Calling Activity from Fragment

Question

I have a problem with calling activity from fragment class. More:

XML of adapter's layout:

<TextView
     style="@style/LiHeadLogin"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:foreground="?android:attr/selectableItemBackground"
     android:clickable="true"
     android:onClick="openProfile"
     android:id="@+id/genFrom" />

Code from main activity that calls fragment:

public void openProfile(View v) {
     Fragment_Questions frau = new Fragment_Questions();
     frau.openProfile(v);
}

Code from fragment class:

public void openProfile(View v) {

    View row = (View) v.getParent();

    TextView child2 = (TextView) row.findViewById(R.id.genFromlogin);
    String child3 = child2.getText().toString();

    Intent ini = getActivity().getIntent();
    String c_username = ini.getStringExtra(MainActivity.KEY_USERNAME);
    String c_password = ini.getStringExtra(MainActivity.KEY_PASSWORD);
    Intent ini2 = new Intent(context, User.class);
    ini2.putExtra(MainActivity.KEY_USERNAME, c_username);
    ini2.putExtra(MainActivity.KEY_PASSWORD, c_password);
    ini2.putExtra(MainActivity.KEY_USER, child3);
    getActivity().startActivity(ini2);

}

Errors:

java.lang.IllegalStateException: Could not execute method for android:onClick
...
...
...
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Intent android.support.v4.app.FragmentActivity.getIntent()' on a null object reference

P.S. 1. App opens default activity 2. User calls a new activity with passing intent data 3. New activity calls fragment

The first (main) activity:

Intent intent_settings = getIntent();
            String c_username = intent_settings.getStringExtra(MainActivity.KEY_USERNAME);
            String c_password = intent_settings.getStringExtra(MainActivity.KEY_PASSWORD);
            Intent intent_settings_1 = new Intent(this, NewFeed.class);
            intent_settings_1.putExtra(MainActivity.KEY_USERNAME, c_username);
            intent_settings_1.putExtra(MainActivity.KEY_PASSWORD, c_password);
            intent_settings_1.setFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
            startActivity(intent_settings_1);

Okay, and you should know that all fragments are called by viewpager with tab layout.

@Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:
                Fragment_Home tab1 = new Fragment_Home();
                return tab1;
            case 1:
                Fragment_Questions tab2 = new Fragment_Questions();
                return tab2;
            default:
                return null;
        }
    }

will you add the intent that putStringExtra – Dasser Basyouni Jan 01 '17 at 13:40 — Dasser Basyouni, Jan 01 '17 at 13:40
@DasserBasyouni yes, I've added it – HEISENBERG Jan 01 '17 at 13:44 — HEISENBERG, Jan 01 '17 at 13:44

score 1 · Accepted Answer · answered Jan 01 '17 at 13:55

You can only access the activity with getActivity() between calls to onAttach() and onDetach().

Fragment_Questions itself only seems to serve the purpose to start a new activity, so you could just move all the logic to the click listener of the activity and don't use the fragment at all.

If there's more about the fragment and you're actually planning to add it to the activity sometime in the future it still seems better to have this logic separated from the fragment. You only use getActivity() and magically context in there. You could just make it static and give the activity as parameter instead.

public static void openProfile(Activity activity, View v) {
    View row = (View) v.getParent();

    TextView child2 = (TextView) row.findViewById(R.id.genFromlogin);
    String child3 = child2.getText().toString();

    Intent ini = activity.getIntent();
    String c_username = ini.getStringExtra(MainActivity.KEY_USERNAME);
    String c_password = ini.getStringExtra(MainActivity.KEY_PASSWORD);
    Intent ini2 = new Intent(activity, User.class);
    ini2.putExtra(MainActivity.KEY_USERNAME, c_username);
    ini2.putExtra(MainActivity.KEY_PASSWORD, c_password);
    ini2.putExtra(MainActivity.KEY_USER, child3);
    activity.startActivity(ini2);
}

should you please add some code how to realise it, I've tried, but unsuccessful. — HEISENBERG, Jan 01 '17 at 14:08

