Base Activity

BaseActivity is used to reuse code on the different place for the same purpose. you can see it in this tutorial.

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Steps to use BaseActivity in your project.

1. Crate a project(BaseActivityDeleteDemo) in android studio.
   
   
2. Create a Activity Activity1.Java and update it-
   
   
   

   package com.pankaj.mmm;
   import android.content.Intent;
   import android.os.Bundle;
   import android.view.View;
   import android.widget.Button;
   import android.widget.Toast;
   public class Activity1 extends BaseActivity {
       private Button btnGetSelectedTag1;
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           setContentView(R.layout.activity1);
           super.onCreate(savedInstanceState);
           //initialization
           btnGetSelectedTag1 = findViewById(R.id.btnGetSelectedTag1);
           //Add Listeners
           btnGetSelectedTag1.setOnClickListener(new View.OnClickListener() {
               @Override
               public void onClick(View v) {
                   String message = "";
                   for (String data : getSelectedTagList()) {
                       if (!data.isEmpty())
                           message += data + "\n";
                   }
                   message.trim();
                   Toast.makeText(Activity1.this, message, Toast.LENGTH_SHORT).show();
               }
           });
       }
       public void openSecondActivity(View view) {
           Intent intent = new Intent(this, Activity2.class);
           startActivity(intent);
       }
   }
   
   
   
   

    
3. Create a xml activity1.xml and update it-
   
   
   

   <?xml version="1.0" encoding="utf-8"?>
   <android.support.constraint.ConstraintLayout 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"
       tools:context="com.pankaj.mmm.BaseActivity">
   
       <LinearLayout
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:orientation="vertical">
   
           <include layout="@layout/tag_layout" />
   
           <LinearLayout
               android:layout_width="match_parent"
               android:layout_height="wrap_content">
   
               <Button
                   android:id="@+id/btnGetSelectedTag1"
                   android:layout_width="wrap_content"
                   android:layout_height="wrap_content"
                   android:layout_weight="1"
                   android:imeOptions="actionNone"
                   android:text="Show entered Data" />
   
               <Button
                   android:layout_width="wrap_content"
                   android:layout_height="wrap_content"
                   android:layout_weight="1"
                   android:imeOptions="actionNone"
                   android:onClick="openSecondActivity"
                   android:text="Open Second Screen" />
   
           </LinearLayout>
       </LinearLayout>
   </android.support.constraint.ConstraintLayout>
   
   
   
   

    
4. Create a activity Activity2.Java and update it-
   
   
   

   package com.pankaj.mmm;
   import android.os.Bundle;
   import android.view.View;
   import android.widget.Button;
   import android.widget.Toast;
   public class Activity2 extends BaseActivity {
       private Button btnGetSelectedTag2;
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           setContentView(R.layout.activity2);
           super.onCreate(savedInstanceState);
           //initialization
           btnGetSelectedTag2 = findViewById(R.id.btnGetSelectedTag2);
           //Add Listeners
           btnGetSelectedTag2.setOnClickListener(new View.OnClickListener() {
               @Override
               public void onClick(View v) {
                   String message = "";
                   for (String data : getSelectedTagList()) {
                       if (!data.isEmpty())
                           message += data + "\n";
                   }
                   message.trim();
                   Toast.makeText(Activity2.this, message, Toast.LENGTH_SHORT).show();
               }
           });
       }
   }
   
   
   
   

    
5. Create a interface CallBack.Java and update it-
   
   
   

   package com.pankaj.mmm;
   /**
    * Created by pankaj on 7/12/17.
    */
   
   public interface CallBacks {
   
       //to get event on select item
       void onSelected(String s);
   
       //to get event on delete item
       void onDeleted(int rowPosition);
   
       //to get event on done/enter click
       void onDone(String s);
   }
   
   
   
   

    
   Create a xml activity2.xml and update it-

   <?xml version="1.0" encoding="utf-8"?>
   <android.support.constraint.ConstraintLayout 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"
       tools:context="com.pankaj.mmm.BaseActivity">
   
       <LinearLayout
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:orientation="vertical">
           <include layout="@layout/tag_layout" />
   
           <Button
               android:id="@+id/btnGetSelectedTag2"
               android:layout_width="match_parent"
               android:layout_height="wrap_content"
               android:imeOptions="actionNone"
               android:text="Show entered Data" />
   
       </LinearLayout>
   </android.support.constraint.ConstraintLayout>
   
   
   
   

