java - putextra - parcelable

如何在Android上將對像從一項活動傳遞給另一項活動 (20)



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;



  1. I know that static is bad, but it seems that we're forced to use it here. The problem with parceables/seriazables is that the two activities have duplicate instances of the same object = waste of memory and CPU.

    public class IntentMailBox {
        static Queue<Object> content = new LinkedList<Object>();

Calling activity

Intent intent = new Intent(LevelsActivity.this, LevelActivity.class);

Called activity (note that onCreate() and onResume() may be called multiple times when the system destroys and recreates activities)

if (IntentMailBox.content.size()>0)
    level = (Level) IntentMailBox.content.poll();
    // Here you reload what you have saved in onPause()
  1. Another way is to declare a static field of the class that you want to pass in that very class. It will serve only for this purpose. Don't forget that it can be null in onCreate, because your app package has been unloaded from memory by system and reloaded later.

  2. Bearing in mind that you still need to handle activity lifecycle, you may want to write all the data straight to shared preferences, painful with complex data structures as it is.

我使用parcelable將數據從一個活動發送到另一個活動。 這是我的代碼在我的項目中正常工作。

public class Channel implements Serializable, Parcelable {

    /**  */
    private static final long serialVersionUID = 4861597073026532544L;

    private String cid;
    private String uniqueID;
    private String name;
    private String logo;
    private String thumb;

     * @return The cid
    public String getCid() {
        return cid;

     * @param cid
     *     The cid to set
    public void setCid(String cid) {
        this.cid = cid;

     * @return The uniqueID
    public String getUniqueID() {
        return uniqueID;

     * @param uniqueID
     *     The uniqueID to set
    public void setUniqueID(String uniqueID) {
        this.uniqueID = uniqueID;

     * @return The name
    public String getName() {
        return name;

     * @param name
     *            The name to set
    public void setName(String name) { = name;

     * @return the logo
    public String getLogo() {
        return logo;

     * @param logo
     *     The logo to set
    public void setLogo(String logo) {
        this.logo = logo;

     * @return the thumb
    public String getThumb() {
        return thumb;

     * @param thumb
     *     The thumb to set
    public void setThumb(String thumb) {
        this.thumb = thumb;

    public Channel(Parcel in) {

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

        public Channel[] newArray(int size) {

            return new Channel[size];

    public void readFromParcel(Parcel in) {
        String[] result = new String[5];

        this.cid = result[0];
        this.uniqueID = result[1]; = result[2];
        this.logo = result[3];
        this.thumb = result[4];

    public int describeContents() {
        return 0;

    public void writeToParcel(Parcel dest, int flags) {

        dest.writeStringArray(new String[] { this.cid, this.uniqueID,
      , this.logo, this.thumb});


Bundle bundle = new Bundle();
bundle.putParcelableArrayList("channel",(ArrayList<Channel>) channels);
Intent intent = new Intent(ActivityA.this,ActivityB.class);


Bundle getBundle = this.getIntent().getExtras();
List<Channel> channelsList = getBundle.getParcelableArrayList("channel");

Android Activity objects can be destroyed and reconstituted. So, you will need to use another approach to look them - or any object they create !!! - up. That is, you could pass as static class reference but then the object handle (Java calls these "references", as does SmallTalk; but they are not references in the sense of C or assembly) will be possibly invalid later because a "feature" of Android OE is any Activity can be annihilated and reconstituted later.

The original question asked "How to pass object from one activity to another in Android" and nobody has answered that. For sure, you can serialized (Serializable, Parcelable, to/from JSON) and pass a copy of the object's data and a new object having the same data could be created; but it will NOT have the same references/handles. Also, many others mentioned you can store the reference in a static store. And that will work unless Android decides to onDestroy your Activity.

So, to really solve the original question you would need a static lookup plus each object will update its reference when/if it is recreated. Eg each Android Activity would relist itself if its onCreate is called. You can also see how some people use the task list to search out an Activity by name. (system is temporarily destroying this instance of the activity to save space..getRunningTasks, the task list is effectively a specialized listing of the most recent object instance of each Activity).

For reference:

Stopped: "The activity is completely obscured by another activity (the activity is now in the "background"). A stopped activity is also still alive (the Activity object is retained in memory , it maintains all state and member information, but is not attached to the window manager). However, it is no longer visible to the user and it can be killed by the system when memory is needed elsewhere."

onDestroy "system is temporarily destroying this instance of the activity to save space."

So, the Message Bus is a workable solution. It basically "punts". Rather than try to have references to objects; then you re-architect your design to use MessagePassing instead of SequentialCode. Exponentially harder to debug; but it lets you ignore these sort of OperatingEnvironment understandings. Effectively, each object method access is inverted so the caller posts a Message and the object itself defines a handler for that message. Lots more code but can make it robust with the Android OE restrictions.

If all you want is the top Activity (typical thing in Android apps due to "Context" being needed everywhere), then you can just have each Activity lists itself as "top" in the static global space whenever its onResume is called. Then your AlertDialog or whatever which needs a context can just grab it from there. Also, its a bit yucky to use a global but can simplifying passing a Context up and down everywhere and, for sure, when you use a MessageBus then IT IS global anyways.

