Here we will create an example to delete an item of RecyclerView by swiping the item with undo functionality. For this purpose, we will use the ItemTouchHelper class which is added in Android Support Library V7 in order to achieve swipe to delete Recycler view items with UNDO.
This class is used to create a swipe to delete the items of RecyclerView. It has a SimpleCallback class that configures the events which are performed to swipe or move the item of the RecyclerView.
ItemTouchHelper class
It is a utility class that provides the facility to add swipe to dismiss and drag & drops the items of RecyclerView. It overrides the callback methods onMove() or onSwipe() depending upon the functionality we implement. So lets try to implement Swipe to Delete RecyclerView items with UNDO
Must Read: Google Login And Registration For Android Using Firebase Authentication
Android Swipe to Delete RecyclerView items with UNDO Example
Create a MainActivity.java class with the following code.
activity_main.xml
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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"
android:fitsSystemWindows="true"
tools:context="example.androidhire.com.recyclerviewswipedeleteundo.MainActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_main" />
</android.support.design.widget.CoordinatorLayout>
content_main.xml
<fragment 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:id="@+id/fragment" android:name="example.androidhire.com.recyclerviewswipedeleteundo.MainActivityFragment"
android:layout_width="match_parent" android:layout_height="match_parent" app:layout_behavior="@string/appbar_scrolling_view_behavior" tools:layout="@layout/fragment_main" />
MainActivity.java
package example.androidhire.com.recyclerviewswipedeleteundo;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
public class MainActivity extends AppCompatActivity {
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
}
}
Create a layout regular_item.xml which appears at normal mode
regular_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/regularLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="@dimen/activity_horizontal_margin">
<TextView
android:id="@+id/list_item"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Regular Layout"
android:textSize="28sp" />
</LinearLayout> Create a layout swipe_item.xml which appears at the period of swipe item
swipe_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipeLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/swipebackground"
android:orientation="horizontal"
android:padding="@dimen/activity_horizontal_margin"
android:visibility="visible"
android:weightSum="3">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/archived_label"
android:textColor="@android:color/white"
android:textSize="24sp" />
<TextView
android:id="@+id/undo"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:gravity="end"
android:paddingBottom="5dp"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:paddingTop="5dp"
android:text="@string/undo_label"
android:textColor="@android:color/white"
android:textSize="22sp"
android:textStyle="bold" />
</LinearLayout>
customlayout.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<!-- Swipe Layout-->
<include layout="@layout/swipe_item" />
<!-- Regular Layout-->
<include layout="@layout/regular_item" />
</FrameLayout> Create a utility class SwipeUtil.java which extends the ItemTouchHelper.SimpleCallback class and overrides its onMove(), onSwiped(), onChildDraw() methods. The onSwiped() method is called when we perform swipe operation on an item, and the onChildDraw() methods contain the implementation logic of drawing canvas while swiping the items of RecyclerView.
SwipeUtil.java
1. package example.androidhire.com.recyclerviewswipedeleteundo;
2.
3. import android.content.Context;
4. import android.graphics.Canvas;
5. import android.graphics.Color;
6. import android.graphics.Paint;
7. import android.graphics.PorterDuff;
8. import android.graphics.drawable.ColorDrawable;
9. import android.graphics.drawable.Drawable;
10. import android.support.v4.content.ContextCompat;
11. import android.support.v7.widget.RecyclerView;
12. import android.support.v7.widget.helper.ItemTouchHelper;
13. import android.view.View;
14.
15. public abstract class SwipeUtil extends ItemTouchHelper.SimpleCallback {
16.
17. private Drawable background;
18. private Drawable deleteIcon;
19. private int xMarkMargin;
20. private boolean initiated;
21. private Context context;
22. private int leftcolorCode;
23. private String leftSwipeLable;
24.
25. public SwipeUtil(int dragDirs, int swipeDirs, Context context) {
26. super(dragDirs, swipeDirs);
27. this.context = context;
28. }
29.
30. private void init() {
31. background = new ColorDrawable();
32. xMarkMargin = (int) context.getResources().getDimension(R.dimen.ic_clear_margin);
33. deleteIcon = ContextCompat.getDrawable(context, android.R.drawable.ic_menu_delete);
34. deleteIcon.setColorFilter(Color.WHITE, PorterDuff.Mode.SRC_ATOP);
35. initiated = true;
36. }
37.
38. @Override
39. public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
40. return false;
41. }
42.
43. @Override
44. public abstract void onSwiped(RecyclerView.ViewHolder viewHolder, int direction);
45.
46. @Override
47. public int getSwipeDirs(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
48.
49. return super.getSwipeDirs(recyclerView, viewHolder);
50. }
51.