    
   
   
   
   
   
6. Create a activity BaseActivity.Java and update it-
   
   
   

   package com.pankaj.mmm;
   import android.os.Bundle;
   import android.support.v7.app.AppCompatActivity;
   import android.support.v7.widget.LinearLayoutManager;
   import android.support.v7.widget.RecyclerView;
   import android.view.View;
   import android.widget.Toast;
   import java.util.ArrayList;
   import java.util.List;
   
   public class BaseActivity extends AppCompatActivity implements CallBacks {
   
       //create objects
       private RecyclerView rvTagList;
       private List<String> dataSelected = new ArrayList<>();
       private List<String> dataOptions = new ArrayList<>();
       private TagAdapter tagAdapter;
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           initialization();
       }
   
       public void initialization(){
   
           //Initialize list view
           rvTagList = findViewById(R.id.rvTagList);
   
           //Create layout manager
           LinearLayoutManager manager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
   
           //Set layout manager
           rvTagList.setLayoutManager(manager);
   
           //Add data to show entry point
           dataSelected.add("");
   
           //Create suggestions
           for (int i = 0; i < 500; i++) {
               dataOptions.add("data" + i);
           }
   
           //Initialize adapter
           tagAdapter = new TagAdapter(BaseActivity.this, dataSelected, dataOptions);
   
           //Set callbacks
           tagAdapter.setCallBacks(this);
   
           //Set adapter
           rvTagList.setAdapter(tagAdapter);
       }
   
       @Override
       public void onSelected(String selected) {
   
           //Check size and put data into selecteddata list
           if (dataSelected.size() > 1) {
               dataSelected.add(dataSelected.size() - 1, selected);
           } else {
               dataSelected.add(0, selected);
           }
           scrollToLastPosition(false);
       }
   
       @Override
       public void onDeleted(int rowPosition) {
           //Delete selected item
           dataSelected.remove(rowPosition);
           scrollToLastPosition(true);
       }
   
       @Override
       public void onDone(String selected) {
   
           //Check size and put data into selecteddata list
           if (dataSelected.size() > 1) {
               dataSelected.add(dataSelected.size() - 1, selected);
           } else {
               dataSelected.add(0, selected);
           }
           scrollToLastPosition(true);
       }
   
       private void scrollToLastPosition(boolean goToLast) {
   
           //notify adapter to refresh data in it
           tagAdapter.notifyDataSetChanged();
   //        if (goToLast) rvTagList.scrollToPosition(dataSelected.size() - 1);
       }
   
       //function to show selected data
       public void selectedData(View view) {
           String message = "";
           for (String data : dataSelected) {
               if (!data.isEmpty())
                   message += data + "\n";
           }
           message.trim();
           Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
       }
   
       public List<String> getSelectedTagList() {
           return dataSelected;
       }
   }
   
   
   
   

    
7. Create a class TagAdapter.Java and update it-
   
   
   

   package com.pankaj.mmm;
   import android.app.Activity;
   import android.support.v7.widget.RecyclerView;
   import android.util.Log;
   import android.view.KeyEvent;
   import android.view.LayoutInflater;
   import android.view.View;
   import android.view.ViewGroup;
   import android.widget.AdapterView;
   import android.widget.ArrayAdapter;
   import android.widget.AutoCompleteTextView;
   import android.widget.ImageView;
   import android.widget.LinearLayout;
   import android.widget.TextView;
   import java.util.List;
   /**
    * Created by pankaj on 7/12/17.
    */
   
   public class TagAdapter extends RecyclerView.Adapter<TagAdapter.MyViewHolder> {
       //Objects
       private String TAG = "TagAdapter";
       private List<String> dataOptions;
       private List<String> dataSelected;
       private Activity activity;
       private CallBacks callBacks;
   
       /**
        * View holder class
        */
       public class MyViewHolder extends RecyclerView.ViewHolder {
           private TextView tvText;
           private ImageView ivDelete;
           private AutoCompleteTextView tvAutocomplete;
           private LinearLayout llSelected;
           public MyViewHolder(View view) {
               super(view);
               tvAutocomplete = (AutoCompleteTextView) view.findViewById(R.id.tvAutocomplete);
               tvText = (TextView) view.findViewById(R.id.tvText);
               ivDelete = (ImageView) view.findViewById(R.id.ivDelete);
               llSelected = view.findViewById(R.id.llSelected);
           }
       }
   