Create two methods in your custom Class like this

public class Qabir {

    private int age;
    private String name;


    Qabir(int age,String 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 );
        } catch (JSONException e) {

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();

Hello all I see a lot of good options but I was wondering why Binding hasn't been used?

Passing a reference to an object just seems more efficient to me than serializing and desterilizing objects, but I have not done a deep dive to see if that is what is going on behind the scenes.

Creating a Binder is simple enough...

public class MyBinder extends Binder {

    private Object myObject;

    public MyBinder(Object object) {
        myObject = object;

    public Object getObject() {
        return myObject;


And creating the parcelable to use it isn't that bad ether.

public class MyParcelable implements Parcelable {

    private Object myObject;

    public MyParcelable() {

    public MyParcelable(Parcel parcel) {
        myObject = ((MyBinder)parcel.readStrongBinder()).getObject();

    public void setObject(Object object) {
        myObject = object;

    public Object getObject() {
        return myObject;

    public void writeToParcel(Parcel parcel, int flags) {
        parcel.writeStrongBinder(new MyBinder(myObject));

    public int describeContents() {
        return myObject == null ? 0 : 1;

    public static final Parcelable.Creator<MyParcelable> CREATOR = new Parcelable.Creator<MyParcelable>() {

        public MyParcelable createFromParcel(Parcel parcel) {
            return new MyParcelable(parcel);

        public MyParcelable[] newArray(int length) {
            return new MyParcelable[length];


This logic is really cool because you are actually passing a reference from activity to activity.

I would advise checking for nulls and if the instanceof Binder is MyBinder!

and to implement this you just...

Send it off

Object myObject = "some object";
MyParcelable myParcelable = new MyParcelable();

intent.putExtra("MyParcelable", myParcelable);

Get it back

myParcelable = (MyParcelable) getIntent().getExtras().getParcelable("MyParcelable");
myObject = myParcelable.getObject();

Heck someone could get all crazy and make this sucker a true generic.

I had always wondered why this can't be as simple as calling into a method of the other activity. I recently wrote a utility library that makes it almost as simple as that. You can check it out here( ).

GNLauncher makes sending objects/data to an Activity from another Activity etc as easy as calling a function in tha Activity with the required data as parameters. It introduces type safety and removes all the hastles of having to serialize, attaching to the intent using string keys and undoing the same at the other end.


Define an interface with the methods you want to call on the Activity to launch.

public interface IPayload {
    public void sayHello(String name, int age);

Implement the above interface on the Activity to launch into. Also notify GNLauncher when the activity is ready.

public class Activity_1 extends Activity implements IPayload {

    protected void onCreate(Bundle savedInstanceState) {
        //Notify GNLauncher when the Activity is ready. 

    public void sayHello(String name, int age) {
        Log.d("gnlib_test", "Hello " + name + "! \nYour age is: " + age);

In the other Activity, get a proxy to the above Activity and call any method with the desired parameters.

public class Activity_2 extends Activity {
    public void onClick(View v) {
        ((IPayload)GNLauncher.get().getProxy(this, IPayload.class, Activity_1.class)).sayHello(name, age);

The first activity will be launched and the method called into with the required parameters.


Please refer to for information on how to add the dependencies.

Pass object from one activity to another activity.

(1) source activity

Intent ii = new Intent(examreport_select.this,

                    (Serializable) your List<ArraList<String>> object here);

(2) destination acitivity

List<ArrayList<String>> aa = (List<ArrayList<String>>) getIntent()

Pass one activity to another:

startActivity(new Intent(getBaseContext(),GetActivity.class).putExtra("passingkey","passingvalue"));

Get values:

String myvalue= getIntent().getExtras("passingkey");

This question is also discussed in another question. Please have a look at a solution to Passing data through intent using Serializable . The main point is about using Bundle object which stores the necessary data inside Intent .

 Bundle bundle = new Bundle();

 bundle.putSerializable(key1, value1);
 bundle.putSerializable(key2, value2);
 bundle.putSerializable(key3, value3);


To extract values:

 Bundle bundle = new Bundle();

 for (String key : bundle.keySet()) {
 value = bundle.getSerializable(key));

Advantage of Serializable is its simplicity. However, you should consider using Parcelable method if you need many data to be transferred, because Parcelable is specifically designed for Android and it is more efficient than Serializable . You can create Parcelable class using:

  1. an online tool - site
  2. a plugin for Android Studio - Android Parcelable code generator

We can pass the object from one activity to another activity:

SupplierDetails poSuppliersDetails = new SupplierDetails();

Inside poSuppliersDetails we have some values. Now I am sending this object to target activity:

Intent iPODetails = new Intent(ActivityOne.this, ActivityTwo.class);
iPODetails.putExtra("poSuppliersDetails", poSuppliersDetails);

How to get this in ACtivityTwo:

private SupplierDetails supplierDetails;
    supplierDetails =(SupplierDetails) getIntent().getSerializableExtra("poSuppliersDetails");



