在我的 android 应用程序中，我正在使用 viewpager。我有两个 fragment 。Fragment1 和 Fragment2。我在两个 fragment 上调用两个不同的函数。即，Fragment1 上的“function1”和 fragment2 上的“function2”。当我启动应用程序时，两者这两个函数一起调用。我想在启动时调用“function1”，仅当我滑动到 Fragment2 时调用“function2”。我该怎么做？提前致谢......

这是我的代码，

fragment 1=>

public class Fragment1 extends Fragment{


    public static String feedurl="http://www.abcd.com/en/rssfeeds/1_2_3_5/latest/rss.xml";
    static String URL = "";
    static final String KEY_HEAD = "item"; // parent node
    static final String KEY_DATE = "pubDate";
    public static String headflag="";
    int f=0;
    GridView list;
        HeadlinesAdapter adapter;
        private TextView mMessageView;
    private Button mClearButton;

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

        View v = inflater.inflate(R.layout.first_fragment, container, false);


        return v;
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);



        function1();//here I am calling function1
        populate_listview();

        }


     public void populate_listview()
     {


         URL="http://www.abcd.com/en/rssfeeds/1_2_3_5/latest/rss.xml";
         ArrayList<HashMap<String, String>> newsList = new ArrayList<HashMap<String, String>>();

        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL);
        Document doc = parser.getDomElement(xml);
        NodeList nl = doc.getElementsByTagName(KEY_HEAD);
        NodeList itemLst = doc.getElementsByTagName("item");
        String MarqueeStr="";

        for (int i = 0; i < nl.getLength(); i++) {
            HashMap<String, String> map = new HashMap<String, String>();
            Element e = (Element) nl.item(i);
                        newsList.add(map);


     }
        list=(GridView)getActivity().findViewById(R.id.grid);
        adapter=new Adapter1(getActivity(), newsList);        
                list.setAdapter(adapter);

      }




}

fragment 2=>

   public class Fragment2 extends Fragment{


    public static String feedurl="http://www.abcd.com/en/rssfeeds/1_2_3_5/latest/rss.xml";
    static String URL = "";
    static final String KEY_HEAD = "item"; // parent node
    static final String KEY_DATE = "pubDate";
    public static String headflag="";
    int f=0;
    GridView list;
    HeadlinesAdapter adapter;
    private TextView mMessageView;
    private Button mClearButton;

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

        View v = inflater.inflate(R.layout.second_fragment, container, false);


        return v;
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);



        function2();//here I am calling function2
        populate_listview();

        }


     public void populate_listview()
     {


         URL="http://www.abcd.com/en/rssfeeds/1_2_3_5/latest/rss.xml";
         ArrayList<HashMap<String, String>> newsList = new ArrayList<HashMap<String, String>>();

        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL);
        Document doc = parser.getDomElement(xml);
        NodeList nl = doc.getElementsByTagName(KEY_HEAD);
        NodeList itemLst = doc.getElementsByTagName("item");
        String MarqueeStr="";

        for (int i = 0; i < nl.getLength(); i++) {
            HashMap<String, String> map = new HashMap<String, String>();
            Element e = (Element) nl.item(i);
                    newsList.add(map);


     }
        list=(GridView)getActivity().findViewById(R.id.grid2);
        adapter=new HeadlinesAdapter(getActivity(), newsList);        
                list.setAdapter(adapter);

      }




}

主要 Activity =>

public class MainActivity extends FragmentActivity {

    private ViewPager mViewPager;
    private MessageLoader mLoader;
    private Button mSenderButton, mReceiverButton;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // We get UI references
        mViewPager = (ViewPager) findViewById(R.id.viewPager);
        mSenderButton = (Button) findViewById(R.id.sender_button);
        mReceiverButton = (Button) findViewById(R.id.receiver_button);
        // set pager adapter
        mViewPager.setAdapter(new MyAdapter(this));
        // set receiver button listener
        mReceiverButton.setOnClickListener(new OnClickListener() {          

            public void onClick(View v) {
                mViewPager.setCurrentItem(1);
            }
        });

        mSenderButton.setOnClickListener(new OnClickListener() {            

            public void onClick(View v) {
                mViewPager.setCurrentItem(0);
            }
        });
    }


    private class MyAdapter extends FragmentPagerAdapter{

        private Context mContext;
        private String[] frags = {Fragment1.class.getName(), Fragment2.class.getName()};

        public MyAdapter(FragmentActivity activity) {
            super(activity.getSupportFragmentManager());
            mContext = activity;
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            Fragment frag = (Fragment) super.instantiateItem(container, position);
            if(frag instanceof MessageLoader){
                mLoader = (MessageLoader) frag;
            }
            return frag;
        }

        @Override
        public Fragment getItem(int pos) {
            return Fragment.instantiate(mContext, frags[pos]);
        }

        @Override
        public int getCount() {
            return frags.length;
        }

    }




}

这是布局，

first_fragment.xml =>

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#ffff"
    android:orientation="vertical" >



    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >



    </RelativeLayout>

    <GridView
        android:id="@+id/grid"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:numColumns="2" >
    </GridView>

</LinearLayout>

second_fragment.xml =>

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#ffff"
    android:orientation="vertical" >



    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >



    </RelativeLayout>

    <GridView
        android:id="@+id/grid2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:numColumns="2" >
    </GridView>

</LinearLayout>

main.xml=>

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#CCCCCC"
        android:gravity="center_vertical"
        android:paddingTop="3dp" >

        <Button
            android:id="@+id/receiver_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Headlines" />

        <Button
            android:id="@+id/sender_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Kerala" />
    </TableRow>

    <android.support.v4.view.ViewPager
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

最佳答案

您可以使用以下代码捕获滑动事件:

mViewPager.setOnPageChangeListener(new OnPageChangeListener() {

@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) 
{

}

@Override
public void onPageSelected(int position) {
       if(position==0){
        function1();
       }else if(position==1){
        function2();
       }

}

@Override
public void onPageScrollStateChanged(int state) {

}
});

在任何最适合的覆盖方法中调用您的函数

关于android - 在 Android 的 fragment 中调用函数，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13373930/