所以我正在尝试实现一个 FAB 按钮，这样当我滚动我的回收器 View 并且第一个项目不可见(向上滚动等)时，fab 按钮应该是可见的，否则如果第一个位置是它应该隐藏显示。现在我已经实现了代码，但它根本没有显示 fab 按钮，只是想知道我做错了什么？
我的 xml 代码如下:
<Linearlayout ....
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/pullToRefreshLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/myRecyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</android.support.v4.widget.SwipeRefreshLayout>
<android.support.design.widget.FloatingActionButton
android:id="@+id/emailFab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="16dp"
android:src="@android:drawable/ic_dialog_email"
app:layout_anchor="@id/myRecyclerView"
android:layout_gravity="bottom|end"
app:layout_behavior="com.example.fab.ScrollAwareFABBehavior"
app:layout_anchorGravity="bottom|end"
/>
</FrameLayout>
</LinearLayout>
我的 Kotlin 代码如下:
val positionView = (myRecyclerView.getLayoutManager() as LinearLayoutManager).findFirstVisibleItemPosition()
myRecyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
if (dy >0 && positionView > 0) {
emailFab.show();
} else {
emailFab.hide();
}
}
有什么想法吗？
谢谢!
最佳答案
此代码 100% 有效:
public class TestActivity extends AppCompatActivity {
private static final String TAG = "TestActivity";
private ArrayList<String> datas = new ArrayList<>();
private FloatingActionButton fabButton;
private RecyclerView recyclerView;
private LinearLayoutManager linearLayoutManager;
private DataAdapter dataAdapter;
private boolean isFabVisible = false;
private OnFabVisibilityCallback onFabVisibilityCallback;
public void setOnFabVisibilityCallback(OnFabVisibilityCallback onFabVisibilityCallback) {
this.onFabVisibilityCallback = onFabVisibilityCallback;
}
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_contacts);
datas.add("one");
datas.add("two");
datas.add("three");
datas.add("four");
datas.add("five");
datas.add("six");
datas.add("seven");
datas.add("eight");
datas.add("nine");
datas.add("ten");
fabButton = (FloatingActionButton)findViewById(R.id.fabButton);
fabButton.setVisibility(View.GONE);
recyclerView = (RecyclerView)findViewById(R.id.recyclerView);
linearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
recyclerView.setLayoutManager(linearLayoutManager);
dataAdapter = new DataAdapter(this, datas);
recyclerView.setAdapter(dataAdapter);
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
if(linearLayoutManager.findFirstVisibleItemPosition() == 0){
//hide
if(onFabVisibilityCallback != null){
onFabVisibilityCallback.onChange(false);
}
}else{
//show
if(onFabVisibilityCallback != null){
onFabVisibilityCallback.onChange(true);
}
}
}
});
setOnFabVisibilityCallback(new OnFabVisibilityCallback() {
@Override
public void onChange(boolean isVisible) {
if(isVisible){
if(!isFabVisible){
isFabVisible = true;
fabButton.setVisibility(View.VISIBLE);
}
}else{
if(isFabVisible){
isFabVisible = false;
fabButton.setVisibility(View.GONE);
}
}
}
});
}
private class DataAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{
private Activity activity;
private ArrayList<String> datas;
private LayoutInflater layoutInflater;
public DataAdapter(Activity activity, ArrayList<String> datas) {
this.activity = activity;
this.datas = datas;
this.layoutInflater = LayoutInflater.from(activity);
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
return new SimpleViewHolder(layoutInflater.inflate(R.layout.unit_test, parent, false));
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
((SimpleViewHolder)holder).init(datas.get(position));
}
@Override
public int getItemCount() {
return datas.size();
}
private class SimpleViewHolder extends RecyclerView.ViewHolder{
private TextView text;
public SimpleViewHolder(View itemView) {
super(itemView);
initViews(itemView);
}
private void initViews(View v){
text = (TextView)v.findViewById(R.id.text);
}
public void init(String data){
text.setText(data);
}
}
}
public interface OnFabVisibilityCallback{
void onChange(boolean isVisible);
}
}
Activity 布局文件:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<android.support.design.widget.FloatingActionButton
android:id="@+id/fabButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_margin="16dp"
android:src="@drawable/ic_add_black_24dp"
android:tint="@color/white" />
</RelativeLayout>
这是 recyclerview 子布局:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:gravity="center"
android:background="@color/yellow"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="150dp">
<TextView
android:text="data"
android:id="@+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
关于android - 当回收站 View 中的第一项不可见但在第一项可见时隐藏时，如何在滚动上显示我的工厂？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53381083/