我在我的应用程序中使用视图分页器，该视图分页器包含三个布局，我可以在它们之间很好地滑动，它显示了不同的布局文件，但是当我尝试在此布局上使用Java订单时，我发现没有任何变化例如，布局我试图更改textView的文本，但发现它没有改变
这是主要的活动代码：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
ActionBar actionBar = getSupportActionBar();
assert actionBar != null;
actionBar.setDisplayShowTitleEnabled(false);
mAuth = FirebaseAuth.getInstance();
database = FirebaseDatabase.getInstance();
myRef = database.getReference("posts");
mViewPager = findViewById(R.id.viewpager);
adapter = new SamplePagerAdapter(this);
tabLayout = findViewById(R.id.tablayout);
mViewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(mViewPager);
mViewPager.setCurrentItem(1);
TextView tabOne = (TextView) LayoutInflater.from(this).inflate(R.layout.custom_tab, null);
tabOne.setText("تعلم");
tabOne.setCompoundDrawablesWithIntrinsicBounds(0, R.drawable.learn, 0, 0);
tabLayout.getTabAt(0).setCustomView(tabOne);
TextView tabTwo = (TextView) LayoutInflater.from(this).inflate(R.layout.custom_tab, null);
tabTwo.setText("الصفحة الرئيسية");
tabTwo.setCompoundDrawablesWithIntrinsicBounds(0, R.drawable.home, 0, 0);
tabLayout.getTabAt(1).setCustomView(tabTwo);
TextView tabThree = (TextView) LayoutInflater.from(this).inflate(R.layout.custom_tab, null);
tabThree.setText("التحديات");
tabThree.setCompoundDrawablesWithIntrinsicBounds(0, R.drawable.challenges, 0, 0);
tabLayout.getTabAt(2).setCustomView(tabThree);
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
tabPosition = tab.getPosition();
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main_menu, menu);
return true;
}
这是片段的Java代码：
// TODO: Rename and change types and number of parameters
public static HomeFragment newInstance(String param1, String param2) {
HomeFragment fragment = new HomeFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
database = FirebaseDatabase.getInstance();
myRef = database.getReference("posts");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View myView = inflater.inflate(R.layout.fragment_home, container, false);
etAddPost = myView.findViewById(R.id.etAddPost);
TextView tv = myView.findViewById(R.id.testText);
tv.setText("new text");
addPostBtn(myView);
return myView;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
这是视图寻呼机适配器代码：
public class SamplePagerAdapter extends PagerAdapter {
Context context;
public SamplePagerAdapter(Context context) {
this.context = context;
}
/**
* @return the number of pages to display
*/
@Override
public int getCount() {
return 3;
}
/**
* @return true if the value returned from {@link #instantiateItem(ViewGroup, int)} is the
*/
@Override
public boolean isViewFromObject(View view, Object o) {
return o == view;
}
// BEGIN_INCLUDE (pageradapter_getpagetitle)
/**
* Return the title of the item at {@code position}. This is important as what this method
* <p>
* Here we construct one using the position value, but for real application the title should
* refer to the item's contents.
*/
@Override
public CharSequence getPageTitle(int position) {
String title = "";
switch (position) {
case 0:
title = "تعلم";
break;
case 1:
title = "الصفحة الرئيسية";
break;
case 2:
title = "التحديات";
break;
}
return title;
}
// END_INCLUDE (pageradapter_getpagetitle)
/**
* Instantiate the {@link View} which should be displayed at {@code position}. Here we
* inflate a layout from the apps resources and then change the text view to signify the position.
*/
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
// Inflate a new layout from our resources
LayoutInflater li = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
assert li != null;
View view = null;
switch (position) {
case 0:
view = li.inflate(R.layout.fragment_learn, container, false);
break;
case 1:
view = li.inflate(R.layout.fragment_home, container, false);
break;
case 2:
view = li.inflate(R.layout.fragment_challenges, container, false);
break;
}
// Add the newly created View to the ViewPager
container.addView(view);
// Return the View
return view;
}
/**
* {@link View}.
*/
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
}
这是活动的主要xml代码：
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/sample_main_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@color/color1">
<TextView
android:id="@+id/toolbar_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="@string/app_name"
android:textColor="@color/white"
android:textSize="@dimen/text_size_in_toolbar" />
</android.support.v7.widget.Toolbar>
<android.support.design.widget.TabLayout
android:id="@+id/tablayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/color1">
</android.support.design.widget.TabLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="0px"
android:layout_weight="1"
android:background="@android:color/white" />
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>