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我在android SDK中找到了ViewPager，并且正在搞乱它。基本上我最后的任务是在一个应用程序中创建一个youtube，facebook和twitter feed，使用ViewPager和Fragments在3个类别之间滚动。我有点难以理解这些工作，更具体地说，我如何添加一个元素（按钮）到特定的片段？这里是我到目前为止的代码：将按钮添加到ViewPager中的特定片段
package com.ito.mindtrekkers;
import java.util.ArrayList;
import twitter4j.Query;
import twitter4j.QueryResult;
import twitter4j.Twitter;
import twitter4j.TwitterException;
import twitter4j.TwitterFactory;
import android.annotation.SuppressLint;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.TextView;
import android.widget.Toast;
@SuppressLint("ShowToast")
//Brady Mahar
public class Main extends FragmentActivity {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
* will keep every loaded fragment in memory. If this becomes too memory
* intensive, it may be best to switch to a
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
ArrayList<String> tweetList = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
mViewPager.setCurrentItem(1); //sets initial page to "Facebook"
new DownloadFilesTask().execute("weather" , null, null);
}
@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;
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@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.
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
fragment.setArguments(args);
return fragment;
}
@Override
public int getCount() {
// Show 3 total pages.
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return getString(R.string.title_youtube);
case 1:
return getString(R.string.title_facebook);
case 2:
return getString(R.string.title_twitter);
}
return null;
}
}
/**
* A dummy fragment representing a section of the app, but that simply
* displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
public static final String ARG_SECTION_NUMBER = "section_number";
public DummySectionFragment() {
}
@SuppressLint("ShowToast")
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Create a new TextView and set its text to the fragment's section
// number argument value.
TextView textView = new TextView(getActivity());
textView.setGravity(Gravity.CENTER);
textView.setText(Integer.toString(getArguments().getInt(ARG_SECTION_NUMBER)));
return textView;
}
}
/**
* Class for handling NetworkOnMainThread
* Sends the command Asynchronously
* @author austinn
*
*/
private class DownloadFilesTask extends AsyncTask<String, Void, String> {
protected String doInBackground(String... command) {
Twitter twitter = new TwitterFactory().getInstance();
Query query = new Query("from:MindTrekkers");
query.setRpp(100);
try {
QueryResult result = twitter.search(query);
for(twitter4j.Tweet tweet : result.getTweets()) {
//Toast.makeText(getApplicationContext(), tweet.getText(), Toast.LENGTH_SHORT);
Log.v("Tweet", tweet.getText());
tweetList.add(tweet.getText());
}
} catch (TwitterException e) {
//Toast.makeText(getApplicationContext(), e + "", Toast.LENGTH_SHORT);
Log.v("Error", e+"");
}
return null;
}
protected void onProgressUpdate(Void... progress) {}
protected void onPostExecute(String result) {}
}
}