getIntentExtra returns default value

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getIntentExtra returns default value

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Hello everyone I am new to android and I am trying to pass an integer from activity A to B and I do it in the following way:

Intent intent = new Intent(this, newClass.class); intent.putExtra("entero1", 5); startActivity(intent);

And in activity B I try to receive the value 5 in this way:

Intent intent = getIntent(); int activityValue = intent.getIntExtra("entero1", 0);

By doing this I always return the default value, in this case the 0 and what I want is to receive the 5 that was put in the putExtra . Can someone explain to me why this happens?

UPDATE:

I have found how to make the getIntExtra return the desired value. Here's my example:
First in the activity class "A" I declare a global variable

public static final String rack_number = "com.engeimanga.smartrack.racknumber";

(The value of this string is given by: (your domain). (the name of your app). (the name you want)

When I create the intent and I do the putExtra I send the name of the global variable and the value I want to send to activity "B"

Intent intent = new Intent(this, newClass.class);
intent.putExtra(rack_number, 5);
startActivity(intent);

Within activity "B" to receive the value correctly I do the following:

Intent intent = getIntent();
int number;
number = intent.getIntExtra(LoginScreen.rack_number, 0);

Doing this in the variable number is already saved the value that was sent from activity "A" The first argument of getIntExtra is: (the name of the activity from which they send the extra). (the name of the variable global that we created).
All this I did based on an example of the android developers page.

To be honest I do not understand very well why it works in this way and not as I had previously if someone could explain it to me I would appreciate it. Meanwhile here is a way to do it.
Greetings

android

asked by Kuii Maldonado 11.03.2018 в 18:36

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2 answers

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You can validate first if you really receive a bundle with information:

   Bundle extras = getIntent().getExtras();
    if (extras != null) {
      //Contiene información.
    }

If the bundle contains information, then verify that the values you want to obtain actually exist:

   int number;
   Bundle extras = getIntent().getExtras();
    if (extras != null) {
      //Contiene información.

        if (extras.containsKey("entero1")) {
            number = extras.getInt("entero1");
        }

    }

answered by 12.03.2018 в 16:11

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score 1 · Accepted Answer

It is always good to verify the non-nullity of the past data in Intent for various reasons:

because a null value may be happening for any reason beyond our control
because we can have Activitys that in some scenarios need extra data, but in others not
etc

To handle any of these possible situations, you can use a ternary operator to verify if a null value is not being passed in Intent . In this way, the ternary operator will assign to the variable either the value passed in Intent , or a default value ( 0 in this case).

To do this, in the onCreate of the Activity that will receive the data, you can put this:

int activityValue = (this.getIntent().getExtras() != null) ? getIntent().getIntExtra("entero1") : 0;.

The value of activityValue will have: or the number that is passed in Intent or 0 in case no value has been passed.