介绍Fragment、ListView、ViewPager三者用法

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一、fragment:碎片化组件,依托Activity存在,不能单独存在。它有十一个生命周期
onAttach                 ()Fragment被附加到Activity的时,调用此函数,在这个方法中可以获得宿主Activity。
onCreate                ()Fragment被创建的时,调用此函数。
onCreateView         ()Fragment的布局加载时,调用此函数。
onActivityCreated   ()当宿主Activity启动完毕后,调用此函数
onStart                    ()启动Fragment时,调用此函数。
onResume              ()Fragment恢复时,调用此函数。
onPause                 ()Fragment暂停时,调用此函数。
onStop                    ()Fragment停止时,调用此函数。
onDestroyView       ()销毁Fragment中的View控件时,调用此函数。
onDestroy              ()销毁Fragment时,调用此函数。
onDetach               ()Fragment从Activity脱离时,调用此函数


因为Fragment又称为碎片化组件,可以在一个Activity存在多个,所以使用Fragment可以完成复杂程序的编写。
二、ViewPager:是实现页面翻转的组件,里面可以放各种更小的组件,比如Fragment.因此可以在ViewPger里面放Fragment实现页面翻转;
三、ListView:可以列表化的组件;每一个ListView都是一个列表;把ListView放入Fragment可以实现简单的页面信息;
下面看一个简单实例:
代码部分:
1.自定义ViewPager适配器继承FragmentPagerAdapter;

