我正在开发一款Android应用。在我的应用程序中，我正在使用Recycler View。这是我第一次使用Recycler View。我和CardView一起使用它。我使用Recycler视图的原因是我想通过向左或向右滑动来删除行。但我无法在Recycler View中找到事件。我怎么设置它？它内置于Recycler View中吗？
我使用像这样的爷爷安装了
compile 'com.android.support:cardview-v7:23.0.+'
compile 'com.android.support:recyclerview-v7:23.0.+'
这是我的适配器
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.MyViewHolder> {
private ArrayList<CardData> values;
public CardAdapter(ArrayList<CardData> valuesPram)
{
this.values = valuesPram;
}
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView name,email;
public MyViewHolder(View view) {
super(view);
name = (TextView) view.findViewById(R.id.card_name);
email = (TextView)view.findViewById(R.id.card_email);
}
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.cards_layout, parent, false);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
CardData cardData = values.get(position);
holder.email.setText(cardData.getEmail());
holder.name.setText(cardData.getName());
}
@Override
public int getItemCount() {
return values.size();
}
}
这是我的行布局
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardBackgroundColor="@color/colorAccent"
card_view:cardCornerRadius="10dp"
card_view:cardElevation="5dp"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto">
<LinearLayout
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<TextView
android:id="@+id/card_name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/card_email"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</android.support.v7.widget.CardView>
这是我的活动
public class MainActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private ArrayList<Integer> removedItems;
private ArrayList<CardData> listItems;
private CardAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initializeData();
setUpRecyclerView();
}
private void setUpRecyclerView()
{
recyclerView = (RecyclerView)findViewById(R.id.my_recycler_view);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(adapter);
}
private void initializeData()
{
listItems = new ArrayList<CardData>();
CardData item1 = new CardData();
item1.setName("Name 1");
item1.setEmail("Email 1");
listItems.add(item1);
CardData item2 = new CardData();
item2.setName("Name 2");
item2.setEmail("Email 2");
listItems.add(item2);
CardData item3 = new CardData();
item3.setName("Name 3");
item3.setEmail("Email 3");
listItems.add(item3);
CardData item4 = new CardData();
item4.setName("Name 4");
item4.setEmail("Email 4");
listItems.add(item4);
adapter = new CardAdapter(listItems);
}
private void removeItem(View v)
{
int selectedItemPosition = recyclerView.getChildPosition(v);
RecyclerView.ViewHolder viewHolder = recyclerView.findViewHolderForPosition(selectedItemPosition);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
我的代码工作正常。我的问题是如何通过向左或向右滑动其中一行回收者视图来实现删除项目的事件？
答案 0 :(得分：3)
一个简单的解决方案是使用RecyclerView本身提供的ItemTouchHelper
//Swipe to Delete
ItemTouchHelper swipeToDismissTouchHelper = new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(
ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
return false;
}
@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction)
{
// Do Stuff
}
});
swipeToDismissTouchHelper.attachToRecyclerView(recyclerView);
答案 1 :(得分：1)
@iPaulPro开发了一小段名为ItemTouchHelper的代码。它非常完美，支持几乎任何RecyclerView的拖动和滑动。您只需要实现3个简单的接口+稍微重写的回调类（在简单的情况下，工程提供了回调类）。
答案 2 :(得分：0)
将此类添加到项目中 SwipeDismissRecyclerViewTouchListener 在您的活动中添加以下行
SwipeDismissRecyclerViewTouchListener touchListener =
new SwipeDismissRecyclerViewTouchListener(
recyclerObject,
new SwipeDismissRecyclerViewTouchListener.DismissCallbacks() {
@Override
public boolean canDismiss(int position) {
return true;
}
@Override
public void onDismiss(RecyclerView recyclerView, int[] reverseSortedPositions) {
for (final int position : reverseSortedPositions) {
your_array.remove(position);
}
// do not call notifyItemRemoved for every item, it will cause gaps on deleting items
adapter.notifyDataSetChanged();
}
});
recyclerObject.setOnTouchListener(touchListener);
SwipeDismissRecyclerViewTouchListener
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
import android.graphics.Rect;
import android.os.SystemClock;
import android.support.v7.widget.RecyclerView;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class SwipeDismissRecyclerViewTouchListener implements View.OnTouchListener {
// Cached ViewConfiguration and system-wide constant values
private int mSlop;
private int mMinFlingVelocity;
private int mMaxFlingVelocity;
private long mAnimationTime;
// Fixed properties
private RecyclerView mRecyclerView;
private DismissCallbacks mCallbacks;
private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero
// Transient properties
private List<PendingDismissData> mPendingDismisses = new ArrayList<PendingDismissData>();
private int mDismissAnimationRefCount = 0;
private float mDownX;
private float mDownY;
private boolean mSwiping;
private int mSwipingSlop;
private VelocityTracker mVelocityTracker;
private int mDownPosition;
private View mDownView;
private boolean mPaused;
/**
* The callback interface used by {@link coverflow.example.bala.myrecyclerview.SwipeDismissRecyclerViewTouchListener} to inform its client
* about a successful dismissal of one or more list item positions.
