Question

I'm working on an app which uses a ViewPager with two swiping views (first_page.xml and second_page.xml) and has one activity (activity_main.xml).

When in the main activity class I try to access TextView (which is located in the first_page.xml) using findViewById it can't be found.

This is my activity_main.xml

<RelativeLayout 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" >
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>

This is my first_page.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/someText"
        android:text="example"
        android:textSize="42sp" >
    </TextView>
</LinearLayout>

This is my customPagerAdapter

public class CustomPagerAdapter extends PagerAdapter {

    public Object instantiateItem(View collection, int position) {
    LayoutInflater inflater = (LayoutInflater) collection.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    int resId = 0;
    switch (position) {
    case 0: {
        resId = R.layout.first_page;
        break;
    }
    case 1: {
        resId = R.layout.second_page;
        break;
    }
    }
    View view = inflater.inflate(resId, null);
    ((ViewPager) collection).addView(view, 0);
    return view;
}

@Override
public void destroyItem(View arg0, int arg1, Object arg2) {
    ((ViewPager) arg0).removeView((View) arg2);
}

@Override
public boolean isViewFromObject(View arg0, Object arg1) {
    return arg0 == ((View) arg1);
}

@Override
public Parcelable saveState() {
    return null;
}

@Override
public int getCount() {
    return 2;
}
}

And this is my MainActivity, where I want get the first_page layout, find its TextView called someText, and set a new custom font.

public class MainActivity extends Activity {

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // Create and set adapter
    CustomPagerAdapter adapter = new CustomPagerAdapter();
    ViewPager myPager = (ViewPager) findViewById(R.id.pager);
    myPager.setAdapter(adapter);
    myPager.setCurrentItem(0);

    /*
     *  Here i want to set a new custom font but it seems the someText can't
     *  be found because the Activity searches for it in the 
     *  layout.activity_main and not in the layout.first_page
    */
    TextView textView = (TextView) findViewById(R.id.someText);
    Typeface font = Typeface.createFromAsset(getAssets(), "roboto_thin.ttf");  
    textView.setTypeface(font);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}
}

I'm struggling for two days with this problem.

Any suggestions?

Was it helpful?

Solution

The textview is encapsulated in the container of the fragment. If you get a reference to the correct fragment and get a reference to the container you can call findViewById(R.id.someid).


Sample code:

// TODO cast checks
int item = mViewPager.getCurrentItem();
Fragment frag = (Fragment) mPagerAdapter.getItem(item);
View container = frag.getView();
TextView searchTextView = (TextView) container.findViewById(R.id.someid);

Or is your case:

// TODO add null + cast checks
TextView textView = (TextView) ((Fragment)adapter.getItem(0)).getView().findViewById(R.id.someText);
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