I want to send its object from one Activity to another and then display the data on the other Activity.

How can I achieve that?

Answer 1

You can try to use that class. The limitation is that it can't be used outside of one process.

One activity:

 final Object obj1 = new Object();
 final Intent in = new Intent();
 in.putExtra(EXTRA_TEST, new Sharable(obj1));

Other activity:

final Sharable s = in.getExtras().getParcelable(EXTRA_TEST);
final Object obj2 = s.obj();

public final class Sharable implements Parcelable {

    private Object mObject;

    public static final Parcelable.Creator < Sharable > CREATOR = new Parcelable.Creator < Sharable > () {
        public Sharable createFromParcel(Parcel in ) {
            return new Sharable( in );
        }


        @Override
        public Sharable[] newArray(int size) {
            return new Sharable[size];
        }
    };

    public Sharable(final Object obj) {
        mObject = obj;
    }

    public Sharable(Parcel in ) {
        readFromParcel( in );
    }

    Object obj() {
        return mObject;
    }


    @Override
    public int describeContents() {
        return 0;
    }


    @Override
    public void writeToParcel(final Parcel out, int flags) {
        final long val = SystemClock.elapsedRealtime();
        out.writeLong(val);
        put(val, mObject);
    }

    private void readFromParcel(final Parcel in ) {
        final long val = in .readLong();
        mObject = get(val);
    }

    /////

    private static final HashMap < Long, Object > sSharableMap = new HashMap < Long, Object > (3);

    synchronized private static void put(long key, final Object obj) {
        sSharableMap.put(key, obj);
    }

    synchronized private static Object get(long key) {
        return sSharableMap.remove(key);
    }
}

Answer 2

Create two methods in your custom Class like this

public class Qabir {

    private int age;
    private String name;

    Qabir(){
    }

    Qabir(int age,String name){
        this.age=age; this.name=name;
    }   

    // method for sending object
    public String toJSON(){
        return "{age:" + age + ",name:\"" +name +"\"}";
    }

    // method for get back original object
    public void initilizeWithJSONString(String jsonString){

        JSONObject json;        
        try {
            json =new JSONObject(jsonString );
            age=json.getInt("age");
            name=json.getString("name");
        } catch (JSONException e) {
            e.printStackTrace();
        } 
    }
}

Now in your sender Activity do like this

Qabir q= new Qabir(22,"KQ");    
Intent in=new Intent(this,SubActivity.class);
in.putExtra("obj", q.toJSON());
startActivity( in);

And in your receiver Activity

Qabir q =new Qabir();
q.initilizeWithJSONString(getIntent().getStringExtra("obj"));

Answer 3

There are a couple of ways by which you can access variables or objects in other classes or Activity.

A. Database

B. Shared preferences.

C. Object serialization.

D. A class which can hold common data can be named as Common Utilities. It depends on you.

E. Passing data through Intents and Parcelable Interface.

It depends upon your project needs.

A. Database

SQLite is an open source database which is embedded into Android. SQLite supports standard relational database features like SQL syntax, transactions and prepared statements.

Tutorials

B. Shared preferences

Suppose you want to store username. So there will now be two things, a key username, value value.

How to store

 // Create object of SharedPreferences.
 SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);

 //Now get Editor
 SharedPreferences.Editor editor = sharedPref.edit();

 //Put your value
 editor.putString("userName", "stackoverlow");

 //Commits your edits
 editor.commit();

Using putString(), putBoolean(), putInt(), putFloat(), and putLong() you can save your desired dtatype.

How to fetch

SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
String userName = sharedPref.getString("userName", "Not Available");

http://developer.android.com/reference/android/content/SharedPreferences.html

C. Object serialization

Object serlization is used if we want to save an object state to send it over a network or you can use it for your purpose also.

Use Java beans and store in it as one of his fields and use getters and setter for that.

JavaBeans are Java classes that have properties. Think of properties as private instance variables. Since they're private, the only way they can be accessed from outside of their class is through methods in the class. The methods that change a property's value are called setter methods, and the methods that retrieve a property's value are called getter methods.

public class VariableStorage implements Serializable  {

    private String inString;

    public String getInString() {
        return inString;
    }

    public void setInString(String inString) {
        this.inString = inString;
    }
}

Set the variable in your mail method by using

VariableStorage variableStorage = new VariableStorage();
variableStorage.setInString(inString);

Then use object serialzation to serialize this object and in your other class deserialize this object.

In serialization an object can be represented as a sequence of bytes that includes the object's data as well as information about the object's type and the types of data stored in the object.

After a serialized object has been written into a file, it can be read from the file and deserialized. That is, the type information and bytes that represent the object and its data can be used to recreate the object in memory.

If you want tutorial for this refer to:

• Serialization in Java (blog post)

• Get variable in other classes (Stack Overflow)

D. CommonUtilities

You can make a class by yourself which can contain common data which you frequently need in your project.

Sample

public class CommonUtilities {

    public static String className = "CommonUtilities";

}

E. Passing data through intents

Please refer the tutorial Android – Parcel data to pass between Activities using Parcelable classes for this option of passing data.

Answer 4

Implement your class with Serializable. Let's suppose that this is your entity class:

import java.io.Serializable;

@SuppressWarnings("serial") //With this annotation we are going to hide compiler warnings
public class Deneme implements Serializable {

    public Deneme(double id, String name) {
        this.id = id;
        this.name = name;
    }

    public double getId() {
        return id;
    }

    public void setId(double id) {
        this.id = id;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    private double id;
    private String name;
}

We are sending the object called dene from X activity to Y activity. Somewhere in X activity;

Deneme dene = new Deneme(4,"Mustafa");
Intent i = new Intent(this, Y.class);
i.putExtra("sampleObject", dene);
startActivity(i);

In Y activity we are getting the object.

Intent i = getIntent();
Deneme dene = (Deneme)i.getSerializableExtra("sampleObject");

That's it.

Answer 5

One option could be letting your custom class implement the Serializable interface and then you can pass object instances in the intent extra using the putExtra(Serializable..) variant of the Intent#putExtra() method.

Pseudocode:

//To pass:
intent.putExtra("MyClass", obj);

// To retrieve object in second Activity
getIntent().getSerializableExtra("MyClass");

Note: Make sure each nested class of your main custom class has implemented Serializable interface to avoid any serialization exceptions. For example:

class MainClass implements Serializable {

    public MainClass() {}

    public static class ChildClass implements Serializable {

        public ChildClass() {}
    }
}

Answer 6

I made a singleton helper class that holds temporary objects.

public class IntentHelper {

    private static IntentHelper _instance;
    private Hashtable<String, Object> _hash;

    private IntentHelper() {
        _hash = new Hashtable<String, Object>();
    }

    private static IntentHelper getInstance() {
        if(_instance==null) {
            _instance = new IntentHelper();
        }
        return _instance;
    }

    public static void addObjectForKey(Object object, String key) {
        getInstance()._hash.put(key, object);
    }

    public static Object getObjectForKey(String key) {
        IntentHelper helper = getInstance();
        Object data = helper._hash.get(key);
        helper._hash.remove(key);
        helper = null;
        return data;
    }
}

Instead of putting your objects within Intent, use IntentHelper:

IntentHelper.addObjectForKey(obj, "key");

Inside your new Activity, you can get the object:

Object obj = (Object) IntentHelper.getObjectForKey("key");

Bear in mind that once loaded, the object is removed to avoid unnecessary references.