FragmentPagerAdapter——滑动添加Fragment

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FragmentPagerAdapter是PagerAdapter中的其中一种实现。它将每一个页面表示为一个 Fragment，并且每一个Fragment都将会保存到fragment manager当中。当页面数量比较大的时候，建议使用FragmentStatePagerAdapter。

当使用FragmentPagerAdapter的时候，ViewPager一定要使用正确的ID set。

FragmentPagerAdapter的子类只要实现 getItem(int) 和 getCount()方法
在XML中定义布局，在底部定义一个RadioGroup，添加三个RadioButton。添加一个ViewPager布局。

<LinearLayout 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"    android:orientation="vertical"    tools:context=".MainActivity">    <LinearLayout        android:id="@+id/linearlayout"        android:layout_width="match_parent"        android:layout_height="60dp"        android:orientation="horizontal"        android:layout_alignParentTop="true"        android:background="#17B4EB">    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="30dp"        android:background="#cfcfcf"        android:layout_marginTop="15dp">        <EditText            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_marginLeft="10dp"            android:layout_marginRight="10dp"            android:background="@mipmap/text"            android:gravity="center"            android:hint="搜索"/>    </LinearLayout>    <android.support.v4.view.ViewPager        class="com.example.administrator.myfragment.fragment.MyFirstFragment"        android:id="@+id/fragment_viewpager"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_weight="1"></android.support.v4.view.ViewPager>    <RadioGroup        android:id="@+id/fragment_radiogroup"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:gravity="center"        android:orientation="horizontal">        <RadioButton            android:id="@+id/button1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:drawableTop="@drawable/contact"            style="@style/fragment"/>        <RadioButton            android:id="@+id/button2"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:drawableTop="@drawable/conversation"            style="@style/fragment"            />        <RadioButton            android:id="@+id/button3"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:drawableTop="@drawable/plugin"            style="@style/fragment"/>    </RadioGroup></LinearLayout>

定义一个Adapter类，继承自FragmentPagerAdapter，重写两个方法

package com.example.administrator.myfragment.adapter;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentPagerAdapter;import java.util.List;/** * Created by Administrator on 2015/9/7. */public class MyFragmentAdapter extends FragmentPagerAdapter {    private List<Fragment>mFragments;    public MyFragmentAdapter(FragmentManager fm,List<Fragment> mFragments) {        super(fm);        this.mFragments=mFragments;    }    @Override    public Fragment getItem(int position) {        return mFragments.get(position);    }    @Override    public int getCount() {        return mFragments.size();    }}

在MainActivity中完善代码，主要是将适配器添加到ViewPager中

package com.example.administrator.myfragment;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentActivity;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentTransaction;import android.support.v4.view.ViewPager;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.ViewGroup;import android.widget.Button;import android.widget.FrameLayout;import android.widget.LinearLayout;import android.widget.RadioGroup;import com.example.administrator.myfragment.adapter.MyFragmentAdapter;import com.example.administrator.myfragment.fragment.MyFirstFragment;import com.example.administrator.myfragment.fragment.MySecondFragment;import com.example.administrator.myfragment.fragment.MyThirdFragment;import java.util.ArrayList;import java.util.List;public class MainActivity extends FragmentActivity {    private MyFirstFragment mMyFirstFragment;    private MySecondFragment mMySecondFragment;    private MyThirdFragment mMyThirdFragment;    private FragmentManager mFragmentManager;    private FragmentTransaction mFragmentTransaction;    private List<Fragment>mFragments;    private ViewPager mViewPager;    private RadioGroup mRadioGroup;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mViewPager= (ViewPager) findViewById(R.id.fragment_viewpager);        mRadioGroup= (RadioGroup) findViewById(R.id.fragment_radiogroup);        mFragmentManager=getSupportFragmentManager();        mFragments=new ArrayList<>();        mMyFirstFragment=new MyFirstFragment();        mMySecondFragment=new MySecondFragment();        mMyThirdFragment =new MyThirdFragment();        mFragments.add(mMyFirstFragment);        mFragments.add(mMySecondFragment);        mFragments.add(mMyThirdFragment);        mFragmentTransaction=mFragmentManager.beginTransaction();        MyFragmentAdapter mAdapter=new MyFragmentAdapter(mFragmentManager,mFragments);        mViewPager.setAdapter(mAdapter);        mRadioGroup.check(R.id.button1);        mRadioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {            @Override            public void onCheckedChanged(RadioGroup group, int checkedId) {                switch (checkedId){                    case R.id.button1:                       mViewPager.setCurrentItem(0);                        break;                    case R.id.button2:                        mViewPager.setCurrentItem(1);                        break;                    case R.id.button3:                        mViewPager.setCurrentItem(2);                        break;                    default:                        break;                }            }        });       mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {           @Override           public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {           }           @Override           public void onPageSelected(int position) {               switch (position){                   case 0:                       mRadioGroup.check(R.id.button1);                       break;                   case 1:                       mRadioGroup.check(R.id.button2);                       break;                   case 2:                       mRadioGroup.check(R.id.button3);                       break;                   default:                       break;               }           }           @Override           public void onPageScrollStateChanged(int state) {           }       });    }}

这里添加点击事件主要是在点击下边的Button和滑动屏幕的时候保持一致性。

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