52. @Override
53. public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
54. float dX, float dY, int actionState, boolean isCurrentlyActive) {
View itemView = viewHolder.itemView;
if (!initiated) {
init();
}
int itemHeight = itemView.getBottom() - itemView.getTop();
//Setting Swipe Background
((ColorDrawable) background).setColor(getLeftcolorCode());
background.setBounds(itemView.getRight() + (int) dX, itemView.getTop(), itemView.getRight(), itemView.getBottom());
background.draw(c);
int intrinsicWidth = deleteIcon.getIntrinsicWidth();
int intrinsicHeight = deleteIcon.getIntrinsicWidth();
int xMarkLeft = itemView.getRight() - xMarkMargin - intrinsicWidth;
int xMarkRight = itemView.getRight() - xMarkMargin;
int xMarkTop = itemView.getTop() + (itemHeight - intrinsicHeight) / 2;
int xMarkBottom = xMarkTop + intrinsicHeight;
//Setting Swipe Icon
deleteIcon.setBounds(xMarkLeft, xMarkTop + 16, xMarkRight, xMarkBottom);
deleteIcon.draw(c);
//Setting Swipe Text
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTextSize(48);
paint.setTextAlign(Paint.Align.CENTER);
c.drawText(getLeftSwipeLable(), xMarkLeft + 40, xMarkTop + 10, paint);
super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
}
public String getLeftSwipeLable() {
return leftSwipeLable;
}
public void setLeftSwipeLable(String leftSwipeLable) {
this.leftSwipeLable = leftSwipeLable;
}
public int getLeftcolorCode() {
return leftcolorCode;
}
public void setLeftcolorCode(int leftcolorCode) {
this.leftcolorCode = leftcolorCode;
}
}
Create an ItemViewHolder.java class and extends RecyclerView.ViewHolder.
ItemViewHolder.java
1. package example.androidhire.com.recyclerviewswipedeleteundo;
2.
3. import android.support.v7.widget.RecyclerView;
4. import android.view.View;
5. import android.widget.LinearLayout;
6. import android.widget.TextView;
7.
8. public class ItemViewHolder extends RecyclerView.ViewHolder {
9.
10. public LinearLayout regularLayout;
11. public LinearLayout swipeLayout;
12. public TextView listItem;
13. public TextView undo;
14.
15. public ItemViewHolder(View view) {
16. super(view);
17.
18. regularLayout = view.findViewById(R.id.regularLayout);
19. listItem = view.findViewById(R.id.list_item);
20. swipeLayout = view.findViewById(R.id.swipeLayout);
21. undo = view.findViewById(R.id.undo);
22. }
23. }
Create an adapter class MyAdapter.java which extends the RecyclerView.Adapter class and overrides its onCreateViewHolder(), onBindViewHolder() methods.
MyAdapter.java
1. package example.androidhire.com.recyclerviewswipedeleteundo;
2.
3. import android.os.Handler;
4. import android.support.v7.widget.RecyclerView;
5. import android.view.LayoutInflater;
6. import android.view.View;
7. import android.view.ViewGroup;
8. import java.util.ArrayList;
9. import java.util.HashMap;
10. import java.util.List;
11.
12. public class MyAdapter extends RecyclerView.Adapter<ItemViewHolder> {
13.
14. private List<String> dataList;
15. private List<String> itemsPendingRemoval;
16.
17. private static final int PENDING_REMOVAL_TIMEOUT = 3000; // 3sec
18. private Handler handler = new Handler(); // hanlder for running delayed runnables
19. HashMap<String, Runnable> pendingRunnables = new HashMap<>(); // map of items to pending runnable, to cancel the removal
20.
21.
22. public MyAdapter(List<String> dataList) {
23. this.dataList = dataList;
24. itemsPendingRemoval = new ArrayList<>();
25. }
26.
27. @Override
28. public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
29. View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.customlayout, parent, false);
30. return new ItemViewHolder(itemView);
31. }
32.
33. @Override
34. public void onBindViewHolder(ItemViewHolder itemViewHolder, int position) {
35.
36. final String data = dataList.get(position);
37.
38. if (itemsPendingRemoval.contains(data)) {
39. /** show swipe layout and hide regular layout */
40. itemViewHolder.regularLayout.setVisibility(View.GONE);
41. itemViewHolder.swipeLayout.setVisibility(View.VISIBLE);
42. itemViewHolder.undo.setOnClickListener(new View.OnClickListener() {
43. @Override
44. public void onClick(View v) {
45. undoOpt(data);
46. }
47. });
48. } else {
49. /** show regular layout and hide swipe layout*/
50. itemViewHolder.regularLayout.setVisibility(View.VISIBLE);
51. itemViewHolder.swipeLayout.setVisibility(View.GONE);
52. itemViewHolder.listItem.setText(data);
53. }
54. }
55.
