RecyclerView is an advanced version of ListView with improved performance. When you have a long list of items to show you can use RecyclerView. It has the ability to reuse its views. In RecyclerView when the View goes out of the screen or is not visible to the user it won’t destroy it, it will reuse these views. This feature helps in reducing power consumption and providing more responsiveness to the application. In this article, we are going to see that how we can delete multiple items from a recycler view in android studio. Before moving further let us know about RecyclerView.
Prerequisites:
Before implementing the concept taught in this article, you should have the knowledge of implementing a recycler view in android studio. If you don’t know how to implement a recycler view then go through the following article: RecyclerView in Android with Example
What we are going to build in this article?
Here is a sample video of what we are going to implement in this article. Note that we are going to implement this application using Java language.
Step by Step Implementation
Step 1: Create a New Project
- Open a new project.
- We will be working on Empty Activity with language as Java. Leave all other options unchanged.
- You can change the name of the project at your convenience.
- There will be two default files named activity_main.xml and MainActivity.java.
If you don’t know how to create a new project in Android Studio then you can refer to How to Create/Start a New Project in Android Studio?
Step 2: Adding the required dependencies
Open Gradle Scripts > build.gradle(module). Go to app > right click > open module settings > dependencies > Add dependency > Library dependency.
Type material in the search bar and click on search. Select the dependency shown in the below image-
Type “lifecycle-extensions” in the search bar and click on search. Select the dependency shown in the below image-
Step 3: Add new vector assets in drawable
Navigate to drawable > right-click > new > vector asset and then select the following assets from clip art.
1. Check circle:
2. Select all:
Step 4: Working with xml files
Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file.
XML
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <androidx.recyclerview.widget.RecyclerView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/recycler_view" tools:listitem="@layout/item_main" /> <TextView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/tv_empty" android:text="No Data Found" android:textSize="24sp" android:textStyle="bold" android:textColor="@color/design_default_color_primary" android:gravity="center" android:visibility="gone" /> </androidx.constraintlayout.widget.ConstraintLayout> |
Follow the path app > res > layout > right click > new > layout resource file and create a new file named as item_main.xml. Use the below code in item_main.xml file-
XML
<?xml version="1.0" encoding="utf-8"?><LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:padding="4dp" android:layout_gravity="center" > <TextView android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:id="@+id/text_view" android:padding="12dp" /> <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/check_box" android:layout_marginStart="12dp" android:layout_marginEnd="12dp" android:visibility="gone" android:src="@drawable/ic_check_circle" /> </LinearLayout> |
Follow the path app > res > right click > new > android resource file > Resource type > menu and create a new file named as menu.xml. Use the below code in menu.xml file-
XML
<?xml version="1.0" encoding="utf-8"?> <item android:id="@+id/menu_delete" android:title="Delete" android:icon="@drawable/ic_delete" app:showAsAction="always" /> <item android:id="@+id/menu_select_all" android:title="Select all" android:icon="@drawable/ic_select_all" app:showAsAction="always"/></menu> |
Step 5: Working with java files
Go to the MainActivity.java file and refer to the following code. Below is the code for the MainActivity.java file. Comments are added inside the code to understand the code in more detail.
Java
package com.example.multiple_item_delete; import androidx.appcompat.app.AppCompatActivity;import androidx.recyclerview.widget.LinearLayoutManager;import androidx.recyclerview.widget.RecyclerView; import android.os.Bundle;import android.widget.TextView; import java.util.ArrayList;import java.util.Arrays; public class MainActivity extends AppCompatActivity { // initialize variables RecyclerView recyclerView; TextView tvEmpty; ArrayList<String> arrayList=new ArrayList<>(); MainAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // assign variable recyclerView=findViewById(R.id.recycler_view); tvEmpty=findViewById(R.id.tv_empty); // add values in arraylist arrayList.addAll(Arrays.asList("One","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Eleven" ,"Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen","Twenty")); // set layout manager recyclerView.setLayoutManager(new LinearLayoutManager(this)); // Initialize adapter adapter=new MainAdapter(this,arrayList,tvEmpty); // set adapter recyclerView.setAdapter(adapter); }} |
Follow the path app > java > com.example.multiple_item_delete > right click > new > java class and create a new file named as MainAdapter.java. Use the below code in MainAdapter.java file-
Java
