项目首页使用RadioGroup+RadioButton+Fragment实现页面切换,出现了一个问题fragment会出现重叠问题,就是一个fragment显示了两层,
并不是必现问题。
经过排查发现是项目主页面Activity被销毁重建了,但是之前的fragment对象没有被回收导致。
在旋转屏幕后或者页面调到后台一段时间在打开,就会出现Fragment重叠显示,显示了两个相同fragment的效果。
第一步,在添加fragment的时候添加key。
第二步,再onCreate里判断savedInstanceState是否为空,若不为空说 明是重建的activity,用key将fragment对象取出来即可。
下面我们来看一下具体代码
private FragmentManager fManager;
private FragmentTransaction transaction;
private List<Fragment> fragmentList = new ArrayList<>();
private FragmentOne fragmentOne;
private FragmentTwo fragmentTwo;
private FragmentFour fragmentFour;
private FragmentFive fragmentFive;
private static final String FRAGMENT_ONE_KEY = "FragmentOne";
private static final String FRAGMENT_TWO_KEY = "FragmentTwo";
private static final String FRAGMENT_FOUR_KEY = "FragmentFour";
private static final String FRAGMENT_FIVE_KEY = "FragmentFive";
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fManager = getSupportFragmentManager();
//如果activity销毁后重建,在这里拿出之前的Fragment对象。
if (savedInstanceState != null) {
fragmentOne = (FragmentOne) fManager.findFragmentByTag(FRAGMENT_ONE_KEY);
fragmentTwo = (FragmentTwo) fManager.findFragmentByTag(FRAGMENT_TWO_KEY);
fragmentFour = (FragmentFour) fManager.findFragmentByTag(FRAGMENT_FOUR_KEY);
fragmentFive = (FragmentFive) fManager.findFragmentByTag(FRAGMENT_FIVE_KEY);
initFragment(fragmentOne);
initFragment(fragmentTwo);
initFragment(fragmentFour);
initFragment(fragmentFive);
}
initView();
}
private void initView() {
fragmentOne = (FragmentOne) fManager.findFragmentByTag(FRAGMENT_ONE_KEY);
if (fragmentOne == null) {
fragmentOne = new FragmentOne();
fragmentList.add(fragmentOne);
hideOthersFragment(fragmentOne, true, FRAGMENT_ONE_KEY);
} else {
hideOthersFragment(fragmentOne, false, FRAGMENT_ONE_KEY);
}
radioGroup.setOnCheckedChangeListener((group, checkedId) -> {
switch (checkedId) {
case R.id.radio1:
if (fragmentOne == null) {
fragmentOne = new FragmentOne();
fragmentList.add(fragmentOne);
hideOthersFragment(fragmentOne, true, FRAGMENT_ONE_KEY);
} else {
hideOthersFragment(fragmentOne, false, FRAGMENT_ONE_KEY);
}
break;
case R.id.radio2:
if (fragmentTwo == null) {
fragmentTwo = new FragmentTwo();
fragmentList.add(fragmentTwo);
hideOthersFragment(fragmentTwo, true, FRAGMENT_TWO_KEY);
} else {
hideOthersFragment(fragmentTwo, false, FRAGMENT_TWO_KEY);
}
break;
case R.id.radio4:
if (fragmentFour == null) {
fragmentFour = new FragmentFour();
fragmentList.add(fragmentFour);
hideOthersFragment(fragmentFour, true, FRAGMENT_FOUR_KEY);
} else {
hideOthersFragment(fragmentFour, false, FRAGMENT_FOUR_KEY);
}
break;
case R.id.radio5:
if (fragmentFive == null) {
fragmentFive = new FragmentFive();
fragmentList.add(fragmentFive);
hideOthersFragment(fragmentFive, true, FRAGMENT_FIVE_KEY);
} else {
hideOthersFragment(fragmentFive, false, FRAGMENT_FIVE_KEY);
}
break;
}
});
}
下面是两个方法
//将fragment对象添加进fragmentList
public void initFragment(Fragment fragment) {
if (fragment != null) {
fragmentList.add(fragment);
}
}
}
//加载fragment
public void hideOthersFragment(Fragment showFragment, boolean isAdd, String key) {
transaction = fManager.beginTransaction();
if (isAdd) {
//这里别忘了添加key
transaction.add(R.id.Frame_ID, showFragment, key);
}
if (ObjectUtils.isNotEmpty(fragmentList)) {
for (Fragment fragment : fragmentList) {
if (showFragment.equals(fragment)) {
transaction.show(fragment);
} else {
transaction.hide(fragment);
}
}
transaction.commit();
}
}