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

// To retrieve object in second Activity

使用gson將您的對象轉換為JSON並通過意向傳遞它。 在新的Activity中將JSON轉換為一個對象。


Gson gson = new Gson();
String myJson = gson.toJson(vp);
intent.putExtra("myjson", myjson);


Gson gson = new Gson();
YourObject ob = gson.fromJson(getIntent().getStringExtra("myjson"), YourObject.class);


Intent intent = new Intent(fromClass.this,toClass.class).putExtra("myCustomerObj",customerObj);


Customer customerObjInToClass = getIntent().getExtras().getParcelable("myCustomerObj");


public class Customer implements Parcelable {

    private String firstName, lastName, address;
    int age;

    /* all your getter and setter methods */

    public Customer(Parcel in ) {
        readFromParcel( in );

    public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
        public LeadData createFromParcel(Parcel in ) {
            return new Customer( in );

        public Customer[] newArray(int size) {
            return new Customer[size];

    public void writeToParcel(Parcel dest, int flags) {


    private void readFromParcel(Parcel in ) {

        firstName = in .readString();
        lastName  = in .readString();
        address   = in .readString();
        age       = in .readInt();

如果您選擇使用Samuh描述的方式,請記住只能發送原始值。 也就是說,可分區的值。 所以,如果你的對象包含複雜的對象,這些將不會遵循。 例如,像位圖,HashMap等變量......這些都很難通過意圖傳遞。

一般來說,我建議你只發送原始數據類型作為額外的東西,比如String,int,boolean等等。在你的情況下,它會是: String fnameString lnameint ageString address

我的觀點:更複雜的對象可以通過實現ContentProviderSDCard等來更好地共享。也可以使用靜態變量 ,但這可能會導致錯誤發生。


您還可以將對象的數據寫入臨時字符串和整數,並將它們傳遞給活動。 當然,這樣,你可以獲得傳輸的數據,但不是對象本身。

但是,如果你只是想顯示它們,而不是在另一種方法或類似的東西中使用這個對象,那應該就足夠了。 我以同樣的方式做到了在另一個活動中顯示來自一個對象的數據。

String fName_temp   = yourObject.getFname();
String lName_temp   = yourObject.getLname();
String age_temp     = yourObject.getAge();
String address_temp = yourObject.getAddress();

Intent i = new Intent(this, ToClass.class);
i.putExtra("fname", fName_temp);
i.putExtra("lname", lName_temp);
i.putExtra("age", age_temp);
i.putExtra("address", address_temp);


您也可以直接將它們傳遞給臨時ivars,但這種方式在我看來更加清晰。 另外,您可以將temp ivars設置為null,以便它們可以更快地被GarbageCollector清除。




String fName = getIntent().getExtras().getInt("fname");


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 = null;
        return data;


IntentHelper.addObjectForKey(obj, "key");


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


最好的方法是在應用程序中有一個類(稱為Control),該類將保存一個類型為“Customer”的靜態變量(在您的情況下)。 初始化活動A中的變量


Control.Customer = CustomerClass;

然後轉到活動B並從Control類中獲取它。 不要忘記在使用變量之後分配一個空值,否則內存將被浪費。





D.可以保存公共數據的類可以命名為Common Utilities。 這取決於你。



A. 數據庫

SQLite是嵌入到Android中的開源數據庫。 SQLite支持標準的關係數據庫功能,如SQL語法,事務和預處理語句。


B. 共享偏好

假設你想存儲用戶名。 所以現在有兩件事情,一個關鍵的用戶名, 值的價值。


 // 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



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

C. 對象序列化


使用Java bean並將其存儲為其字段之一,並使用getter和setter來實現。

JavaBeans是具有屬性的Java類。 將屬性視為私有實例變量。 由於他們是私人的,所以他們可以從課外訪問的唯一途徑就是通過課堂中的方法。 更改屬性值的方法稱為setter方法,並且檢索屬性值的方法稱為getter方法。

public class VariableStorage implements Serializable  {

    private String inString;

    public String getInString() {
        return inString;

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


VariableStorage variableStorage = new VariableStorage();



序列化對象寫入文件後,可以從文件讀取並反序列化。 也就是說,表示對象及其數據的類型信息和字節可用於在內存中重新創建對象。





public class CommonUtilities {

    public static String className = "CommonUtilities";


E. 通過意圖傳遞數據

請參考教程Android - 地塊數據以在使用Parcelable類的活動之間傳遞此數據傳遞選項。

用Serializable實現你的類。 假設這是你的實體類:


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

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

    public double getId() {
        return id;

    public void setId(double id) { = id;

    public String getName() {

    public void setName(String name) { = name;

    private double id;
    private String name;

我們將名為dene從X活動發送到Y活動。 X活動中的某處;

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


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


public class MyClass implements Serializable{
    Here is your instance variable

現在你想在startActivity中傳遞這個類的對象。 只需使用這個:

Bundle b = new Bundle();
b.putSerializable("name", myClassObject);