如何从片段开始活动

Question

我有2个片段，InboxFragment和FriendsFragment，当我按下FriendsFragment并选择我的一个朋友时，我想开始一个新的Activity。但我无法让它发挥作用。

UserListActivity

公共类UserListActivity扩展了Activity {

public static final String user = null;

/** The Chat list. */
private ArrayList<ParseUser> uList;

/** The user. */
public static ParseUser Username; 

/* (non-Javadoc)
 * @see android.support.v4.app.FragmentActivity#onCreate(android.os.Bundle)
 */
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.user_list);

    getActionBar().setDisplayHomeAsUpEnabled(false);

    updateUserStatus(true);
}

/* (non-Javadoc)
 * @see android.support.v4.app.FragmentActivity#onDestroy()
 */
@Override
protected void onDestroy()
{
    super.onDestroy();
    updateUserStatus(false);
}

/* (non-Javadoc)
 * @see android.support.v4.app.FragmentActivity#onResume()
 */
@Override
protected void onResume()
{
    super.onResume();
    loadUserList();

}

/**
 * Update user status.
 * 
 * @param online
 *            true if user is online
 */
private void updateUserStatus(boolean online)
{
    user();
    user();
}

private void user() {
    // TODO Auto-generated method stub

}

/**
 * Load list of users.
 */
private void loadUserList()
{
    final ProgressDialog dia = ProgressDialog.show(this, null,
            getString(R.string.alert_loading));
    ParseUser.getQuery().whereNotEqualTo("username", Username.getUsername())
            .findInBackground(new FindCallback<ParseUser>() {

                @SuppressWarnings("unused")
                public void done(List<ParseUser> li, ParseException e)
                {
                    dia.dismiss();
                    if (li != null)
                    {
                        if (li.size() == 0)
                            Toast.makeText(UserListActivity.this,
                                    R.string.msg_no_user_found,
                                    Toast.LENGTH_SHORT).show();

                        uList = new ArrayList<ParseUser>(li);
                        ListView list = (ListView) findViewById(R.id.list);
                        list.setAdapter(new UserAdapter());
                        list.setOnItemClickListener(new OnItemClickListener() {

                            public void onItemClick(AdapterView<?> arg0,
                                    View arg1, int pos, long arg3)
                            {
                                startActivity(new Intent(UserListActivity.this,
                                        Chat.class).putExtra(
                                        Const.EXTRA_DATA, uList.get(pos)
                                                .getUsername()));
                            }
                        });
                    }
                    else
                    {
                        Utils.showDialog(
                                UserListActivity.this,
                                getString(R.string.err_users) + " "
                                        + e.getMessage());
                        e.printStackTrace();
                    }
                }

                @Override
                public void done(List<ParseUser> arg0,
                        com.parse.ParseException arg1) {
                    // TODO Auto-generated method stub

                }
            });
}

/**
 * The Class UserAdapter is the adapter class for User ListView. This
 * adapter shows the user name and it's only online status for each item.
 */
private class UserAdapter extends BaseAdapter
{

    /* (non-Javadoc)
     * @see android.widget.Adapter#getCount()
     */
    public int getCount()
    {
        return uList.size();
    }

    /* (non-Javadoc)
     * @see android.widget.Adapter#getItem(int)
     */
    public ParseUser getItem(int arg0)
    {
        return uList.get(arg0);
    }

    /* (non-Javadoc)
     * @see android.widget.Adapter#getItemId(int)
     */
    public long getItemId(int arg0)
    {
        return arg0;
    }

    /* (non-Javadoc)
     * @see android.widget.Adapter#getView(int, android.view.View, android.view.ViewGroup)
     */
    @SuppressLint("InflateParams") public View getView(int pos, View v, ViewGroup arg2)
    {
        if (v == null)
            v = getLayoutInflater().inflate(R.layout.chat_item, null);

        ParseUser c = getItem(pos);
        TextView lbl = (TextView) v;
        lbl.setText(c.getUsername());
        lbl.setCompoundDrawablesWithIntrinsicBounds(
                c.getBoolean("online") ? R.drawable.ic_online
                        : R.drawable.ic_offline, 0, R.drawable.arrow, 0);

        return v;
    }

}

}

SectionsPagerAdapter

公共类SectionsPagerAdapter扩展了FragmentPagerAdapter {

protected Context mContext;

public SectionsPagerAdapter(Context context, FragmentManager fm) {
    super(fm);
    mContext = context;
}


@Override
public Fragment getItem(int position) {
    // getItem is called to instantiate the fragment for the given page.
    // Return a DummySectionFragment (defined as a static inner class
    // below) with the page number as its lone argument.

    switch(position) {
        case 0:
            return new InboxFragment();
        case 1:
            return new FriendsFragment();
    }

    return null;
}

@Override
public int getCount() {
    return 2;
}

@Override
public CharSequence getPageTitle(int position) {
    Locale l = Locale.getDefault();
    switch (position) {
    case 0:
        return mContext.getString(R.string.title_section1).toUpperCase(l);
    case 1:
        return mContext.getString(R.string.title_section2).toUpperCase(l);
    }
    return null;
}

public int getIcon(int position) {
    switch (position) {
    case 0:
        return R.drawable.ic_tab_inbox;
    case 1:
        return R.drawable.ic_tab_friends;
    }

    return R.drawable.ic_tab_inbox;
}

}

Answer 1

尝试以这种方式启动Activity：

Intent intent = new Intent(getActivity(), ActivityToStart.class);
intent.putExtra(Const.EXTRA_DATA, uList.get(pos).getUsername());
getActivity().startActivity(intent);