title: How to implement button SetOnClickListener in a fragment?
body: <p>I'm working on a small project and I want to use a Slider Menu. Long story short I happen to find a source code of a slider menu using drawer from some website and it works very well on my device. However I'm a little bit confused migrating my previous activity into this slider menu because they use fragment for each individual item on the listView.</p>
  
  <p>To simple things up I want to migrate an activity that capable of do a Ping function. it's xml file consist of one EditText, a Button, and a TextView for showing the output.</p>
  
  <p>Now I did manage to "successfully" migrating that activity into this fragment. The drawer runs well, but I got stuck because the app always force close after I click on the ping button.</p>
  
  <p><strong><em>PS: I haven't change the class name yet, pardon me</em></strong></p>
  
  <p>Below are my code:</p>
  
  <p>this is my original Ping activity:</p>
  
  <pre><code>package my.jlm;
  
  import java.io.IOException;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  
  import android.app.Activity;
  import android.os.Bundle;
  import android.text.Editable;
  import android.util.Log;
  import android.view.View;
  import android.widget.Button;
  import android.widget.EditText;
  import android.widget.TextView;
  
  
  public class Ping extends Activity {
      EditText edit;
      TextView text;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
      // TODO Auto-generated method stub
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_ping);
      edit = (EditText)findViewById(R.id.editText1);
      edit.setText("192.168.1.1");
      text = (TextView)findViewById(R.id.textView1);
      Button button = (Button)findViewById(R.id.button1);
      button.setOnClickListener(new View.OnClickListener() {
  
      @Override
      public void onClick(View v) {
      // TODO Auto-generated method stub
  
      Editable host = edit.getText();
      try {
      String pingCmd = "ping -c 5 " + host;
      String pingResult = "";
      Runtime r = Runtime.getRuntime();
      Process p = r.exec(pingCmd);
      BufferedReader in = new BufferedReader(new
      InputStreamReader(p.getInputStream()));
      String inputLine;
      while ((inputLine = in.readLine()) != null) {
      System.out.println(inputLine);
      text.setText(inputLine + "\n\n");
      pingResult += inputLine;
      text.setText(pingResult);
      }
      in.close();
      }//try
      catch (IOException e) {
      System.out.println(e);
      }
  
  
      }
      });
      }}
  </code></pre>
  
  <p>this FindPeopleFragment.java (this should be the PingFragment.java).
  I thought this was a successful attempt because eclipse didn't show any red mark, but if Im wrong please correct me.</p>
  
  <pre><code>package info.androidhive.slidingmenu;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  
  import android.app.Fragment;
  import android.content.Intent;
  import android.os.Bundle;
  import android.text.Editable;
  import android.view.LayoutInflater;
  import android.view.View;
  import android.view.View.OnClickListener;
  import android.view.ViewGroup;
  import android.widget.Button;
  import android.widget.EditText;
  import android.widget.TextView;
  
  
  public class FindPeopleFragment extends Fragment 
          implements OnClickListener
  {
          EditText edit;
          TextView text;
          Button button;
  
  
  
  
  
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container,
              Bundle savedInstanceState) {
  
          View rootView = inflater.inflate(R.layout.activity_ping, container, false);
  
  
          EditText edit = (EditText) rootView.findViewById(R.id.editText1);
          edit.setText("192.168.1.1");
          text = (TextView) rootView.findViewById(R.id.textView1);
          button = (Button)rootView.findViewById(R.id.button1);
          button.setOnClickListener(onClickListener);
  
  
  
  
  
          return rootView;
      }
  
      @Override
      public void onClick(View v) {
          Editable host = edit.getText();
          try {
          String pingCmd = "ping -c 5 " + host;
          String pingResult = "";
          Runtime r = Runtime.getRuntime();
          Process p = r.exec(pingCmd);
          BufferedReader in = new BufferedReader(new
          InputStreamReader(p.getInputStream()));
          String inputLine;
          while ((inputLine = in.readLine()) != null) {
          System.out.println(inputLine);
          text.setText(inputLine + "\n\n");
          pingResult += inputLine;
          text.setText(pingResult);
          }
          in.close();
          }//try
          catch (IOException e) {
          System.out.println(e);
          }
  
      }
  
  };;
  </code></pre>
  
  <p>and finally this is my Manifest for above project</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="info.androidhive.slidingmenu"
      android:versionCode="1"
      android:versionName="1.0" &gt;
  
      &lt;permission
          android:name="my.jlm.permission.MAPS_RECEIVE"
          android:protectionLevel="signature"/&gt;
  
