如何知道哪个片段是可见的？
如何知道哪个片段是可见的？
提问于 2018-06-05 01:52:22
我有一个带有片段幻灯片的浏览页，我需要知道哪一个在屏幕上，以便将一些结果返回到正确的字段。如何知道屏幕上有什么？
代码如下：
//Activity
public class ActivityAtendimentoTab extends AppCompatActivity{
private ResultFragmentsCondutas resultFragmentsCondutas;
//método para que possa ser passado os valores falados para os fragments.
public interface ResultFragmentsCondutas {
void showCondutaResults(ArrayList<String> results);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_atendimento_tab);
......
vpPager = (ViewPager) findViewById(R.id.vpPager);
adapterViewPager = new MyPagerAdapter(getSupportFragmentManager());
vpPager.setAdapter(adapterViewPager);
vpPager.addOnPageChangeListener(viewPagerPageChangeListener);
..
}
}下面是viewpager，它是一个内部类：
//ViewPager inner class ActivityAtendimentoTab
public static class MyPagerAdapter extends FragmentPagerAdapter {
private static int NUM_ITEMS = 2;
public MyPagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
// Returns total number of pages
@Override
public int getCount() {
return NUM_ITEMS;
}
// Returns the fragment to display for that page
@Override
public Fragment getItem(int position) {
switch (position) {
case 0: // Fragment # 0 - This will show FirstFragment
return new FragmentAvaliacao();
case 1: // Fragment # 0 - This will show FirstFragment different title
return new FragmentReceita()
default:
return null;
}
}
// Returns the page title for the top indicator
@Override
public CharSequence getPageTitle(int position) {
return "Page " + position;
}
}我需要知道屏幕上显示的是哪一个，以便从界面返回一些结果。遵循以下代码：
@Override
public void onResults(Bundle results) {
//inicializando as variáveis de fragments
av = (FragmentAvaliacao) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_avaliacao));//NULL
//pegando a lista de comandos
ArrayList<String> matches = results
.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
//Verifica qual fragment está chamando a interface
//e passa o valor da string para que seja implementada nos respectivos campos.
try {
if (vpPager.getCurrentItem() == 0) {//TRUE
resultFragmentsCondutas = av;
resultFragmentsCondutas.showCondutaResults(matches);
}如何初始化av (示例)，始终为空。
回答 1
Stack Overflow用户
回答已采纳
发布于 2018-06-05 01:59:47
如果我没理解错的话，你需要知道当你滑动它时，哪个片段是可见的。
first选项：
viewPager.addOnPageChangeListener(new OnPageChangeListener() {
public void onPageScrollStateChanged(int state) {
}
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
public void onPageSelected(int position) {
// Check if this is the page you want by position
if{position==0){
//is FragmentAvaliacao() do something
} else{
//is FragmentReceita() do something
}
}
});在本例中，int onPageSelected(int位置)检查它是0表示"FragmentAvaliacao()“，还是1表示FragmentReceita()
第二个选项
@Override
public void onResults(Bundle results) {
Fragment page = getSupportFragmentManager().findFragmentByTag("android:switcher:" + R.id.of_your_viewpager + ":" + viewPager.getCurrentItem());
if (ViewPager.getCurrentItem() == 0 && page != null) {
((FragmentAvaliacao)page).showCondutaResults(matches);
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50686203
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