CODEWITHSUNDEEP
androidandroid-intent
yousafkh
yousafkh

Reputation: 104

How to differentiate between intents, when received by multiple activities

Let say I have 3 Activities, Activity A, Activity B and Activity C.

Activity A and Activity B sends an intent to activity C with let say the following code:

ActivityA sending an intent:

Intent i = new Intent();
i.putExtra("ListName", s);
i.setClass(ActivityA.this, ActivityC.class);
startActivity(i);

ActivityB sending an Intent:

Intent i = new Intent();
i.putExtra("PersonName", s);
i.setClass(Activityb.this, ActivityC.class);
startActivity(i);

How do I know in ActivityC which Intent has been received, because whenever ActivityC is called it will always pass this line of code, either for ActivityA or ActivityB

if(getIntent() != null && getIntent().getExtras() != null)

and then give me NullPointerException on this line of code, if the intent was sent from ActivityB

String s = getIntent().getStringExtra("ListName");

Upvotes: 3

Views: 2652

Answers (4)

anoopg87
anoopg87

Reputation: 82

You need to add one extra value to the intent with the classs name of the calling activity 

Intent intent = new Intent();  
intent.setClass(A.this,MyActivity.class);
intent.putExtra("ClassName","A");  
A.this.startActivity(intent);

Intent intent = new Intent();  
intent.setClass(B.this,MyActivity.class);
intent.putExtra("ClassName","B");  
B.this.startActivity(intent);

Intent intent = new Intent();  
intent.setClass(C.this,MyActivity.class);
intent.putExtra("ClassName","C");  
C.this.startActivity(intent);

And then in MyActivity's onCreate Method

Intent intent = this.getIntent();


 if(intent !=null)
 {
 String clsname= intent.getExtras().getString("ClassName");
 if(clsname.equals("A"))
 {
  //Do Something here...
 }
if(clsname.equals("B"))
{
//Do Something here...
}
if(clsname.equals("C"))
{
 //Do Something here...
}       }



        }
        else
        {
            //do something here
        }

Upvotes: 0

Jas
Jas

Reputation: 3212

Add an extra field for class name in Intent,

In ActivityA,
Intent i = new Intent();
i.putExtra("ListName", s);
i.putExtra("Class","A");
i.setClass(ActivityA.this, ActivityC.class);
startActivity(i);

In ActivityB,

 Intent i = new Intent();
    i.putExtra("PersonName", s);
    i.putExtra("Class","B");
    i.setClass(Activityb.this, ActivityC.class);
    startActivity(i);

In your ActivityC, check the tag "Class" 

String className = getIntent().getStringExtra("Class");
if(className.equals("B"))
{
String s = getIntent().getStringExtra("ListName");
}

Upvotes: 4

An SO User
An SO User

Reputation: 24998

So here is what's happening:

Say activity C was started by activity B. Would there be a string associated with the key named ListName ? No. Hence the null value.

So how do you differentiate between the activities?

One way is to put a field in the intent extras which tell you which activity it is.

The other way is this: 

String s = getIntent().getStringExtra("ListName");
if( s != null ){
  // do what you would do if activity B started activity C
}

Upvotes: 1

Gaurav
Gaurav

Reputation: 3763

Add one more extra with your Intent;

Intent i = new Intent();

i.putExtra("TAG",classname);
i.putExtra("key","value");

Upvotes: 3

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