      &lt;uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/&gt;
      &lt;uses-permission android:name="museumjakarta.source.permission.MAPS_RECEIVE"/&gt;    
      &lt;uses-permission android:name="android.permission.INTERNET"/&gt;
      &lt;uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/&gt;
      &lt;uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/&gt;
      &lt;uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/&gt;
      &lt;uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/&gt;
      &lt;uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/&gt;
      &lt;uses-permission android:name="android.permission.INTERNET"/&gt;
      &lt;uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/&gt;
      &lt;uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/&gt;
  
  
        &lt;uses-permission android:name="android.permission.CALL_PHONE" /&gt;
        &lt;uses-permission android:name="android.permission.READ_PHONE_STATE" /&gt;
  
      &lt;uses-sdk
          android:minSdkVersion="11"
          android:targetSdkVersion="17" /&gt;
  
      &lt;application
          android:allowBackup="true"
          android:icon="@drawable/ic_launcher"
          android:label="@string/app_name"
          android:theme="@style/AppTheme" &gt;
          &lt;activity
              android:name="info.androidhive.slidingmenu.MainActivity"
              android:label="@string/app_name" &gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="android.intent.action.MAIN" /&gt;
  
                  &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;/intent-filter&gt;
          &lt;/activity&gt;
  
  
  
  
      &lt;/application&gt;
  
  &lt;/manifest&gt;
  </code></pre>
  
  <p>and this is my LogCat error log:</p>
  
  <pre><code>03-15 09:07:41.160: E/AndroidRuntime(1267): FATAL EXCEPTION: main
  03-15 09:07:41.160: E/AndroidRuntime(1267): Process: info.androidhive.slidingmenu, PID: 1267
  03-15 09:07:41.160: E/AndroidRuntime(1267): java.lang.NullPointerException
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at info.androidhive.slidingmenu.FindPeopleFragment.onClick(FindPeopleFragment.java:53)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at android.view.View.performClick(View.java:4424)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at android.view.View$PerformClick.run(View.java:18383)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at android.os.Handler.handleCallback(Handler.java:733)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at android.os.Handler.dispatchMessage(Handler.java:95)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at android.os.Looper.loop(Looper.java:137)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at android.app.ActivityThread.main(ActivityThread.java:4998)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at java.lang.reflect.Method.invokeNative(Native Method)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at java.lang.reflect.Method.invoke(Method.java:515)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
  03-15 09:07:41.160: E/AndroidRuntime(1267):     at dalvik.system.NativeStart.main(Native Method)
  </code></pre>
  
  <p>to simplify here is what I experienced:
  the Ping xml page shows up after I click from the Drawer ListView, however when I click the Ping Button inside it, the application crashed, resulting the above error log. Help me resolve this problem and thank you very much.</p>
  
  <p>PS: I'm using eclipse adt because I can't run AS on my AMD processor.</p>
  
  <p>edit: thought it may help, i will post the mainActivity.java for this fragment:</p>
  
  <pre><code>package info.androidhive.slidingmenu;
  
  import info.androidhive.slidingmenu.adapter.NavDrawerListAdapter;
  import info.androidhive.slidingmenu.model.NavDrawerItem;
  
  import java.util.ArrayList;
  
  import android.app.Activity;
  import android.app.Fragment;
  import android.app.FragmentManager;
  import android.content.res.Configuration;
  import android.content.res.TypedArray;
  import android.os.Bundle;
  import android.support.v4.app.ActionBarDrawerToggle;
  import android.support.v4.widget.DrawerLayout;
  import android.util.Log;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.view.View;
  import android.widget.AdapterView;
  import android.widget.ListView;
  
  public class MainActivity extends Activity {
      private DrawerLayout mDrawerLayout;
      private ListView mDrawerList;
      private ActionBarDrawerToggle mDrawerToggle;
  
      // nav drawer title
      private CharSequence mDrawerTitle;
  
      // used to store app title
      private CharSequence mTitle;
  
      // slide menu items
      private String[] navMenuTitles;
      private TypedArray navMenuIcons;
  
      private ArrayList&lt;NavDrawerItem&gt; navDrawerItems;
      private NavDrawerListAdapter adapter;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          mTitle = mDrawerTitle = getTitle();
  
          // load slide menu items
          navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
  
          // nav drawer icons from resources
          navMenuIcons = getResources()
                  .obtainTypedArray(R.array.nav_drawer_icons);
  
          mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
          mDrawerList = (ListView) findViewById(R.id.list_slidermenu);
  
          navDrawerItems = new ArrayList&lt;NavDrawerItem&gt;();
  
