Android如何将listview放入查看寻呼机片段

Posted 2023-04-18

【中文标题】Android如何将listview放入查看寻呼机片段

【英文标题】：Android how to put listview in view pager fragments

【发布时间】：2013-07-12 13:58:11

【问题描述】：

我已经通过在 Eclipse 中使用这个模板使用 viewpager 实现了一个滑动标签应用程序

现在我得到一个像这样扩展 FragmentActivity 的活动

        package com.example.abcd2;

    import java.util.Locale;

    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.app.NavUtils;
    import android.support.v4.view.ViewPager;
    import android.view.Gravity;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;

    public class MainActivity 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;

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

        

        @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.
                if(position==0)

Fragment frag2=new ShowFrag2();
                return frag2;
else

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) 
                Locale l = Locale.getDefault();
                switch (position) 
                case 0:
                    return getString(R.string.title_section1).toUpperCase(l);
                case 1:
                    return getString(R.string.title_section2).toUpperCase(l);
                case 2:
                    return getString(R.string.title_section3).toUpperCase(l);
                
                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() 
            

            @Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
                    Bundle savedInstanceState) 
                View rootView = inflater.inflate(R.layout.fragment_main_dummy,
                        container, false);
                TextView dummyTextView = (TextView) rootView
                        .findViewById(R.id.section_label);
                dummyTextView.setText(Integer.toString(getArguments().getInt(
                        ARG_SECTION_NUMBER)));
                return rootView;
            
        

    

在此，为了在其中一个选项卡中创建一个新片段，我根据 getItem() 方法中的位置使用 if-else，如图所示。 片段 showfrag2 是这个

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class ShowFrag2 extends Fragment 
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
        Bundle savedInstanceState) 
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.frag2, container, false);
    

我的问题是，如何在其中一个片段中创建列表视图。我只想以这种方式使用简单的列表视图

LevelAdapter adapter = new LevelAdapter(this,
            R.layout.list_item, weather_data);


    listView1 = (ListView)findViewById(R.id.listView1);



    listView1.setAdapter(adapter);

但这已经在一个活动中完成了。我如何在上面的片段中使用这样的东西。另外，我不能使用 ListFragment，因为 getView() 方法正在返回一个片段。 请帮助了解如何实现这一点。 谢谢 编辑： 这是我的适配器代码：

    package com.example.abcd3;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class LevelAdapter extends ArrayAdapter<Level> 

     static Context context;
        static int layoutResourceId;   
        static Level data[] = null;

    /*    public LevelAdapter(Context context, int layoutResourceId, Level[] data) 
            super(context, layoutResourceId, data);
            this.layoutResourceId = layoutResourceId;
            this.context = context;
            this.data = data;
        */

        public LevelAdapter(ShowFrag1 showFrag1, int listItem,
                Level[] weather_data) 
            super(context, layoutResourceId, data);
            this.layoutResourceId = layoutResourceId;
            this.context = context;
            this.data = data;

            // TODO Auto-generated constructor stub
        

        public long getItemId(int position) 
            return position;
        

        @Override
        public View getView(int position, View convertView, ViewGroup parent) 
            View row = convertView;
            WeatherHolder holder = null;

            if(row == null)
            
                LayoutInflater inflater = ((Activity)context).getLayoutInflater();
                row = inflater.inflate(layoutResourceId, parent, false);

                holder = new WeatherHolder();
                holder.imgIcon = (ImageView)row.findViewById(R.id.imgIcon);
                holder.txtTitle = (TextView)row.findViewById(R.id.txtTitle);
               // holder.imgIcon2=(ImageView)row.findViewById(R.id.imgIcon2);


                row.setTag(holder);
            
            else
            
                holder = (WeatherHolder)row.getTag();
            

            Level weather = data[position];
            holder.txtTitle.setText(weather.title);
            holder.imgIcon.setImageResource(weather.icon);

            return row;
        

        static class WeatherHolder
        
            ImageView imgIcon;
            TextView txtTitle;
        //    ImageView imgIcon2;
        

【参考方案1】：

确保您在R.layout.frag2 中定义了ListView，并将适配器设置为onCreateView 中的ShowFrag2 中的列表视图。 （类似于它在活动中的完成方式）

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

    View fragmentLayout = inflater.inflate(R.layout.frag2, container, false);

    ListView listView1 = (ListView) fragmentLayout.findViewById(R.id.mylistview);

    LevelAdapter adapter = new LevelAdapter(this, R.layout.list_item, weather_data);
    listView1 = (ListView)findViewById(R.id.listView1);
    listView1.setAdapter(adapter);

    return fragmentLayout;

【讨论】：

谢谢，但是如果我尝试你在片段中所说的，findviewbyid() 和 getlistview() 函数不会出现在可用函数列表中。如果可能的话，你能发布一些示例代码吗？

添加了一个例子，你可以关注它。我没有测试过，但你明白了

我在 inflater 行中得到了一个空指针异常，即使我已经定义了 XML 文件，也在我们创建适配器对象的行中。

请检查更新后的问题。我已经为我的适配器添加了代码，它给出了空指针异常。如果我从适配器的代码中删除“静态”，我在创建适配器对象的行中也会出错。错误在哪里？我收到 nullpointerexception:storage==null

我认为问题在于构造函数与片段不兼容。我该如何纠正？