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

0

Do you extends Fragment OR FragmetnActivity?

if you extend FragmetnActivity (as i think) then dont use getActivity()

Also add the code for the intent that started your current activity

 Fragment_Questions frau = new Fragment_Questions();
     frau.openProfile(v);

You just created new fragment you didnt attached it to the activity? use FragmentManager.

if you trying to use fragment inside ViewPager use THIS guide

edited May 23 '17 at 12:01

Community

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1

answered Jan 01 '17 at 13:41

yotam hadas

702
3
14

I use just Fragment – HEISENBERG Jan 01 '17 at 13:44
upload the code that you started your current activity with – yotam hadas Jan 01 '17 at 13:45
I use viewpager with tab layout to call fragment – HEISENBERG Jan 01 '17 at 13:52
I would love to help you bro but you give us only small parts of code, we need to see how your layout and entire fragment looks like or we will just keep guessing. – yotam hadas Jan 01 '17 at 13:54
I know thats what I told you. You are making NEW fragment which is NOT attached to the activity, therefor getActivity()= null – yotam hadas Jan 01 '17 at 13:55
So, bro, main activity calls method openProfile inside fragment successfully. Problem is located where calling new intent – HEISENBERG Jan 01 '17 at 13:57
I KNOW its called succefully. but once against getActivity() returns null object. The reason is that the fragment isnt attached to the activity. – yotam hadas Jan 01 '17 at 13:58
So how I must attach it? – HEISENBERG Jan 01 '17 at 14:00
well you said you use viewpager, is the fragment in the viewpager? i will add to the answer link to a related topic – yotam hadas Jan 01 '17 at 14:03
Read the post i linked to in the last line in my answer – yotam hadas Jan 01 '17 at 14:08

score 0 · Answer 3 · answered Jan 01 '17 at 13:49

0

You should add Fragment_Questions to Activity.

For example,In Activity layout:

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".MainActivity" >

     <fragment
         android:id="@+id/fragment_question"
         android:name="com.example.view.Fragment_Questions"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content" />
 </LinearLayout>

In Acitivity.java:

questionFragment = (Fragment_Questions) findViewById(fragment_question);

and then, you can user OnClick Event like this:

questionFragment.openProfile(v);

answered Jan 01 '17 at 13:49

Zhang Ligao

147
1
2
10

I use viewpager with tab layout to call fragment – HEISENBERG Jan 01 '17 at 13:52
Function is calling successfully, problem is inside the method that calls activity – HEISENBERG Jan 01 '17 at 13:54
have you init the ViewPager at Activity? you should give more detail code. – Zhang Ligao Jan 01 '17 at 14:08
yes, I've inited, I've added more code to my question – HEISENBERG Jan 01 '17 at 14:08

score 0 · Answer 4 · answered Jan 01 '17 at 13:53

0

You are getting Null Pointer Exception because your fragment is not attached to Activity. You are just instantiating the fragment and then calling its openProfile(View v) method which is a wrong way to handle events. If you already attached fragment then get the instance of framgent using

questionFragment = (Fragment_Questions) findViewById(fragment_question);

You can read below article on how to communicate from Fragments to activity https://developer.android.com/training/basics/fragments/communicating.html

answered Jan 01 '17 at 13:53

Passiondroid

1,573
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I use viewpager with tab layout to call fragment – HEISENBERG Jan 01 '17 at 13:53
Function is calling successfully, problem is inside the method that calls activity – HEISENBERG Jan 01 '17 at 13:54

score 0 · Answer 5 · answered Jan 01 '17 at 13:55

As I have understanded the steps of the user interferance you have to replace getIntent() in the fragment with the intent that starts it which is intent_settings i think

Also make the that intent static in order to share it

And make if statment in order not to have null exception

if(theIntent.hasPutextra)
{getExtra.....}

Calling Activity from Fragment

5 Answers5