          // adding nav drawer items to array
          // Home
          navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
          // Find People
          navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
          // Photos
          navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
          // Communities, Will add a counter here
          navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1), true, "22"));
          // Pages
          navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
          // What's hot, We  will add a counter here
          navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1), true, "50+"));
  
  
          // Recycle the typed array
          navMenuIcons.recycle();
  
          mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
  
          // setting the nav drawer list adapter
          adapter = new NavDrawerListAdapter(getApplicationContext(),
                  navDrawerItems);
          mDrawerList.setAdapter(adapter);
  
          // enabling action bar app icon and behaving it as toggle button
          getActionBar().setDisplayHomeAsUpEnabled(true);
          getActionBar().setHomeButtonEnabled(true);
  
          mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
                  R.drawable.ic_drawer, //nav menu toggle icon
                  R.string.app_name, // nav drawer open - description for accessibility
                  R.string.app_name // nav drawer close - description for accessibility
          ) {
              public void onDrawerClosed(View view) {
                  getActionBar().setTitle(mTitle);
                  // calling onPrepareOptionsMenu() to show action bar icons
                  invalidateOptionsMenu();
              }
  
              public void onDrawerOpened(View drawerView) {
                  getActionBar().setTitle(mDrawerTitle);
                  // calling onPrepareOptionsMenu() to hide action bar icons
                  invalidateOptionsMenu();
              }
          };
          mDrawerLayout.setDrawerListener(mDrawerToggle);
  
          if (savedInstanceState == null) {
              // on first time display view for first nav item
              displayView(0);
          }
      }
  
      /**
       * Slide menu item click listener
       * */
      private class SlideMenuClickListener implements
              ListView.OnItemClickListener {
          @Override
          public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position,
                  long id) {
              // display view for selected nav drawer item
              displayView(position);
          }
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          getMenuInflater().inflate(R.menu.main, menu);
          return true;
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          // toggle nav drawer on selecting action bar app icon/title
          if (mDrawerToggle.onOptionsItemSelected(item)) {
              return true;
          }
          // Handle action bar actions click
          switch (item.getItemId()) {
          case R.id.action_settings:
              return true;
          default:
              return super.onOptionsItemSelected(item);
          }
      }
  
      /* *
       * Called when invalidateOptionsMenu() is triggered
       */
      @Override
      public boolean onPrepareOptionsMenu(Menu menu) {
          // if nav drawer is opened, hide the action items
          boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
          menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
          return super.onPrepareOptionsMenu(menu);
      }
  
      /**
       * Diplaying fragment view for selected nav drawer list item
       * */
      private void displayView(int position) {
          // update the main content by replacing fragments
          Fragment fragment = null;
          switch (position) {
          case 0:
              fragment = new HomeFragment();
              break;
          case 1:
              fragment = new FindPeopleFragment();
              break;
          case 2:
              fragment = new PhotosFragment();
              break;
          case 3:
              fragment = new CommunityFragment();
              break;
          case 4:
              fragment = new PagesFragment();
              break;
          case 5:
              fragment = new WhatsHotFragment();
              break;
  
          default:
              break;
          }
  
          if (fragment != null) {
              FragmentManager fragmentManager = getFragmentManager();
              fragmentManager.beginTransaction()
                      .replace(R.id.frame_container, fragment).commit();
  
              // update selected item and title, then close the drawer
              mDrawerList.setItemChecked(position, true);
              mDrawerList.setSelection(position);
              setTitle(navMenuTitles[position]);
              mDrawerLayout.closeDrawer(mDrawerList);
          } else {
              // error in creating fragment
              Log.e("MainActivity", "Error in creating fragment");
          }
      }
  
      @Override
      public void setTitle(CharSequence title) {
          mTitle = title;
          getActionBar().setTitle(mTitle);
      }
  
      /**
       * When using the ActionBarDrawerToggle, you must call it during
       * onPostCreate() and onConfigurationChanged()...
       */
  
      @Override
      protected void onPostCreate(Bundle savedInstanceState) {
          super.onPostCreate(savedInstanceState);
          // Sync the toggle state after onRestoreInstanceState has occurred.
          mDrawerToggle.syncState();
      }
  
      @Override
      public void onConfigurationChanged(Configuration newConfig) {
          super.onConfigurationChanged(newConfig);
          // Pass any configuration change to the drawer toggls
          mDrawerToggle.onConfigurationChanged(newConfig);
      }
  
  }
  </code></pre>