Getting nullpointer when hide androic activity control form fragment class

Question

i want to hide my layout which is in activity class and its visibilty handle in fragmetn class below is my code

Myfragment.java

Tags.mStringVarientSoldOut="yes";
ActivityDetailTest site = new ActivityDetailTest();
site.isSoldOut();

ActivityDetailTest.java

mLinearLayoutBottom is already declared in my onCreate() method of activity class

public void isSoldOut()
{


    if (Tags.mStringVarientSoldOut.equalsIgnoreCase("yes"))
    {
        mLinearLayoutBottom.setVisibility(View.GONE);
    }
    else
    {
        mLinearLayoutBottom.setVisibility(View.VISIBLE);
    }
}

when I run above code i m getting nullpointer error at line mLinearLayoutBottom.setVisibility(View.GONE);
any idea how can i solve this? your all suggestions are appreciable

mLinearLayoutBottom is defined in activity class so how can you call it in fragment ? where are you getting reference of it in fragment ? — Khizar Hayat, Jun 14 '16 at 04:49

score 0 · Answer 1 · answered Jun 14 '16 at 04:55

0

If mLinearLayoutBottom is declared in ActivityDetailTest with public visibility then use it as in Fragment :

ActivityDetailTest objActivity = (ActivityDetailTest) getActivity();
objActivity.mLinearLayoutBottom.setVisibility(View.GONE);

answered Jun 14 '16 at 04:55

ρяσѕρєя K

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ρяσѕρєя K: yes working!! – Jun 14 '16 at 05:00
Rly bad practice. You shouldn't change activity's field from outside. – Stas Lelyuk Jun 14 '16 at 14:22

score 0 · Answer 2 · edited May 23 '17 at 12:01

The perfect way of activity and fragment communication via Interface.

You should declare a interface and implement it in your activity. Then from your fragment you can send command via that interface.

Here is code example, Your interface is:

public interface IActivityController{
void hideOrVisibleView(boolean action);
}

Now, implement this interface in your activity. After implementing this interface, your activity code will like this:

@Override
public void hideOrVisibleView(boolean isHide) {

    if(isHide){
      mLinearLayoutBottom.setVisibility(View.GONE); 
      }else{
        mLinearLayoutBottom.setVisibility(View.VISIBLE); 
       }
}

Now, in your fragment based on your code logic just use this line to hide/visible your View in activity.

((IActivityController)getActivity()).hideOrVisibleView(true/false);

here, if you send true, view will hide and if false then view will visible.

I think, this will the best solution. Hope this will help you.

My related answer is here and here

Thanks, brother. If you think, this is the best solution then mark it as best answer :) . — Md. Sajedul Karim, Jun 14 '16 at 06:04

Harshal Kalavadiya · Answer 3 · 2016-06-14T06:09:17.883

0

Without interface you can also handle by this way

pass Linearlayout object in fragment class constructor from your activity class

MyFragment mMyframge=new MyFragment(mlinearLayoutBottom);

MyFragment.java

create constructor

@SuppressLint("ValidFragment")
public MyFragment (LinearLayout mLinearLayout){
    this.mLinearLayout=mLinearLayout;
}

and now handle your condition in fragment class

if (Tags.mStringVarientSoldOut.equalsIgnoreCase("yes"))
{
    mLinearLayout.setVisibility(View.GONE);
}
else
{
    mLinearLayout.setVisibility(View.VISIBLE);
}

edited Jun 14 '16 at 06:09

answered Jun 14 '16 at 06:08

Harshal Kalavadiya

2,412
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Harshal Kalavadiya : ya working!! – Jun 14 '16 at 06:08
Thanks for your answer. But here has some problem: To pass value via Constructor in fragment, it will show error message when generate release APK. If there has another efficient way to do this things, why you pass a View to another class? – Md. Sajedul Karim Jun 14 '16 at 06:15
Md. Sajedul Karim: i also release APK with same code in my other project and in my case it is working fine – Harshal Kalavadiya Jun 14 '16 at 07:49

Getting nullpointer when hide androic activity control form fragment class

3 Answers3