How could I use the button from in one activity to add to list view in another activity?

Question

I'm a bit confused. Was wondering if you could help. If you need any additional details please let me know. thanks :D

Picture

Answer 1

In your Activity that shows the list of items - you need to add a button (that allows the user to add a new item) - when this button is clicked, you then start the "add item activity" (using startActivityForResult()) as Max suggests. When the user clicks the submit button on the "add item activity" - you then set the results setResult(Activity.RESULT_OK, resultIntentObject) (which will be received back by the activity that shows the list of items in the method onActivityResult(int requestCode, int resultCode, Intent data)). Now, if the user did insert data, you "refresh" the list of items - you do this by calling adapter.notifyDataSetChanged() after inserting the new data.

Let me further suggest that you look at the accepted answer describing how to Add Items to ListView, you can also explore options provided here on how to Dynamically add elements to a listView Android

Answer 2

If you have made the button in some other XML than the main and the onClick method is located in some other Activity than MainActivitythen you need to make an onClick method in the MainActivity and call the method from the other activity in your MainActivity .

Also, worth pointing out it is that you should use RecyclerView instead of ListView . I hope this was of any help. I couldn't exactly make out what you are trying to do and this is how I understood it.

Suppose this is your XML code for the button :

<Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/clearCanvas"
        android:onClick="clearCanvas"
        android:layout_gravity="bottom|center"
        android:text="CLEAR"/>

On this you clearly have set the onClick for the method clearCanvas . Now, this method will be looked for in your mainActivity.

If you have another activity in which the onClick method for the said Button exists, remove the parameters inside the braces of that method.

Example : ActiviyNotMain.java :

//... 
 public void clearCanvas(View v) {
    *do this whatever is here*
}
//... 

Remove View v from here.

MainActivity.java :

//...
  private ActivityNotMain activity;
  //... 
  public void clearCanvas(View v) { 
   activity.clearCanvas();
}
//...

Note : In the MainActivity do not remove View v

I hope this helps.

Answer 3

You can use fragments instead because they provide more flexibility on it. Then the Activity has control of both "Activities" (Fragments) and you can toogle between them with .replace on the FragmentManager. The other thing you can do it's pass the data using parcelable but you have to keep in a database or something the previous items. With fragments you don't need that. If you could provide more information of what exactly you want to do it would be really helpful. Thanks!