| 知乎专栏 |
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.cardview.widget.CardView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:cardCornerRadius="10dp"
app:cardElevation="0dp"
tools:ignore="MissingConstraints">
<ImageView
android:id="@+id/imageView7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="fitXY"
app:srcCompat="@drawable/bg_repast_menu" />
</androidx.cardview.widget.CardView>
</androidx.constraintlayout.widget.ConstraintLayout>
linearLayoutManager = new LinearLayoutManager(ContextHolder.getContext());
linearLayoutManager.setStackFromEnd(true);
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.scrollToPosition(adapter.getItemCount() - 1);
调用下面函数
recyclerView.smoothScrollToPosition(adapter.getItemCount() - 1);
其他用法
// linearLayoutManager.scrollToPositionWithOffset(adapter.getItemCount() - 1, Integer.MIN_VALUE); // linearLayoutManager.scrollToPosition(adapter.getItemCount() - 1);
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
// View view = View.inflate(MainApplication.getContext(), R.layout.recycler_view_chat, null); 这种方式，Item 不会100%充满屏幕
View view = LayoutInflater.from(MainApplication.getContext()).inflate(R.layout.recycler_view_chat, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
判断是否滑动到顶部/底部：
@Override
public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
if(newState == RecyclerView.SCROLL_STATE_IDLE){//停止滑动
if(recyclerView.canScrollVertically(1)){
Log.d(TAG, "滑动到顶部");
}
if(recyclerView.canScrollVertically(-1)){
Log.d(TAG, "滑动到底部");
}
}
super.onScrollStateChanged(recyclerView, newState);
}
recyclerView.canScrollVertically(1); false表示不能往上滑动，即代表到顶部了；
recyclerView.canScrollVertically(-1); false表示不能往下滑动，即代表到底部了；
判断滑动方向
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
if (dy > 0) {//下滑动作
}
if (dy < 0) {//上滑动作
}
super.onScrolled(recyclerView, dx, dy);
}
保存滚动条位置
// Save state Parcelable recyclerViewState = recyclerView.getLayoutManager().onSaveInstanceState(); // Todo // Restore state recyclerView.getLayoutManager().onRestoreInstanceState(recyclerViewState);
View view = binding.recyclerView.getChildAt(0);
TextView textView = view.findViewById(R.id.textViewQuestion);
textView.setText("Hello");
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(requireContext(), LinearLayoutManager.HORIZONTAL, false); binding.recyclerView.setLayoutManager(linearLayoutManager);
RecyclerView.LayoutManager layoutManager = binding.loraRecyclerView.getLayoutManager();
int childCount = layoutManager.getChildCount();
for (int i = 0; i < childCount; i++) {
View childView = layoutManager.getChildAt(i);
TextView nameTextView = childView.findViewById(R.id.nameTextView);
nameTextView.setBackgroundColor(Color.WHITE);
nameTextView.setTextColor(Color.BLACK);
}
<com.google.android.material.navigation.NavigationView
android:id="@+id/navigationView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
app:headerLayout="@layout/navigation_header"
app:menu="@menu/navigation" />
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<!-- <group android:checkableBehavior="single">-->
<!-- <item-->
<!-- android:id="@+id/fragment_05"-->
<!-- android:title="界面1" />-->
<!-- <item-->
<!-- android:id="@+id/fragment_06"-->
<!-- android:title="界面2" />-->
<!-- <item-->
<!-- android:id="@+id/fragment_07"-->
<!-- android:title="界面3" />-->
<!-- </group>-->
<group android:id="@+id/groupAi">
<item
android:id="@+id/fragment_share"
android:icon="@drawable/menu_community"
android:title="@string/discovery" />
<item
android:id="@+id/menu_story"
android:icon="@drawable/menu_story"
android:title="@string/story" />
<item
android:id="@+id/menu_chat"
android:icon="@drawable/menu_chat"
android:title="@string/chat" />
</group>
<group android:id="@+id/debug" android:visible="false">
<item
android:id="@+id/fragment_09"
android:icon="@drawable/menu_like"
android:title="点赞作品" />
<item
android:id="@+id/menu_home"
android:icon="@drawable/menu_favorites"
android:title="收藏作品"/>
<!-- </group>-->
<!-- <group android:id="@+id/group_two" >-->
<item
android:id="@+id/menu_pictur_book"
android:icon="@drawable/menu_book"
android:title="@string/pictur_book"
/>
</group>
<group android:id="@+id/groupSetting">
<item
android:id="@+id/fragment_bind"
android:icon="@drawable/menu_bind"
android:title="@string/device" />
<item
android:id="@+id/fragment_notification"
android:icon="@android:drawable/ic_popup_reminder"
android:title="消息通知" />
<item
android:id="@+id/menu_about"
android:icon="?android:attr/actionModeFindDrawable"
android:title="@string/about" />
<item
android:id="@+id/menu_quit"
android:icon="@drawable/menu_quit"
android:title="退出" />
</group>
</menu>
只显示图标，不显示文字 app:labelVisibilityMode="unlabeled"
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/nav_view"
android:layout_width="match_parent"
android:layout_height="40dp"
android:background="@android:color/system_neutral2_50"
app:itemIconTint="@drawable/navigation_view"
