Androidbby

 private static final int QUANTITY = 4;    private FrameLayout flMain;    private List<Fragment> fragments;    private RadioGroup rgNavigation;    private int currentIndex = 0;  //导航切换    private void radioGroupManage() {        fragments = new ArrayList<>();        final RadioButton[] buttons=new RadioButton[QUANTITY];        assert rgNavigation!=null;        for(int i=0;i<rgNavigation.getChildCount();i++){            //获取第i个位置上的子控件            buttons[i] = (RadioButton) rgNavigation.getChildAt(i);            //往集合中添加Fragment对象            fragments.add(FragmentFactory.createFragment(i));        }        //默认加载第一个Fragment对象        getSupportFragmentManager().beginTransaction().add(R.id.fl_main,fragments.get(0)).commit();        //处理单机事件        rgNavigation.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {            @Override            public void onCheckedChanged(RadioGroup group, int checkedId) {                for(int i=0;i<rgNavigation.getChildCount();i++){                    if(buttons[i].getId()==checkedId){                        switchFragment(i);                    }                }            }        });    }    //切换Fragment的方法    private void switchFragment(int targetIndex) {        //目标的Fragment        Fragment targetFragment = fragments.get(targetIndex);        //当前的Fragment        Fragment currentFragment = fragments.get(currentIndex);        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();        if(targetFragment.isAdded()){            //目标Fragment已经被添加了...则隐藏当前正在展示的Fragment,显示目标Fragment            fragmentTransaction.hide(currentFragment).show(targetFragment);        }else {            //没有被添加...则隐藏当前的Fragment,添加目标Fragment            fragmentTransaction.hide(currentFragment).add(R.id.fl_main,targetFragment);        }        fragmentTransaction.commit();        //改变当前索引值        currentIndex=targetIndex;    }

public class FragmentFactory  {    private static final int FRAGMENT_INDEX = 0;    private static final int FRAGMENT_CATEGORY = 1;    private static final int FRAGMENT_FIND = 2;    private static final int FRAGMENT_MINE = 3;    private static SparseArray<Fragment> fragments = new SparseArray<>();    public static Fragment createFragment(int index){        Fragment fragment = fragments.get(index);        if(fragment == null){            switch (index){                case FRAGMENT_INDEX:                    fragment = new IndexFragment();                    break;                case FRAGMENT_CATEGORY:                    fragment =  new CategoryFragment();                   break;                case FRAGMENT_FIND:                    fragment =  new FindFragment();                   break;                case FRAGMENT_MINE:                    fragment =  new MineFragment();                   break;            }            fragments.put(index,fragment);        }        return fragment;    }}

<style name="rb_style">    <item name="android:gravity">center</item>    <item name="android:layout_width">0dp</item>    <item name="android:layout_height">wrap_content</item>    <item name="android:layout_weight">1</item>    <item name="android:button">@null</item></style>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_main"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="bby.com.projecttemplate.ui.MainActivity">    <FrameLayout        android:id="@+id/fl_main"        android:layout_above="@+id/rg_navigation_main"        android:layout_width="match_parent"        android:layout_height="match_parent" />    <!--<TextView-->        <!--android:layout_width="match_parent"-->        <!--android:layout_height="1dp"-->        <!--android:background="#c4c3c3"/>-->    <RadioGroup        android:id="@+id/rg_navigation_main"        android:layout_alignParentBottom="true"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal"        android:padding="2dp"        android:background="#fff">        <RadioButton            android:id="@+id/rb_index_navigation_main"            style="@style/rb_style"            android:text="首页"            android:checked="true"            android:drawableTop="@drawable/selector_navigation_index"/>        <RadioButton            android:id="@+id/rb_category_navigation_main"            style="@style/rb_style"            android:text="分类"            android:drawableTop="@drawable/selector_navigation_category"/>        <RadioButton            android:id="@+id/rb_find_navigation_main"            style="@style/rb_style"            android:text="发现"            android:drawableTop="@drawable/selector_navigation_find"/>        <RadioButton            android:id="@+id/rb_mine_navigation_main"            style="@style/rb_style"            android:text="我"            android:drawableTop="@drawable/selector_navigation_mine"/>    </RadioGroup></RelativeLayout>