Android: Adding a simple Fragment

Question

I am pretty new to Android Apps, so I hope I can find some help here. I have already searched for my problem in here and found something, but that does not work.

I want to add a Fragment to a FrameLayout but it does not work. My goal ist to create a Frame (/Framework?) that is always present and the user can interact with it and inside this Frame in a specific "window" I want to display pages/fragments, five in total, and beeing able to switch the pages/fragments at any time, so I have an always present Frame and inside this dynamically changing pages. But for now I am stuck at the very beginning with adding a simple fragment to this Frame (which is already working btw.)

This is all the relevant code I hope: The error occurs in the MainActivity.java (getSupportFragmentManager().beginTransaction().add(R.id.mainFrame, homeFragment).commit();) where it tells me:

Error:(25, 55) error: no suitable method found for add(int,HomeFragment) method FragmentTransaction.add(Fragment,String) is not applicable (argument mismatch; int cannot be converted to Fragment) method FragmentTransaction.add(int,Fragment) is not applicable (argument mismatch; HomeFragment cannot be converted to Fragment)

I already tried to cast homeFragment to Fragment, but that did not work.

MainActivity.java

import android.app.FragmentTransaction;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;


public class MainActivity extends FragmentActivity
{
    FragmentTransaction fragmentTransaction;
    HomeFragment homeFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        homeFragment = new HomeFragment();
        **getSupportFragmentManager().beginTransaction().add(R.id.mainFrame, homeFragment).commit();**
}

activity_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    tools:ignore="MergeRootFrame" >

    <FrameLayout
        android:id = "@+id/mainFrame"
        android:layout_width = "match_parent"
        android:layout_height = "match_parent"
        android:layout_marginBottom = "@dimen/bottom_Main_Tabs">
        </FrameLayout>

    [...]

</FrameLayout>

fragment_home.xml

<FrameLayout 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="com.example.HomeFragment"> // it is not really com.example...

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />

</FrameLayout>

HomeFragment.java (everything is autogenerated yet, but I already cut something out)

public class HomeFragment extends Fragment
{
    private OnFragmentInteractionListener mListener;


    public static HomeFragment newInstance()
    {
        HomeFragment fragment = new HomeFragment();
        return fragment; // not really neccessary, because it Have shortened it
    }

    public HomeFragment()
    {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState)
    {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_home, container, false);
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri)
    {
        if (mListener != null)
        {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Activity activity)
    {
        super.onAttach(activity);
        try
        {
            mListener = (OnFragmentInteractionListener) activity;
        }
        catch (ClassCastException e)
        {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach()
    {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener
    {
        // TODO: Update argument type and name
        public void onFragmentInteraction(Uri uri);
    }

}

Can somebody please help me?

John

Answer 1

You're mixing up classes from the support library and the new classes available only to newer versions of the OS.

For example, you import android.app.FragmentTransaction (available for API 11+) but the call to getSupportFragmentManager().beginTransaction() returns android.support.v4.app.FragmentTransaction ...

You need to import android.support.v4.app.FragmentTransaction and make sure that your HomeFragment extends android.support.v4.app.Fragment and not android.app.Fragment.