*/
public interface DismissCallbacks {
/**
* Called to determine whether the given position can be dismissed.
*/
boolean canDismiss(int position);
/**
* Called when the user has indicated they she would like to dismiss one or more list item
* positions.
*
* @param recyclerView The originating {@link ListView}.
* @param reverseSortedPositions An array of positions to dismiss, sorted in descending
* order for convenience.
*/
void onDismiss(RecyclerView recyclerView, int[] reverseSortedPositions);
}
/**
* Constructs a new swipe-to-dismiss touch listener for the given list view.
*
* @param recyclerView The list view whose items should be dismissable.
* @param callbacks The callback to trigger when the user has indicated that she would like to
* dismiss one or more list items.
*/
public SwipeDismissRecyclerViewTouchListener(RecyclerView recyclerView, DismissCallbacks callbacks) {
ViewConfiguration vc = ViewConfiguration.get(recyclerView.getContext());
mSlop = vc.getScaledTouchSlop();
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
mAnimationTime = recyclerView.getContext().getResources().getInteger(
android.R.integer.config_shortAnimTime);
mRecyclerView = recyclerView;
mCallbacks = callbacks;
}
/**
* Enables or disables (pauses or resumes) watching for swipe-to-dismiss gestures.
*
* @param enabled Whether or not to watch for gestures.
*/
public void setEnabled(boolean enabled) {
mPaused = !enabled;
}
/**
* Returns an {@link AbsListView.OnScrollListener} to be added to the {@link
* ListView} using {@link ListView#setOnScrollListener(AbsListView.OnScrollListener)}.
* If a scroll listener is already assigned, the caller should still pass scroll changes through
* to this listener. This will ensure that this {@link coverflow.example.bala.myrecyclerview.SwipeDismissRecyclerViewTouchListener} is
* paused during list view scrolling.</p>
*
* @see coverflow.example.bala.myrecyclerview.SwipeDismissRecyclerViewTouchListener
*/
public RecyclerView.OnScrollListener makeScrollListener() {
return new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
setEnabled(newState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
}
};
}
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
if (mViewWidth < 2) {
mViewWidth = mRecyclerView.getWidth();
}
switch (motionEvent.getActionMasked()) {
case MotionEvent.ACTION_DOWN: {
if (mPaused) {
return false;
}
// TODO: ensure this is a finger, and set a flag
// Find the child view that was touched (perform a hit test)
Rect rect = new Rect();
int childCount = mRecyclerView.getChildCount();
int[] listViewCoords = new int[2];
mRecyclerView.getLocationOnScreen(listViewCoords);
int x = (int) motionEvent.getRawX() - listViewCoords[0];
int y = (int) motionEvent.getRawY() - listViewCoords[1];
View child;
for (int i = 0; i < childCount; i++) {
child = mRecyclerView.getChildAt(i);
child.getHitRect(rect);
if (rect.contains(x, y)) {
mDownView = child;
break;
}
}
if (mDownView != null) {
mDownX = motionEvent.getRawX();
mDownY = motionEvent.getRawY();
mDownPosition = mRecyclerView.getChildPosition(mDownView);
if (mCallbacks.canDismiss(mDownPosition)) {
mVelocityTracker = VelocityTracker.obtain();
mVelocityTracker.addMovement(motionEvent);
} else {
mDownView = null;
}
}
return false;
}
case MotionEvent.ACTION_CANCEL: {
if (mVelocityTracker == null) {
break;
}
if (mDownView != null && mSwiping) {
// cancel
mDownView.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
}
mVelocityTracker.recycle();
mVelocityTracker = null;
mDownX = 0;
mDownY = 0;
mDownView = null;
mDownPosition = ListView.INVALID_POSITION;
mSwiping = false;
break;
}
case MotionEvent.ACTION_UP: {
if (mVelocityTracker == null) {
break;
}
float deltaX = motionEvent.getRawX() - mDownX;
mVelocityTracker.addMovement(motionEvent);
mVelocityTracker.computeCurrentVelocity(1000);
float velocityX = mVelocityTracker.getXVelocity();
float absVelocityX = Math.abs(velocityX);
float absVelocityY = Math.abs(mVelocityTracker.getYVelocity());
boolean dismiss = false;
boolean dismissRight = false;
if (Math.abs(deltaX) > mViewWidth / 2 && mSwiping) {
dismiss = true;
dismissRight = deltaX > 0;
} else if (mMinFlingVelocity <= absVelocityX && absVelocityX <= mMaxFlingVelocity
&& absVelocityY < absVelocityX && mSwiping) {
// dismiss only if flinging in the same direction as dragging
dismiss = (velocityX < 0) == (deltaX < 0);
dismissRight = mVelocityTracker.getXVelocity() > 0;
}
if (dismiss && mDownPosition != ListView.INVALID_POSITION) {
// dismiss
final View downView = mDownView; // mDownView gets null'd before animation ends
final int downPosition = mDownPosition;
++mDismissAnimationRefCount;
mDownView.animate()