56. private void undoOpt(String customer) {
57. Runnable pendingRemovalRunnable = pendingRunnables.get(customer);
58. pendingRunnables.remove(customer);
59. if (pendingRemovalRunnable != null)
60. handler.removeCallbacks(pendingRemovalRunnable);
61. itemsPendingRemoval.remove(customer);
62. // this will rebind the row in "normal" state
63. notifyItemChanged(dataList.indexOf(customer));
64. }
65.
66. @Override
67. public int getItemCount() {
68. return dataList.size();
69. }
70.
71. public void pendingRemoval(int position) {
72.
73. final String data = dataList.get(position);
74. if (!itemsPendingRemoval.contains(data)) {
75. itemsPendingRemoval.add(data);
76. // this will redraw row in "undo" state
77. notifyItemChanged(position);
78. //create, store and post a runnable to remove the data
79. Runnable pendingRemovalRunnable = new Runnable() {
80. @Override
81. public void run() {
82. remove(dataList.indexOf(data));
83. }
84. };
85. handler.postDelayed(pendingRemovalRunnable, PENDING_REMOVAL_TIMEOUT);
86. pendingRunnables.put(data, pendingRemovalRunnable);
87. }
88. }
89.
90. public void remove(int position) {
91. String data = dataList.get(position);
92. if (itemsPendingRemoval.contains(data)) {
93. itemsPendingRemoval.remove(data);
94. }
95. if (dataList.contains(data)) {
96. dataList.remove(position);
97. notifyItemRemoved(position);
98. }
99. }
100.
101. public boolean isPendingRemoval(int position) {
102. String data = dataList.get(position);
103. return itemsPendingRemoval.contains(data);
104. }
105. }
Create a MainActivityFragment.java class and extends the Fragment class. In this class, set the adapter MyAdapter.java class and utility SwipeUtil.java class.
fragment_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="example.androidhire.com.recyclerviewswipedeleteundo.MainActivityFragment"
tools:showIn="@layout/activity_main">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</RelativeLayout> MainActivityFragment.java
package example.androidhire.com.recyclerviewswipedeleteundo;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.helper.ItemTouchHelper;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.List;
public class MainActivityFragment extends Fragment {
private RecyclerView mRecyclerView;
private MyAdapter myAdapter;
String[] listValue = {"C Tutorial","C++ Tutorial","Data Structure","Java Tutorial","Android Example","Kotlin Programing","Python language","Ruby Tutorial",".Net Tutorial","MySQL Database"};
public MainActivityFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View mView = inflater.inflate(R.layout.fragment_main, container, false);
mRecyclerView = mView.findViewById(R.id.recyclerView);
return mView;
}
@Override
public void onResume() {
super.onResume();
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(linearLayoutManager);
myAdapter = new MyAdapter(getData());
mRecyclerView.setAdapter(myAdapter);
setSwipeForRecyclerView();
}
private List<String> getData() {
List<String> modelList = new ArrayList<>();
for (int i = 0; i < listValue.length; i++) {
modelList.add(listValue[i]);
}
return modelList;
}
private void setSwipeForRecyclerView() {
SwipeUtil swipeHelper = new SwipeUtil(0, ItemTouchHelper.LEFT, getActivity()) {
@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
int swipedPosition = viewHolder.getAdapterPosition();
myAdapter = (MyAdapter)mRecyclerView.getAdapter();
myAdapter.pendingRemoval(swipedPosition);
}
@Override
public int getSwipeDirs(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
int position = viewHolder.getAdapterPosition();
myAdapter = (MyAdapter) mRecyclerView.getAdapter();
if (myAdapter.isPendingRemoval(position)) {
return 0;
}
return super.getSwipeDirs(recyclerView, viewHolder);
}
};
ItemTouchHelper mItemTouchHelper = new ItemTouchHelper(swipeHelper);
mItemTouchHelper.attachToRecyclerView(mRecyclerView);
//set swipe label
swipeHelper.setLeftSwipeLable("Archive");
//set swipe background-Color
swipeHelper.setLeftcolorCode(ContextCompat.getColor(getActivity(), R.color.swipebackground));
}
}strings.xml
<resources>
<string name="app_name">RecyclerView SwipeDeleteUndo</string>
<string name="action_settings">Settings</string>
<string name="hello_blank_fragment">Hello blank fragment</string>
<string name="undo_label"><u>Undo</u></string>
<string name="archived_label">Archive</string>
</resources>dimens.xml
<resources>
<dimen name="fab_margin">16dp</dimen>
<dimen name="activity_horizontal_margin">16dp</dimen>
<dimen name="activity_vertical_margin">16dp</dimen>
<dimen name="ic_clear_margin">56dp</dimen>
<dimen name="text_size_medium">20sp</dimen>
</resources> colors.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
<color name="swipebackground">#cf0b4e</color>
</resources> Outputs:
Final Words
So from the above code you would be able to implement the feature of Swipe to Delete RecyclerView items with UNDO in your android application
