Activity ViewPager Fragment错误笔记与简单demo

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一直对Activity viewpager Fragment之间的应用有些问题，今天整理个小而简陋的demo记录下，希望看到的人有所收获，也很希望懂得的朋友给予些好的指点，优化，先谢过！

1.调用FragmentManager fm=getSupportFragmentManager();报错

原因：getSupportFragmentManager（）是android.support.v4.app.FragmentActivity的

解决方案：

Activity继承android.support.v4.app.FragmentActivity即可

2.在Activity里有个按钮入点击后Fragment的数据进行排序：之前我走入了歧途在fragment中通过getActivity().findViewById(R.id.btpaixu)，然后设置监听，进行相关排序操作

结果当前fragment不起作用，最后一个fragment排了序，

原因不详

解决方案：

在activity中获得按钮控件设置点击监听，在监听方法中获得当前fragment，调用fragment的数据排序方法

代码见下：

3.activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/bt_more" >

        </android.support.v4.view.ViewPager>

    <Button
        android:id="@+id/bt_more"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="加载更多" />

    <Button
        android:id="@+id/bt_paixu"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_marginRight="16dp"
        android:text="排序" />

</RelativeLayout>

4.MainActivity.java

package com.example.zfragment;

import java.util.ArrayList;

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.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends FragmentActivity {

   ViewPager pager;
   ArrayList<ItemFragment> fragments;
   private Button btMore;
   protected int currentpostion;
   private Button btPaiXu;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       pager=(ViewPager)findViewById(R.id.pager);
       initViews();
       FragmentManager fm=getSupportFragmentManager();
       MyViewAdapter adapter=new MyViewAdapter(fm);
       pager.setOffscreenPageLimit(fragments.size());
       pager.setAdapter(adapter);
       pager.setOnPageChangeListener(new OnPageChangeListener() {

           @Override
           public void onPageSelected(int arg0) {
               currentpostion=arg0;// TODO 保存当前索引
               if(fragments.get(arg0)==null){
                   ItemFragment f=new ItemFragment();
                   Bundle args = new Bundle();
                   args.putInt("type",arg0);
                   f.setArguments(args);
                   fragments.add(f);
               }else{
                   ItemFragment f=fragments.get(arg0);
                   // TODO 如果是切换再去加载数据可以在此处调用fragment的加载数据的方法
                   //f.loadData();
               }
           }

           @Override
           public void onPageScrolled(int arg0, float arg1, int arg2) {


           }

           @Override
           public void onPageScrollStateChanged(int arg0) {

           }
       });
       // TODO 设置MainActivity监听，fragment进行相关的操作
       setMoreListener();
   }

   private void setMoreListener() {
       btMore= (Button) findViewById(R.id.bt_more);
       btMore.setOnClickListener(new OnClickListener() {

           @Override
           public void onClick(View arg0) {
               Toast.makeText(MainActivity.this, "过几秒向上滑动可以看到数据", 5000).show();
               fragments.get(currentpostion).loadMore();//加载更多的方法
           }
       });
       btPaiXu= (Button) findViewById(R.id.bt_paixu);
       btPaiXu.setOnClickListener(new OnClickListener() {

           @Override
           public void onClick(View arg0) {

               fragments.get(currentpostion).paixu();//调用fragment的排序方法
           }
       });
   }

   private void initViews() {
       fragments=new ArrayList<ItemFragment>();
       for (int i = 0; i < 6; i++) {
           ItemFragment f=new ItemFragment();
           Bundle args = new Bundle();
           args.putInt("type",i);
           f.setArguments(args);
           fragments.add(f);
       }
   }

   @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;
   }

   class MyViewAdapter extends FragmentPagerAdapter{

       public MyViewAdapter(FragmentManager fm) {
           super(fm);
       }

       @Override
       public Fragment getItem(int arg0) {
           return fragments.get(arg0);
       }

       @Override
       public int getCount() {
           return fragments.size();
       }

   }

}

5.item_fragment.xml

package com.example.zfragment;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class ItemFragment extends Fragment{
   private View view;
   private ListView listView;
   private MyAdapter adapter;
   private int type;
   protected ArrayList<String> datas;
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);

   }

   @Override
   public void onPause() {
       super.onPause();
   }
   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container,
           Bundle savedInstanceState) {
       view=inflater.inflate(R.layout.item_fragment, container,false);
       listView=(ListView) view.findViewById(R.id.listView1);
       this.type=getArguments().getInt("type");
       return view;
   }


   protected void loadMore() {
       final Handler h=new Handler(){
           @Override
           public void handleMessage(Message msg) {
               super.handleMessage(msg);
               switch (msg.what) {
               case 2:
                   ArrayList<String> tmp=(ArrayList<String>) msg.obj;
                   datas.addAll(datas.size(),tmp);
                   adapter.notifyDataSetChanged(datas);
                   break;

               default:
                   break;
               }
           }
       };

       new Thread(){
           public void run() {
               ArrayList<String> datas=new ArrayList<String>();
               for (int i = 0; i < 20; i++) {
                   datas.add("更多"+"--"+type+"--"+i);
               }
               try {
                   sleep(3000);
                   Message msg=Message.obtain(h, 2);
                   msg.obj=datas;
                   msg.sendToTarget();
               } catch (InterruptedException e) {
                   e.printStackTrace();
               }

           };
       }.start();

   }

   @Override
   public void onActivityCreated(Bundle savedInstanceState) {
       super.onActivityCreated(savedInstanceState);

       final Handler handle=new Handler(){
           @Override
           public void handleMessage(Message msg) {
               super.handleMessage(msg);
               if(msg.what==1){
                   datas=(ArrayList<String>) msg.obj;
                   adapter=new MyAdapter(datas);
                   listView.setAdapter(adapter);

               }
           }
       };

       new Thread(){
           public void run() {
               ArrayList<String> datas=new ArrayList<String>();
               for (int i = 0; i <50; i++) {
                   datas.add("item"+"--"+type+"--"+i);
               }
               try {
                   sleep(3000);
                   Message msg=Message.obtain(handle, 1);
                   msg.obj=datas;
                   msg.sendToTarget();
               } catch (InterruptedException e) {
                   e.printStackTrace();
               }

           };
       }.start();

   }

   class MyAdapter extends BaseAdapter{

       ArrayList<String>datas;
       public MyAdapter(ArrayList<String>datas){
           this.datas=datas;
       }
       public void notifyDataSetChanged(ArrayList<String> datas2) {
           this.datas=datas2;
           notifyDataSetChanged();

       }
       @Override
       public int getCount() {
           // TODO Auto-generated method stub
           return datas.size();
       }

       @Override
       public Object getItem(int arg0) {
           // TODO Auto-generated method stub
           return datas.get(arg0);
       }

       @Override
       public long getItemId(int arg0) {
           // TODO Auto-generated method stub
           return arg0;
       }

       @Override
       public View getView(int arg0, View arg1, ViewGroup arg2) {
           TextView tv=new TextView(getActivity());
           tv.setText(datas.get(arg0));
           return tv;
       }

   }

   public void paixu() {
       Collections.sort(datas,new Comparator<String>() {

           @Override
           public int compare(String arg0, String arg1) {
               return arg0.length()-arg1.length();
           }
       });
       adapter.notifyDataSetChanged(datas);
   }
}

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