Start Activity from Non-Activity

Question

I have an Activity class.

public class A extends Activity
{
}

Then I have a class that is not an Activity but I want it to start the Activity A.

public class B
{
    public B()
    {
       Intent I = new Intent(null, A.class);
       i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    }
}

The code is take from this question which should work: Calling startActivity() from outside of an Activity? However, when I run it I never change from my first activity to activity A. What am I doing wrong? Should I be listening to the FLAG_ACTIVITY_NEW_TASK inside A?

you must have a context to start an Activity. If you have a context then you can start activity from almost every point — Illegal Argument, Sep 05 '14 at 02:57
startActivity can't be called inside of `B` because `B` is not an Activity. @IllegalArgument can you explain context? — Mike John, Sep 05 '14 at 02:58
@MikeJohn you can use startActivity in your class b but you need a valid context to do so. context.startActivity(intent); — Illegal Argument, Sep 05 '14 at 03:00
@IllegalArgument How do I get this valid context? Is it a reference to class A? — Mike John, Sep 05 '14 at 03:02

Illegal Argument · Accepted Answer · 2014-09-05T03:27:48.783

4

Something like this should work:

public class B {
Context context;

public B(Context context) {
    this.context = context;

}

public void startNewActivity(String str) {
    try {
        Intent i = new Intent(context, Class.forName(str));
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(i);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
}
}

Use case of class B:

    B b = new B(A.this);
    b.startNewActivity("MainActivity");//the "MainActivity" is the className of the java class

Note I find this way wierd and a overkill.

edited Sep 05 '14 at 03:27

answered Sep 05 '14 at 03:04

Illegal Argument

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I might be able to use it if this line `A.class` can be something more generic that would work for other activities. Maybe using `context.class` (that would probably fail.) – Mike John Sep 05 '14 at 03:08

Start Activity from Non-Activity

1 Answers1