package com.example.multiple_item_delete; import android.app.Activity;import android.graphics.Color;import android.text.Layout;import android.view.ActionMode;import android.view.LayoutInflater;import android.view.Menu;import android.view.MenuInflater;import android.view.MenuItem;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.TextView;import android.widget.Toast; import androidx.annotation.NonNull;import androidx.appcompat.app.AppCompatActivity;import androidx.fragment.app.FragmentActivity;import androidx.lifecycle.LifecycleOwner;import androidx.lifecycle.Observer;import androidx.lifecycle.ViewModelProviders;import androidx.recyclerview.widget.RecyclerView; import java.util.ArrayList; public class MainAdapter extends RecyclerView.Adapter<MainAdapter.ViewHolder> { // initialize variables Activity activity; ArrayList<String> arrayList; TextView tvEmpty; MainViewModel mainViewModel; boolean isEnable=false; boolean isSelectAll=false; ArrayList<String> selectList=new ArrayList<>(); // create constructor public MainAdapter(Activity activity,ArrayList<String> arrayList,TextView tvEmpty) { this.activity=activity; this.arrayList=arrayList; this.tvEmpty=tvEmpty; } @NonNull @Override public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { // initialize variables View view= LayoutInflater.from(parent.getContext()). inflate(R.layout.item_main,parent,false); // initialize view Model mainViewModel= ViewModelProviders.of((FragmentActivity) activity) .get(MainViewModel.class); // return view return new ViewHolder(view); } @Override public void onBindViewHolder(@NonNull ViewHolder holder, int position) { // set text on text view holder.textView.setText(arrayList.get(position)); holder.itemView.setOnLongClickListener(new View.OnLongClickListener() { @Override public boolean onLongClick(View v) { // check condition if (!isEnable) { // when action mode is not enable // initialize action mode ActionMode.Callback callback=new ActionMode.Callback() { @Override public boolean onCreateActionMode(ActionMode mode, Menu menu) { // initialize menu inflater MenuInflater menuInflater= mode.getMenuInflater(); // inflate menu menuInflater.inflate(R.menu.menu,menu); // return true return true; } @Override public boolean onPrepareActionMode(ActionMode mode, Menu menu) { // when action mode is prepare // set isEnable true isEnable=true; // create method ClickItem(holder); // set observer on getText method mainViewModel.getText().observe((LifecycleOwner) activity , new Observer<String>() { @Override public void onChanged(String s) { // when text change // set text on action mode title mode.setTitle(String.format("%s Selected",s)); } }); // return true return true; } @Override public boolean onActionItemClicked(ActionMode mode, MenuItem item) { // when click on action mode item // get item id int id=item.getItemId(); // use switch condition switch(id) { case R.id.menu_delete: // when click on delete // use for loop for(String s:selectList) { // remove selected item list arrayList.remove(s); } // check condition if(arrayList.size()==0) { // when array list is empty // visible text view tvEmpty.setVisibility(View.VISIBLE); } // finish action mode mode.finish(); break; case R.id.menu_select_all: // when click on select all // check condition if(selectList.size()==arrayList.size()) { // when all item selected // set isselectall false isSelectAll=false; // create select array list selectList.clear(); } else { // when all item unselected // set isSelectALL true isSelectAll=true; // clear select array list selectList.clear(); // add value in select array list selectList.addAll(arrayList); } // set text on view model mainViewModel.setText(String .valueOf(selectList.size())); // notify adapter notifyDataSetChanged(); break; } // return true return true; } @Override public void onDestroyActionMode(ActionMode mode) { // when action mode is destroy // set isEnable false isEnable=false; // set isSelectAll false isSelectAll=false; // clear select array list selectList.clear(); // notify adapter notifyDataSetChanged(); } }; // start action mode ((AppCompatActivity) v.getContext()).startActionMode(callback); } else { // when action mode is already enable // call method ClickItem(holder); } // return true return true; } }); holder.itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // check condition if(isEnable) { // when action mode is enable // call method ClickItem(holder); } else { // when action mode is not enable // display toast Toast.makeText(activity,"You Clicked"+arrayList.get(holder.getAdapterPosition()), Toast.LENGTH_SHORT).show(); } } }); // check condition if(isSelectAll) { // when value selected // visible all check boc image holder.checkbox.setVisibility(View.VISIBLE); //set background color holder.itemView.setBackgroundColor(Color.LTGRAY); } else { // when all value unselected // hide all check box image holder.checkbox.setVisibility(View.GONE); // set background color holder.itemView.setBackgroundColor(Color.TRANSPARENT); } } private void ClickItem(ViewHolder holder) { // get selected item value String s=arrayList.get(holder.getAdapterPosition()); // check condition if(holder.checkbox.getVisibility()==View.GONE) { // when item not selected // visible check box image holder.checkbox.setVisibility(View.VISIBLE); // set background color holder.itemView.setBackgroundColor(Color.LTGRAY); // add value in select array list selectList.add(s); } else { // when item selected // hide check box image holder.checkbox.setVisibility(View.GONE); // set background color holder.itemView.setBackgroundColor(Color.TRANSPARENT); // remove value from select arrayList selectList.remove(s); } // set text on view model mainViewModel.setText(String.valueOf(selectList.size())); } @Override public int getItemCount() { return arrayList.size(); } public class ViewHolder extends RecyclerView.ViewHolder { // initialize variables TextView textView; ImageView checkbox; public ViewHolder(@NonNull View itemView) { super(itemView); // assign variables textView=itemView.findViewById(R.id.text_view); checkbox=itemView.findViewById(R.id.check_box); } }} |
Follow the path app > java > com.example.multiple_item_delete > right-click > new > java class and create a new file named as MainViewModel.java. Use the below code in MainViewModel.java file-
Java
package com.example.multiple_item_delete; import androidx.lifecycle.MutableLiveData;import androidx.lifecycle.ViewModel; public class MainViewModel extends ViewModel { // initialize variables MutableLiveData<String> mutableLiveData=new MutableLiveData<>(); // create set text method public void setText(String s) { // set value mutableLiveData.setValue(s); } // create get text method public MutableLiveData<String> getText() { return mutableLiveData; }} |
Output:
Here is the final output of our application.
