Android底部菜单栏（RadioGroup+Fragment）美化

public class MainActivity extends AppCompatActivity {
 
 private FrameLayout frameLayout;
 private RadioGroup radioGroup;
 private Fragment[] mFragments;
 private int mIndex;
 
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  initFragment();
  setRadioGroupListener();
 
 
 }
 
 private void initFragment() {
  radioGroup = (RadioGroup) findViewById(R.id.radioGroup);
  frameLayout = (FrameLayout) findViewById(R.id.fl_content);
  HomeFragment homeFragment = new HomeFragment();
  ShopFragment shopFragment = new ShopFragment();
  LiveFragment liveFragment = new LiveFragment();
  ShoppingCarFragment shoppingCarFragment = new ShoppingCarFragment();
  MineFragment mineFragment = new MineFragment();
  //添加到数组
  mFragments = new Fragment[]{homeFragment, shopFragment, liveFragment, shoppingCarFragment, mineFragment};
  //开启事务
  FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
  //添加首页
  ft.add(R.id.fl_content, homeFragment).commit();
  //默认设置为第0个
  setIndexSelected(0);
 }
 
 private void setIndexSelected(int index) {
  if (mIndex == index) {
   return;
  }
  FragmentManager fragmentManager = getSupportFragmentManager();
  FragmentTransaction ft = fragmentManager.beginTransaction();
  //隐藏
  ft.hide(mFragments[mIndex]);
  //判断是否添加
  if (!mFragments[index].isAdded()) {
   ft.add(R.id.fl_content, mFragments[index]).show(mFragments[index]);
  } else {
   ft.show(mFragments[index]);
  }
  ft.commit();
  //再次赋值
  mIndex = index;
 
 }
 
 private void setRadioGroupListener() {
  radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
   @Override
   public void onCheckedChanged(RadioGroup radioGroup, int i) {
    switch (i) {
     case R.id.rb_home:
      setIndexSelected(0);
      break;
     case R.id.rb_shop:
      setIndexSelected(1);
      break;
     case R.id.rb_live:
      setIndexSelected(2);
      break;
     case R.id.rb_shopping_car:
      setIndexSelected(3);
      break;
     case R.id.rb_mine:
      setIndexSelected(4);
      break;
     default:
      setIndexSelected(0);
      break;
    }
   }
  });
 }
 
 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
  if (keyCode == KeyEvent.KEYCODE_BACK) {
   //仅当activity为task根（即首个启动activity）时才生效,这个方法不会改变task中的activity状态，
   // 按下返回键的作用跟按下HOME效果一样；重新点击应用还是回到应用退出前的状态；
   moveTaskToBack(false);
   return true;
  }
  return super.onKeyDown(keyCode, event);
 }
}

public class HomeFragment extends BaseFragment {
 
 public HomeFragment() {
 }
 
 
 @Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
  View view=inflater.inflate(R.layout.fragment_home,container,false);
  return view;
 }
 
 
}

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