Question

How to send HashMap value from one Intent to second Intent?

Also, how to retrieve that HashMap value in the second Activity?

Answer 1

Java’s HashMap class extends the Serializable interface, which makes it easy to add it to an intent, using the Intent.putExtra(String, Serializable) method.

In the activity/service/broadcast receiver that receives the intent, you then call
Intent.getSerializableExtra(String) with the name that you used with putExtra.

For example, when sending the intent:

HashMap<String, String> hashMap = new HashMap<String, String>();
hashMap.put("key", "value");
Intent intent = new Intent(this, MyOtherActivity.class);
intent.putExtra("map", hashMap);
startActivity(intent);

And then in the receiving Activity:

protected void onCreate(Bundle bundle) {
    super.onCreate(savedInstanceState);

    Intent intent = getIntent();
    HashMap<String, String> hashMap = (HashMap<String, String>)intent.getSerializableExtra("map");
    Log.v("HashMapTest", hashMap.get("key"));
}