Oto mój kod:

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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >



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



</RelativeLayout>

fragment_view1.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/viewOneText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="92dp"
        android:layout_marginTop="182dp"
        android:text="First View"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button
        android:id="@+id/viewOneBtn"
        style="?android:attr/buttonStyleSmall"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/viewOneText"
        android:layout_below="@+id/viewOneText"
        android:layout_marginTop="17dp"
        android:text="Click Here" />

  <include layout = "@layout/drop_down"
            android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dp"
        android:layout_alignParentBottom="true"/>
</RelativeLayout>

custom_view.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="174dp"
        android:text="Custom Fragment"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>

MainActivity.java

package com.example.fragmenttest;

import android.os.Bundle;
import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends  FragmentActivity  {

    private ViewPager viewPager;
    private MyAdapter pageAdapter;
    private static final int ITEMS = 2;

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

        viewPager = (ViewPager)findViewById(R.id.pager);
        pageAdapter = new MyAdapter(getSupportFragmentManager());
        viewPager.setAdapter(pageAdapter);

    }

    @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;
    }

    public static class MyAdapter extends FragmentPagerAdapter {


        public MyAdapter(FragmentManager fragmentManager) {
            super(fragmentManager);
        }

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

        @Override
        public Fragment getItem(int position) {
            if(position==0)
            {
                return new FirstView();
            }
            else
            {
                return new SecondView();
            }
        }
    }

    public void setCurrentItem (int item, boolean smoothScroll) {
        viewPager.setCurrentItem(item, smoothScroll);
    }

public void onMenuItemClicked(View view) {
        Toast.makeText(this, "LOL", Toast.LENGTH_LONG).show();
    }

}

FirstView.java

package com.example.fragmenttest;

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

public class FirstView extends DropDownMenu
{
    private TextView firstText;
    private Button btn;

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {


        View view = inflater.inflate(R.layout.fragment_view1,container,false);


        firstText = (TextView)view.findViewById(R.id.viewOneText);
        btn = (Button)view.findViewById(R.id.viewOneBtn);

        btn.setOnClickListener(new ButtonEvent());
        return view;

    }

    private class ButtonEvent implements OnClickListener
    {


    }


}

CustomView.java

package com.example.fragmenttest;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

public class CustomView extends Fragment
{
    private TextView secondText;
    private Button secondViewBtn;

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

        return view;

    }


}

Kiedy klikam przyciskfragment_view1.xml, Muszę iść docustom_view.xml ekran. To zupełnie inny fragment. Jak mogę to zrobić?