Change Fragment dynamic

Question

I have 2 questions. First, can me say someone, why this not works? I just try to change the fragment, but he does nothing. I just see the first fragment.

mainActivity:

...
if (savedInstanceState == null) {
        fm.beginTransaction()
                .add(R.id.firstFragment, new firstFragment()).commit(); 
    }

    findViewById(R.id.button1).setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            switchFragment(R.id.firstFragment, new firstFragment());
        }
    });

    findViewById(R.id.button2).setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            switchFragment(R.id.secondFragment, new secondFragment());
        }
    });

}

private void switchFragment(int fragId, Fragment frag){
     FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
     ft.replace(fragId, frag);
     ft.commit();
}

Fragments like this in the main.xml:

<Fragment
    android:id="@+id/firstFragment"
    android:name="com.example.firstFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_above="@+id/View01"
    android:layout_below="@+id/view1" />

Fragmentclass just have this:

    @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
      Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_clublist, container, false);

    return view;
  }

And a Fragment just look like this:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Fragment1"
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:textColor="#FFFF0000"/>

I don't know, why he does not change the fragment. A check, that switchFragment really calling is true.

Second question is: Is this a good way to change fragments? What is, if i have 10 fragments?

Thanks for your help! :)

Answer 1

int fragId

should be the id of the container that hosts the Fragment, not the id of the fragment itself