public class MainActivity extends AppCompatActivity {

private ListView lstListView;

//private FragmentManager fragmentManager = getSupportFragmentManager();

private Fragment fragmentOne = new Fragment1();

int currentFragment = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

   /* if(savedInstanceState == null){

        Fragment1 fragment1 = new Fragment1();
        Fragment2 fragment2 = new Fragment2();
        Fragment3 fragment3 = new Fragment3();

        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.content_main, fragment1);
        fragmentTransaction.commit();

    }*/

    lstListView = (ListView)findViewById(R.id.lstListView);

    final String[] lista = new String[]{"Fragment 1", "Fragment 2", "Fragment 3"};

    final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, lista);

    lstListView.setAdapter(adapter);

    lstListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            if( position == 0){

                oneFragment();

            } else if (position == 1){


            } else if (position == 2){


            }
        }
    });


}

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

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}


private void oneFragment() {

    if (currentFragment != 1) {

        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.lnlContent, fragmentOne).commit();
        currentFragment = 1;

    }

}

<LinearLayout
    android:id="@+id/lnlContent"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Testing List View With Fragments"
        android:layout_gravity="center_horizontal"
        android:textSize="20dp"/>

    <ListView
        android:id="@+id/lstListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </ListView>

</LinearLayout>

<LinearLayout
    android:id="@+id/lnlTest"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

</LinearLayout>