.translationX(dismissRight ? mViewWidth : -mViewWidth)
.alpha(0)
.setDuration(mAnimationTime)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
performDismiss(downView, downPosition);
}
});
} else {
// cancel
mDownView.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
}
mVelocityTracker.recycle();
mVelocityTracker = null;
mDownX = 0;
mDownY = 0;
mDownView = null;
mDownPosition = ListView.INVALID_POSITION;
mSwiping = false;
break;
}
case MotionEvent.ACTION_MOVE: {
if (mVelocityTracker == null || mPaused) {
break;
}
mVelocityTracker.addMovement(motionEvent);
float deltaX = motionEvent.getRawX() - mDownX;
float deltaY = motionEvent.getRawY() - mDownY;
if (Math.abs(deltaX) > mSlop && Math.abs(deltaY) < Math.abs(deltaX) / 2) {
mSwiping = true;
mSwipingSlop = (deltaX > 0 ? mSlop : -mSlop);
mRecyclerView.requestDisallowInterceptTouchEvent(true);
// Cancel ListView's touch (un-highlighting the item)
MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
cancelEvent.setAction(MotionEvent.ACTION_CANCEL |
(motionEvent.getActionIndex()
<< MotionEvent.ACTION_POINTER_INDEX_SHIFT));
mRecyclerView.onTouchEvent(cancelEvent);
cancelEvent.recycle();
}
if (mSwiping) {
mDownView.setTranslationX(deltaX - mSwipingSlop);
mDownView.setAlpha(Math.max(0f, Math.min(1f,
1f - 2f * Math.abs(deltaX) / mViewWidth)));
return true;
}
break;
}
}
return false;
}
class PendingDismissData implements Comparable<PendingDismissData> {
public int position;
public View view;
public PendingDismissData(int position, View view) {
this.position = position;
this.view = view;
}
@Override
public int compareTo(PendingDismissData other) {
// Sort by descending position
return other.position - position;
}
}
private void performDismiss(final View dismissView, final int dismissPosition) {
// Animate the dismissed list item to zero-height and fire the dismiss callback when
// all dismissed list item animations have completed. This triggers layout on each animation
// frame; in the future we may want to do something smarter and more performant.
final ViewGroup.LayoutParams lp = dismissView.getLayoutParams();
final int originalHeight = dismissView.getHeight();
ValueAnimator animator = ValueAnimator.ofInt(originalHeight, 1).setDuration(mAnimationTime);
animator.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
--mDismissAnimationRefCount;
if (mDismissAnimationRefCount == 0) {
// No active animations, process all pending dismisses.
// Sort by descending position
Collections.sort(mPendingDismisses);
int[] dismissPositions = new int[mPendingDismisses.size()];
for (int i = mPendingDismisses.size() - 1; i >= 0; i--) {
dismissPositions[i] = mPendingDismisses.get(i).position;
}
mCallbacks.onDismiss(mRecyclerView, dismissPositions);
// Reset mDownPosition to avoid MotionEvent.ACTION_UP trying to start a dismiss
// animation with a stale position
mDownPosition = ListView.INVALID_POSITION;
ViewGroup.LayoutParams lp;
for (PendingDismissData pendingDismiss : mPendingDismisses) {
// Reset view presentation
pendingDismiss.view.setAlpha(1f);
pendingDismiss.view.setTranslationX(0);
lp = pendingDismiss.view.getLayoutParams();
lp.height = originalHeight;
pendingDismiss.view.setLayoutParams(lp);
}
// Send a cancel event
long time = SystemClock.uptimeMillis();
MotionEvent cancelEvent = MotionEvent.obtain(time, time,
MotionEvent.ACTION_CANCEL, 0, 0, 0);
mRecyclerView.dispatchTouchEvent(cancelEvent);
mPendingDismisses.clear();
}
}
});
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
lp.height = (Integer) valueAnimator.getAnimatedValue();
dismissView.setLayoutParams(lp);
}
});
mPendingDismisses.add(new PendingDismissData(dismissPosition, dismissView));
animator.start();
}
}
答案 3 :(得分：0)
我认为这对你有帮助
val simpleCallback: ItemTouchHelper.SimpleCallback =
object : ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {
override fun onMove(
recyclerView: RecyclerView,
viewHolder: RecyclerView.ViewHolder,
target: RecyclerView.ViewHolder
): Boolean {
return false
}
override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
val position = viewHolder.adapterPosition //get position which is swipe
if (direction == ItemTouchHelper.LEFT) { //if swipe left
val builder: AlertDialog.Builder =
AlertDialog.Builder(this@Activity) //alert for confirm to delete
builder.setMessage("Are you sure to delete?") //set message
builder.setPositiveButton("REMOVE",
DialogInterface.OnClickListener { dialog, which ->
return@OnClickListener
}).setNegativeButton("CANCEL",
DialogInterface.OnClickListener { dialog, which ->
return@OnClickListener
}).show()
}
}
}
val itemTouchHelper = ItemTouchHelper(simpleCallback)
itemTouchHelper.attachToRecyclerView(binding.recycler)