Android HashMap in Bundle?

Question

The android.os.Message uses a Bundle to send with it's sendMessage-method. Therefore, is it possible to put a HashMap inside a Bundle?

Solution is here: [Android - How to pass HashMap between activities?](http://stackoverflow.com/a/11155142/379693) — Paresh Mayani, Jul 12 '12 at 13:37
possible duplicate of [Android - How to pass HashMap between activities?](http://stackoverflow.com/questions/4992097/android-how-to-pass-hashmapstring-string-between-activities) — Andre Bossard, Nov 21 '12 at 10:19

score 185 · Accepted Answer · edited Dec 13 '16 at 10:50

185

try as:

Bundle extras = new Bundle();
extras.putSerializable("HashMap",hashMap);
intent.putExtras(extras);

and in second Activity

Bundle bundle = this.getIntent().getExtras();

if(bundle != null) {
   hashMap = bundle.getSerializable("HashMap");
}

because Hashmap by default implements Serializable so you can pass it using putSerializable in Bundle and get in other activity using getSerializable

edited Dec 13 '16 at 10:50

James Goodwin

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answered Jul 12 '12 at 13:35

ρяσѕρєя K

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I am getting error when try to serialize the linked hash map Parcel: unable to marshal value com.SGID.DataClass.InvalidSubscriptionReasonsData@41bd2b98 – SweetWisher ツ Oct 04 '13 at 11:48
1

Can i use this method for object which contains primitive data type and array list of another object?? – SweetWisher ツ Oct 05 '13 at 04:18
3

If you are having issues make sure you are using HashMap not Map – Matthew Jun 03 '15 at 13:20
2

you might want to cast the returned serializable object to hashmap by following ways (HashMap) – cammando Mar 10 '17 at 13:32
4

This produces a warning about unchecked cast. Is this safe to ignore? – mitsest Oct 20 '17 at 21:16

AMerle · Answer 2 · 2012-07-12T13:36:26.090

14

According to the doc, Hashmap implements Serializable, so you can putSerializable I guess. Did you try it ?

edited Jul 12 '12 at 13:36

answered Jul 12 '12 at 13:29

AMerle

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score 6 · Answer 3 · answered Aug 23 '16 at 06:06

Please note: If you are using a AppCompatActivity, you will have to call the protected void onSaveInstanceState(Bundle outState) {} (NOT public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {}) method.

Example code...

Store the map:

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putSerializable("leftMaxima", leftMaxima);
    outState.putSerializable("rightMaxima", rightMaxima);
}

And receive it in onCreate:

if (savedInstanceState != null) {
    leftMaxima = (HashMap<Long, Float>) savedInstanceState.getSerializable("leftMaxima");
    rightMaxima = (HashMap<Long, Float>) savedInstanceState.getSerializable("rightMaxima");
}

Sorry if it's some kind of a duplicate answer - maybe someone will find it useful. :)

score 5 · Answer 4 · answered Oct 24 '15 at 18:57

5

If you want to send all the keys in the bundle, you can try

for(String key: map.keySet()){
    bundle.putStringExtra(key, map.get(key));
}

answered Oct 24 '15 at 18:57

Kapil Vats

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I'm curious if there's any reason not to do this? I've not used serialization much, and never bundles (new to android), so I'm curious if this is O(n) and appending to a bundle is effectively O(1) or not. If they're not different in cost, not seeing why you'd bother with serializing it into another map. – Captain Prinny Feb 15 '16 at 23:07
@CaptainPrinny unless the map is the only thing you are mapping to the bundle, you might clobber values and you won't know if a key was part of the original map or just a value stored in the bundle. – Jason Sep 27 '18 at 23:36

Dart · Answer 5 · 2018-01-24T07:22:25.593

  public static Bundle mapToBundle(Map<String, Object> data) throws Exception {
    Bundle bundle = new Bundle();
    for (Map.Entry<String, Object> entry : data.entrySet()) {
        if (entry.getValue() instanceof String)
            bundle.putString(entry.getKey(), (String) entry.getValue());
        else if (entry.getValue() instanceof Double) {
            bundle.putDouble(entry.getKey(), ((Double) entry.getValue()));
        } else if (entry.getValue() instanceof Integer) {
            bundle.putInt(entry.getKey(), (Integer) entry.getValue());
        } else if (entry.getValue() instanceof Float) {
            bundle.putFloat(entry.getKey(), ((Float) entry.getValue()));
        }
    }
    return bundle;
}

score 1 · Answer 6 · edited Aug 28 '19 at 12:57

I am using my kotlin implementation of Parcelable to achieve that and so far it works for me. It is useful if you want to avoid the heavy serializable.

Also in order for it to work, I recommend using it with these

Declaration

class ParcelableMap<K,V>(val map: MutableMap<K,V>) : Parcelable {
    constructor(parcel: Parcel) : this(parcel.readMap(LinkedHashMap<K,V>()))

    override fun writeToParcel(parcel: Parcel, flags: Int) {
        parcel.writeMap(map)
    }

    override fun describeContents(): Int {
        return 0
    }

    companion object CREATOR : Parcelable.Creator<ParcelableMap<Any?,Any?>> {
        @JvmStatic
        override fun createFromParcel(parcel: Parcel): ParcelableMap<Any?,Any?> {
            return ParcelableMap(parcel)
        }
        @JvmStatic 
        override fun newArray(size: Int): Array<ParcelableMap<Any?,Any?>?> {
            return arrayOfNulls(size)
        }
    }

}

Use

write

val map = LinkedHashMap<Int, String>()
val wrap = ParcelableMap<Int,String>(map)
Bundle().putParcelable("your_key", wrap)

read

val bundle = fragment.arguments ?: Bundle()
val wrap = bundle.getParcelable<ParcelableMap<Int,String>>("your_key")
val map = wrap.map

Don't forget that if your map K,V are not parceled by default they must implement Parcelable

Did you try to shorten with @Parcelize? – CoolMind Apr 17 '19 at 16:04 — CoolMind, Apr 17 '19 at 16:04

score 0 · Answer 7 · answered Apr 17 '19 at 16:01

0

In Kotlin:

hashMap = savedInstanceState?.getSerializable(ARG_HASH_MAP) as? HashMap<Int, ValueClass>

putSerializable(ARG_HASH_MAP, hashMap)

answered Apr 17 '19 at 16:01

CoolMind

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Android HashMap in Bundle?

7 Answers7

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