title: How can I access a Button on a fragment?
body: <p>How do I access a button that is on a fragment and program click events. I know there are similar questions to this, however I have tried the solutions they have given and they did not work for me. I always get the unreachable error. </p>
  
  <p>Requirement; Basically I have two buttons in the XML, one is visible the other is not. I am trying to click on the visible button, making it invisible, then making the previously invisible one, visible.</p>
  
  <p>Please note, the fragments are being made by editing Android Studios default navaigation drawer activity
  I am trying to have a universal navigation drawer. Easier to edit the default class.</p>
  
  <p>Activity Code</p>
  
  <pre><code>package co.timetrax.drawer;
  
  import android.os.Bundle;
  import android.support.design.widget.FloatingActionButton;
  import android.support.design.widget.Snackbar;
  import android.view.View;
  import android.support.design.widget.NavigationView;
  import android.support.v4.view.GravityCompat;
  import android.support.v4.widget.DrawerLayout;
  import android.support.v7.app.ActionBarDrawerToggle;
  import android.support.v7.app.AppCompatActivity;
  import android.support.v7.widget.Toolbar;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.widget.Button;
  
  import butterknife.Bind;
  import butterknife.ButterKnife;
  
  public class MainActivity extends AppCompatActivity
          implements NavigationView.OnNavigationItemSelectedListener {
  
      NavigationView navigationView = null;
      Toolbar toolbar = null;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          //setting fragments
          MainFragment fragment = new MainFragment();
          android.support.v4.app.FragmentTransaction fragmentTransaction =
                  getSupportFragmentManager().beginTransaction();
          fragmentTransaction.replace(R.id.fragment_container, fragment);
          fragmentTransaction.commit();
  
          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();
              }
          });
  
          DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
          ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                  this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
          drawer.setDrawerListener(toggle);
          toggle.syncState();
  
          navigationView = (NavigationView) findViewById(R.id.nav_view);
          navigationView.setNavigationItemSelectedListener(this);
  
      }
  
      @Override
      public void onBackPressed() {
          DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
          if (drawer.isDrawerOpen(GravityCompat.START)) {
              drawer.closeDrawer(GravityCompat.START);
          } else {
              super.onBackPressed();
          }
      }
  
      @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;
      }
  
      @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);
      }
  
      @SuppressWarnings("StatementWithEmptyBody")
      @Override
      public boolean onNavigationItemSelected(MenuItem item) {
          // Handle navigation view item clicks here.
          int id = item.getItemId();
  
          if (id == R.id.nav_camera) {
              // Handle the camera action
              MainFragment fragment = new MainFragment();
              android.support.v4.app.FragmentTransaction fragmentTransaction =
                      getSupportFragmentManager().beginTransaction();
              fragmentTransaction.replace(R.id.fragment_container, fragment);
              fragmentTransaction.commit();
          } else if (id == R.id.nav_gallery) {
  
          } else if (id == R.id.nav_slideshow) {
  
          } else if (id == R.id.nav_manage) {
  
          } else if (id == R.id.nav_share) {
  
          } else if (id == R.id.nav_send) {
  
          }
  
          DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
          drawer.closeDrawer(GravityCompat.START);
          return true;
      }
  }
  </code></pre>
  
  <p>Fragment Code</p>
  
  <pre><code>package co.timetrax.drawer;
  
  
  import android.os.Bundle;
  import android.support.v4.app.Fragment;
  import android.view.LayoutInflater;
  import android.view.View;
  import android.view.ViewGroup;
  import android.widget.Button;
  
  import butterknife.Bind;
  import butterknife.ButterKnife;
  
  
  
  /**
   * A simple {@link Fragment} subclass.
   */
  public class MainFragment extends Fragment implements View.OnClickListener {
  
      public MainFragment() {
          // Required empty public constructor
      }
  
  
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
                               Bundle savedInstanceState) {
          // Inflate the layout for this fragment
          return inflater.inflate(R.layout.fragment_main, container, false);
  
      }
  
      @Override
      public void onClick(View v) {
  
      }
  
  }
  </code></pre>
  
  <p>Here is the fragment xml;</p>
  
  <pre><code>&lt;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="co.timetrax.drawer.MainFragment"&gt;
  
      &lt;Button
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="MAIN"
          android:padding="8dp"
          android:textColor="#fff"
          android:background="@color/colorPrimary"
          android:textSize="28sp"
          android:id="@+id/main_button"
          android:layout_centerVertical="true"
          android:layout_centerHorizontal="true" /&gt;
  
      &lt;Button
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="second"
          android:visibility="gone"
          android:padding="8dp"
          android:textColor="#fff"
          android:background="@color/colorPrimary"
          android:textSize="28sp"
          android:id="@+id/second_button"
          android:layout_centerVertical="true"
          android:layout_centerHorizontal="true" /&gt;
  
  
  &lt;/RelativeLayout&gt;
  </code></pre>