app:labelVisibilityMode="unlabeled"
app:menu="@menu/bottom_nav_menu"
tools:ignore="NewApi" />
.setLabelVisibilityMode(LabelVisibilityMode.LABEL_VISIBILITY_LABELED);
图标不显示原始颜色
setItemIconTintList(null)
文字上下移动，app:itemPaddingBottom="15dp"，app:itemPaddingTop="0dp"
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/nav_view"
android:layout_width="match_parent"
android:layout_height="40dp"
android:background="@android:color/system_neutral2_50"
android:gravity="center"
app:itemPaddingBottom="15dp"
app:itemTextColor="@color/black"
app:labelVisibilityMode="labeled"
app:menu="@menu/bottom_nav_menu"
tools:ignore="NewApi" />
<com.google.android.material.tabs.TabLayout
android:id="@+id/tabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="消息" />
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="审核" />
</com.google.android.material.tabs.TabLayout>
<androidx.fragment.app.FragmentContainerView
android:id="@+id/fragmentContainerViewTabItem"
android:name="cn.netkiller.student.ui.message.NotificationFullscreenFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:fitsSystemWindows="true" />
binding.tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
// 页面被选中
@Override
public void onTabSelected(TabLayout.Tab tab) {
Log.d(TAG, "onTabSelected: " + tab.getText());
Fragment fragment = null;
switch (tab.getPosition()) {
// 这里我随便写了两个Fragment
case 0:
fragment = new NotificationFullscreenFragment();
break;
case 1:
fragment = new AuditFragment();
break;
}
if (fragment != null) {
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainerViewTabItem, fragment).commit();
}
}
// 页面切换到其他
@Override
public void onTabUnselected(TabLayout.Tab tab) {
Log.d(TAG, "onTabUnselected: " + tab.getText());
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
Log.d(TAG, "onTabReselected: " + tab.getText());
}
});
binding.tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
private boolean isOnTabSelectedListener = false;
@Override
public void onTabSelected(TabLayout.Tab tab) {
if (isOnTabSelectedListener) {
Log.e(TAG, "onTabSelected: 暴击 " + tab.getText());
return;
} else {
new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
public void run() {
isOnTabSelectedListener = false;
Log.e(TAG, "Tab 释放");
}
}, 5000);
isOnTabSelectedListener = true;
}
Log.d(TAG, "onTabSelected: " + tab.getText());
Fragment fragment = null;
switch (tab.getPosition()) {
case 0:
fragment = new NoticeFragment();
break;
case 1:
fragment = new MessageFragment();
break;
case 2:
fragment = new AuditFragment();
break;
}
if (fragment != null) {
try {
if (!isAdded()) return;
// requireActivity().getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainerViewTabItem, fragment).commit();
getChildFragmentManager().beginTransaction().replace(R.id.fragmentContainerViewTabItem, fragment).commitAllowingStateLoss();
} catch (Exception e) {
Log.d(TAG, "Tab 切换出错" + e.getMessage());
}
}
}
// 页面切换到其他
@Override
public void onTabUnselected(TabLayout.Tab tab) {
Log.d(TAG, "onTabUnselected: " + tab.getText());
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
Log.d(TAG, "onTabReselected: " + tab.getText());
}
});
增加间隔时间，并且恢复最后一次点击位置的操作
private void switchTabLayout(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = new NoticeFragment();
break;
case 1:
fragment = new MessageFragment();
break;
case 2:
fragment = new AuditFragment();
break;
}
if (fragment != null) {
try {
if (!isAdded()) return;
// requireActivity().getSupportFragmentManager().beginTransaction().replace(R.id.fragmentContainerViewTabItem, fragment).commit();
getChildFragmentManager().beginTransaction().replace(R.id.fragmentContainerViewTabItem, fragment).commitAllowingStateLoss();
} catch (Exception e) {
Log.d(TAG, "Tab 切换出错" + e.getMessage());
}
}
}
binding.tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
private final long interval = 1000L;
private boolean isOnTabSelectedListener = false;
private int index = 0;
@Override
public void onTabSelected(TabLayout.Tab tab) {
index = tab.getPosition();
if (isOnTabSelectedListener) {
Log.e(TAG, "onTabSelected: 暴击 " + tab.getText() + " 位置: " + index);
return;
} else {
new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
public void run() {
isOnTabSelectedListener = false;
switchTabLayout(index);
Log.e(TAG, "Tab 释放，并且切换最后一次点击位置: " + index + " - " + tab.getPosition());
}
}, interval);
isOnTabSelectedListener = true;
}
Log.d(TAG, "onTabSelected: " + tab.getText());
switchTabLayout(tab.getPosition());
}
// 页面切换到其他
@Override
public void onTabUnselected(TabLayout.Tab tab) {
Log.d(TAG, "onTabUnselected: " + tab.getText());
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
Log.d(TAG, "onTabReselected: " + tab.getText());
}
});
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/viewPager2"
android:layout_width="match_parent"
android:layout_height="match_parent" />
view_page_layout.xml 文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="TextView" />
