setOnClickListener中的startActivity onClick on fragment

Question

我的问题是不能在片段中启动我的新活动 请帮帮我为什么？ 我的主要活动是：

package com.slidingmenunav;

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;

import com.slidingmenunav.adapter.NavDrawerListAdapter;
import com.slidingmenunav.model.NavDrawerItem;

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<NavDrawerItem> 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<NavDrawerItem>();

    // 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<?> 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);
  }

}

我的第一个displayView（0）片段，当点击开始新活动时，其中有一个按钮：

package com.slidingmenunav;

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

public class HomeFragment extends Fragment implements View.OnClickListener {

   public HomeFragment(){}

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

    View rootView = inflater.inflate(R.layout.fragment_home, container, false);

    Button b1 = (Button) rootView.findViewById(R.id.button1);

    b1.setOnClickListener(this);

    return rootView;
  }

  @Override
  public void onClick(View v) {

    startActivity(new Intent(getActivity(), Doa.class));
  }
}

和Doa.java：

package com.slidingmenunav;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;

public class Doa extends Activity {

   // List view
   private ListView lv;

   // Listview Adapter
   ArrayAdapter<String> adapter;

   // Doa EditText
   EditText inputSearch;


  // ArrayList for Listview
  ArrayList<HashMap<String, String>> productList;

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

    // Listview Data
    String products[] = getResources().getStringArray(R.array.doa);

    lv = (ListView) findViewById(R.id.list_view);
    inputSearch = (EditText) findViewById(R.id.inputSearch);

    // Adding items to listview
    adapter = new ArrayAdapter<String>(this, R.layout.list_item, R.id.subject_name, products);
    lv.setAdapter(adapter);

    /**
     * Enabling Doa Filter
     * */
    inputSearch.addTextChangedListener(new TextWatcher() {

        @Override
        public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
            // When user changed the Text
            Doa.this.adapter.getFilter().filter(cs);
        }

        @Override
        public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                int arg3) {
            // TODO Auto-generated method stub

        }

        @Override
        public void afterTextChanged(Editable arg0) {
            // TODO Auto-generated method stub                          
        }
    });

    // after click
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, final View view,
            int position, long id) {

            final String item = lv.getItemAtPosition(position).toString();
            int total_number = 3;
            for(int x = 1; x < total_number+1; x = x+1) {
                String SubjectName = "subject_" + String.valueOf(x);
                int resID = getResources().getIdentifier(SubjectName, "string", getPackageName());
                String subject = getResources().getString(resID);

                if(item.equals(subject)) {
                    String StringClass = "com.Subject_" + String.valueOf(x);
                    Class<?> c = null;
                    if(StringClass != null) {
                        try {
                            c = Class.forName(StringClass);
                        } catch (ClassNotFoundException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                    Intent intent = new Intent(Doa.this, c);
                    startActivity(intent);
                }
            }

        }

      });
}

@Override
public void onResume() {
    super.onResume();
    adapter.notifyDataSetChanged();
}

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main, menu);
        return true;
  }

}