<span style="font-size:18px;">import.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentPagerAdapter;import java.util.List;public class MyFragmentViewpagerAdapter extends FragmentPagerAdapter {    private  List<Fragment>list;    private  List<String> titles;    public MyFragmentViewpagerAdapter(FragmentManager fm,                                      List<Fragment>list,List<String> titles) {        super(fm);        this.list = list;        this.titles = titles;    }    @Override    public Fragment getItem(int position) {        return list.get(position);    }    @Override    public int getCount() {        return list.size();    }    @Override    public CharSequence getPageTitle(int position) {        return titles.get(position);    }}</span>
2.在主布局文件中,添加v4工具包中的ViewPager和第三方插件PagerSlidingTabStrip,以实现导航菜单和页面的跳转,并为此ViewPager添加适配器;
<span style="font-size:18px;">import android.os.Bundle;import android.support.v4.app.Fragment;import android.support.v4.view.ViewPager;import android.support.v7.app.AppCompatActivity;import com.astuetz.PagerSlidingTabStrip;import com.example.administrator.newstop.adapter.MyFragmentViewpagerAdapter;import com.example.administrator.newstop.fragment.PagerFragment;import java.util.ArrayList;import java.util.List;public class FragmentPagerActivity extends AppCompatActivity {    private ViewPager vp;    private PagerSlidingTabStrip pst;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_fragment_pager);        vp = (ViewPager) findViewById(R.id.vp);        pst = (PagerSlidingTabStrip) findViewById(R.id.pst);        List<Fragment> list = new ArrayList<>();        List<String> list1 = new ArrayList<>();        list1.add("推荐");        list1.add("热点");        list1.add("烟台");        list1.add("财经");        list1.add("体育");        for (int i =1;i<=5;i++){            Fragment fragment = new PagerFragment();            Bundle bundle = new Bundle();            bundle.putInt("key",i);            fragment.setArguments(bundle);            list.add(fragment);        }        vp.setAdapter(new MyFragmentViewpagerAdapter                (getSupportFragmentManager(),list,list1));        pst.setIndicatorColor(getResources().getColor(R.color.colorPrimary));        //更改指示器高度        pst.setIndicatorHeight(4);        //更改字体颜色        pst.setTextColor(getResources().getColor(R.color.colorAccent));        //指示器下面那条线的颜色,容易覆盖指示器//        pst.setUnderlineColor(getResources().getColor(R.color.colorAccent));        //均等分割标题栏,不然的话:如果有两个,它们会挤在头部,后面没东西很难看。        pst.setShouldExpand(true);        //标题各项分割线的颜色和分割线距离上下的长度        pst.setDividerPadding(20);        pst.setDividerColor(getResources().getColor(R.color.colorPrimary));        pst.setViewPager(vp);    }}</span>
3.新建一个碎片组件fragment,在它的布局上添加ListView组件。并为它添加一个ListView适配器;
<span style="font-size:18px;">import android.content.Intent;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.AdapterView;import android.widget.ListView;</span><span style="font-size: 13.5pt;"></span><span style="font-size:18px;">import com.example.administrator.newstop.IntentActivity;import com.example.administrator.newstop.R;import com.example.administrator.newstop.adapter.ListViewFragmentAdapter;import com.example.administrator.newstop.entity.News1;import java.util.ArrayList;import java.util.List;/** * A simple {@link Fragment} subclass. */public class PagerFragment extends Fragment {    public PagerFragment() {        // Required empty public constructor    }    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,                             Bundle savedInstanceState) {        // Inflate the layout for this fragment        return inflater.inflate(R.layout.fragment_pager, container, false);    }    @Override    public void onActivityCreated(@Nullable Bundle savedInstanceState) {        super.onActivityCreated(savedInstanceState);        final List<News1> list = new ArrayList<>();        ListView lv = (ListView) getView().findViewById(R.id.lv);        Bundle bundle = getArguments();        ListViewFragmentAdapter la =                new ListViewFragmentAdapter(getActivity(),list);        lv.setAdapter(la);        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {                Intent intent = new Intent(getActivity(), IntentActivity.class);                startActivity(intent);            }        });        if (bundle != null) {            int arg = bundle.getInt("key");            switch (arg) {                /*                * (int imgRes, String title, String content, String from) */            case 1:for(int i =1;i<=15;i++){                list.add(new News1(R.mipmap.ic_launcher,"标题"+i,"这是一门神奇的语言","11小时前"));            }              la.notifyDataSetChanged();                break;            case 2:for(int i =1;i<=15;i++){                list.add(new News1(R.mipmap.ic_launcher,"标题"+i,"这是一门神奇的语言","13小时前"));            }              la.notifyDataSetChanged();                break;            case 3:for(int i =1;i<=15;i++){                list.add(new News1(R.mipmap.ic_launcher,"标题"+i,"这是一门神奇的语言","12小时前"));            }              la.notifyDataSetChanged();                break;            case 4:for(int i =1;i<=15;i++){                list.add(new News1(R.mipmap.ic_launcher,"标题"+i,"这是一门神奇的语言","13小时前"));            }              la.notifyDataSetChanged();                break;            case 5:for(int i =1;i<=15;i++){                list.add(new News1(R.mipmap.ic_launcher,"标题"+i,"这是一门神奇的语言","14小时前"));            }              la.notifyDataSetChanged();                break;            }        }    }}</span>
4.listView的适配器,对具体数据的处理(这里是自定义的一个新闻类),
<span style="font-size:18px;">package com.example.administrator.newstop.adapter;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.TextView;import com.example.administrator.newstop.R;import com.example.administrator.newstop.entity.News1;import java.util.List;public class ListViewFragmentAdapter extends BaseAdapter {    private List<News1> list;    private Context context;    public ListViewFragmentAdapter(Context context, List<News1> list) {        this.context = context;        this.list = list;    }    @Override    public int getCount() {        return list.size();    }    @Override    public Object getItem(int i) {        return list.get(i);    }    @Override    public long getItemId(int i) {        return 0;    }    @Override    public View getView(int i, View view, ViewGroup viewGroup) {        ViewHolder vh;        if(view == null){            vh = new ViewHolder();            view = LayoutInflater.from(context)                    .inflate(R.layout.list_layout,null);            vh.title = (TextView) view.findViewById(R.id.title);            vh.img = (ImageView) view.findViewById(R.id.iv);            vh.content = (TextView) view.findViewById(R.id.content);            vh.from = (TextView) view.findViewById(R.id.from);            view.setTag(vh);        } else {            vh = (ViewHolder) view.getTag();        }           News1 news1 = list.get(i);           vh.title.setText(news1.getTitle());           vh.from.setText(news1.getFrom());           vh.img.setImageResource(news1.getImgRes());           vh.content.setText(news1.getContent());        return view;    }    private class ViewHolder{         private  TextView title,from,content;         private  ImageView img;    }}</span>
截图:

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