</LinearLayout>
private List<String> items = List.of("A", "B", "C");
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
binding.viewPager2.setAdapter(new ViewPagerAdapter());
}
public class ViewPagerAdapter extends RecyclerView.Adapter<ViewPagerAdapter.CardViewHolder> {
@NonNull
@Override
public ViewPagerAdapter.CardViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
return new CardViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.view_page_layout, parent, false));
}
@Override
public void onBindViewHolder(@NonNull ViewPagerAdapter.CardViewHolder holder, int position) {
holder.textView.setText(items.get(position));
}
@Override
public int getItemCount() {
return items.size();
}
public class CardViewHolder extends RecyclerView.ViewHolder {
public TextView textView;
public CardViewHolder(@NonNull View itemView) {
super(itemView);
textView = itemView.findViewById(R.id.textView);
}
}
}
<com.google.android.material.tabs.TabLayout
android:id="@+id/tabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="推荐" />
</com.google.android.material.tabs.TabLayout>
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/viewPager2"
android:layout_width="match_parent"
android:layout_height="match_parent" />
package cn.netkiller.student.fragment.library;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.viewpager2.adapter.FragmentStateAdapter;
import com.google.gson.Gson;
import java.util.List;
import cn.netkiller.student.cloud.PictureBook;
import cn.netkiller.student.databinding.FragmentLibraryFullscreenBinding;
public class LibraryFullscreenFragment extends Fragment {
private static final String TAG = LibraryFullscreenFragment.class.getSimpleName();
private final Gson gson = new Gson();
private FragmentLibraryFullscreenBinding binding;
private List<PictureBook.DataResponse.Data> categories;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater,
@Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
binding = FragmentLibraryFullscreenBinding.inflate(inflater, container, false);
return binding.getRoot();
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
PictureBook pictureBook = new PictureBook();
pictureBook.category(datas -> {
categories = datas;
requireActivity().runOnUiThread(() -> {
categories.forEach(item -> {
var tab = binding.tabLayout.newTab();
tab.setText(item.name);
binding.tabLayout.addTab(tab);
});
binding.viewPager2.setAdapter(new ViewPagerFragmentStateAdapter(this));
});
});
}
public class ViewPagerFragmentStateAdapter extends FragmentStateAdapter {
public ViewPagerFragmentStateAdapter(@NonNull Fragment fragment) {
super(fragment);
}
@NonNull
@Override
public Fragment createFragment(int position) {
int id = categories.get(position).id;
return BookshelfFragment.newInstance(id);
}
@Override
public int getItemCount() {
return categories.size();
}
}
@Override
public void onResume() {
super.onResume();
}
@Override
public void onPause() {
super.onPause();
}
@Override
public void onDestroy() {
super.onDestroy();
}
@Override
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
}
package cn.netkiller.student.fragment.library;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import cn.netkiller.student.databinding.FragmentBookshelfBinding;
public class BookshelfFragment extends Fragment {
private static final String TAG = BookshelfFragment.class.getSimpleName();
private FragmentBookshelfBinding binding;
private int categoryId;
public static BookshelfFragment newInstance(int categoryId) {
BookshelfFragment fragment = new BookshelfFragment();
Bundle args = new Bundle();
args.putInt("categoryId", categoryId);
// args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater,
@Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
binding = FragmentBookshelfBinding.inflate(inflater, container, false);
if (getArguments() != null) {
categoryId = getArguments().getInt("categoryId");
}
return binding.getRoot();
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Log.d(TAG, "Categroy Id: " + categoryId);
binding.fullscreenContent.setText(categoryId + "");
}
@Override
public void onResume() {
super.onResume();
}
@Override
public void onPause() {
super.onPause();
}
@Override
public void onDestroy() {
super.onDestroy();
}
@Override
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
PictureBook pictureBook = new PictureBook();
pictureBook.category(datas -> {
categories = datas;
requireActivity().runOnUiThread(() -> {
categories.forEach(item -> {
var tab = binding.tabLayout.newTab();
tab.setText(item.name);
binding.tabLayout.addTab(tab);
});
binding.viewPager2.setAdapter(new ViewPagerFragmentStateAdapter(this));
new TabLayoutMediator(binding.tabLayout, binding.viewPager2, new TabLayoutMediator.TabConfigurationStrategy() {
@Override
public void onConfigureTab(@NonNull TabLayout.Tab tab, int position) {
tab.setText(categories.get(position).name);
}
}).attach();
});
});
}