对BottomTagFragment的理解

代码比较简单而且已经有很多的注释

package com.jay.fragmentdemo4;

import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

/**
 * Created by Coder-pig on 2015/8/28 0028.
 */
public class MainActivity extends AppCompatActivity implements RadioGroup.OnCheckedChangeListener,
        ViewPager.OnPageChangeListener {

    //UI Objects
    private TextView txt_topbar;

    private RadioGroup rg_tab_bar;
    private RadioButton rb_channel;
    private RadioButton rb_message;
    private RadioButton rb_better;
    private RadioButton rb_setting;

    private ViewPager vpager;

    private MyFragmentPagerAdapter mAdapter;

    //几个代表页面的常量
    public static final int PAGE_ONE = 0;
    public static final int PAGE_TWO = 1;
    public static final int PAGE_THREE = 2;
    public static final int PAGE_FOUR = 3;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //getSupportFragmentManager()返回一个fragmentManager的对象
        mAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager());
        bindViews();
        rb_channel.setChecked(true);
    }

    private void bindViews() {
        //一个在顶部的提醒文本
        txt_topbar = (TextView) findViewById(R.id.txt_topbar);

        rg_tab_bar = (RadioGroup) findViewById(R.id.rg_tab_bar);
        rb_channel = (RadioButton) findViewById(R.id.rb_channel);
        rb_message = (RadioButton) findViewById(R.id.rb_message);
        rb_better = (RadioButton) findViewById(R.id.rb_better);
        rb_setting = (RadioButton) findViewById(R.id.rb_setting);
        //RadioGroup监听
        rg_tab_bar.setOnCheckedChangeListener(this);

        //这里是滑动页面的布局
        vpager = (ViewPager) findViewById(R.id.vpager);
        vpager.setAdapter(mAdapter);
        vpager.setCurrentItem(PAGE_ONE);
        //ViewPager监听
        vpager.addOnPageChangeListener(this);
    }

    //这个是按下RadioButton的响应的事件
    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        switch (checkedId) {
            case R.id.rb_channel:
                vpager.setCurrentItem(PAGE_ONE);
                break;
            case R.id.rb_message:
                vpager.setCurrentItem(PAGE_TWO);
                break;
            case R.id.rb_better:
                vpager.setCurrentItem(PAGE_THREE);
                break;
            case R.id.rb_setting:
                vpager.setCurrentItem(PAGE_FOUR);
                break;
        }
    }


    //重写ViewPager页面切换的处理方法
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    }

    @Override
    public void onPageSelected(int position) {
    }
//滑动的方法
    @Override
    public void onPageScrollStateChanged(int state) {
        //state的状态有三个，0表示什么都没做，1正在滑动，2滑动完毕
        if (state == 2) {
            switch (vpager.getCurrentItem()) {
                case PAGE_ONE:
                    rb_channel.setChecked(true);
                    break;
                case PAGE_TWO:
                    rb_message.setChecked(true);
                    break;
                case PAGE_THREE:
                    rb_better.setChecked(true);
                    break;
                case PAGE_FOUR:
                    rb_setting.setChecked(true);
                    break;
            }
        }
    }
}

package com.jay.fragmentdemo4;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.view.ViewGroup;

/**
 * Created by Jay on 2015/8/31 0031.
 */
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {

    private final int PAGER_COUNT = 4;
    private MyFragment1 myFragment1 = null;
    private MyFragment2 myFragment2 = null;
    private MyFragment3 myFragment3 = null;
    private MyFragment4 myFragment4 = null;


    public MyFragmentPagerAdapter(FragmentManager fm) {
        super(fm);
        myFragment1 = new MyFragment1();
        myFragment2 = new MyFragment2();
        myFragment3 = new MyFragment3();
        myFragment4 = new MyFragment4();
    }


    @Override
    public int getCount() {
        return PAGER_COUNT;
    }

    @Override
    public Object instantiateItem(ViewGroup vg, int position) {
        return super.instantiateItem(vg, position);
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        System.out.println("position Destory" + position);
        super.destroyItem(container, position, object);
    }

    //切换到哪个fragment就new 相应的Fragment，显示一个fragment
    @Override
    public Fragment getItem(int position) {
        Fragment fragment = null;
        switch (position) {
            //fragment与页面绑定
            case MainActivity.PAGE_ONE:
                fragment = myFragment1;
                break;
            case MainActivity.PAGE_TWO:
                fragment = myFragment2;
                break;
            case MainActivity.PAGE_THREE:
                fragment = myFragment3;
                break;
            case MainActivity.PAGE_FOUR:
                fragment = myFragment4;
                break;
        }
        return fragment;
    }


}

已经发现一个问题就是 隔着切换底部标签的时候（例如先点击提醒，然后点击我的）在第一个fragment调到第三个fragment的时候会出现 第二个fragment.目前我还没有想出解决办法，如果小伙伴知道，欢迎留言，谢谢。

现在知道是什么原因了，并找到解决的办法 

demo下载地址  http://pan.baidu.com/s/1o8GN5N0

这个代码存在的一个bug ,当频繁的左右滑动和点击底部标签的时候会卡死

解决办法是：

参考链接：

http://ju.outofmemory.cn/entry/138935