       //Constructor
       public TagAdapter(Activity activity, List<String> dataSelected, List<String> dataOptions) {
           this.dataSelected = dataSelected;
           this.dataOptions = dataOptions;
           this.activity = activity;
       }
   
       @Override
       public void onBindViewHolder(final MyViewHolder holder, final int rowPosition) {
           if (rowPosition != dataSelected.size() - 1) {
   
               //Set null to listeners
               holder.tvAutocomplete.setOnItemClickListener(null);
               holder.tvAutocomplete.setOnEditorActionListener(null);
   
               //selected data
               holder.llSelected.setVisibility(View.VISIBLE);
               holder.tvAutocomplete.setVisibility(View.GONE);
   
               //Set data in cells
               holder.tvText.setText(dataSelected.get(rowPosition));
   
               //Add listener to delete cells
               holder.ivDelete.setOnClickListener(new View.OnClickListener() {
   
                   @Override
                   public void onClick(View v) {
                       //send event to delete selected cell
                       callBacks.onDeleted(rowPosition);
                   }
               });
           } else {
   
               //options in autocomplete
               //Hide cells
               holder.llSelected.setVisibility(View.GONE);
               holder.tvAutocomplete.setVisibility(View.VISIBLE);
   
               //Create adapter to show suggestion
               final ArrayAdapter<String> adapter = new ArrayAdapter<String>(activity, android.R.layout.simple_dropdown_item_1line, dataOptions);
   
               //Add adapter to show suggestion
               holder.tvAutocomplete.setAdapter(adapter);
   
               //reset entry point for new entry
               holder.tvAutocomplete.setText("");
   
               //Add listener to select item from suggestion
               holder.tvAutocomplete.setOnItemClickListener(new AdapterView.OnItemClickListener() {
   
                   @Override
                   public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                       Log.e(TAG, holder.tvAutocomplete.getText() + " Position : " + position);
   
                       //send event to add selected suggestion in cells
                       callBacks.onSelected(holder.tvAutocomplete.getText().toString());
                   }
               });
   
               //Add listener to create cell of entered data
               holder.tvAutocomplete.setOnEditorActionListener(new TextView.OnEditorActionListener() {
   
                   @Override
                   public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
   
                       Log.e(TAG, "" + actionId);
   
                       //check if pressed on Ok/Done button
                       if (actionId == 6) {
                           if (holder.tvAutocomplete.getText().toString().trim().length() > 0) {
   
                               //send event to add entered text in cells
    callBacks.onDone(holder.tvAutocomplete.getText().toString().trim());
   
                               //reset entry point for new entry
                               holder.tvAutocomplete.setText("");
                           }
                       }
                       return false;
                   }
               });
           }
       }
   
       @Override
       public int getItemCount() {
           return dataSelected.size();
       }
   
       //Initialize callbacks interface
       public void setCallBacks(CallBacks callBacks) {
           this.callBacks = callBacks;
       }
   
       @Override
       public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
           View v = LayoutInflater.from(parent.getContext())
                   .inflate(R.layout.row, parent, false);
           return new MyViewHolder(v);
       }
   }
   
   
   
   

    
8. Create a xml row.xml to show individual selected item and update it-
   
   
   
   

    <?xml version="1.0" encoding="utf-8"?>
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:layout_width="wrap_content"
       android:layout_height="match_parent"
       android:minHeight="30dp">
   
       <LinearLayout
           android:id="@+id/llSelected"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_marginBottom="3dp"
           android:layout_marginLeft="3dp"
           android:layout_marginTop="3dp"
           android:background="@drawable/bg_button_with_corner_orange"
           android:gravity="center_vertical"
           android:padding="3dp">
   
           <TextView
               android:id="@+id/tvText"
               android:layout_width="wrap_content"
               android:layout_height="wrap_content"
               android:editable="false"
               android:singleLine="true"
               android:text="@string/app_name" />
   
           <ImageView
               android:id="@+id/ivDelete"
               android:layout_width="wrap_content"
               android:layout_height="match_parent"
               android:src="@android:drawable/ic_delete" />
   
       </LinearLayout>
   
       <AutoCompleteTextView
           android:id="@+id/tvAutocomplete"
           android:layout_width="200dp"
           android:layout_height="match_parent"
           android:imeOptions="actionDone"
           android:layout_marginLeft="5dp"
           android:background="@android:color/transparent"
           android:hint="@string/app_name"
           android:singleLine="true"
           android:textSize="12sp" />
   
   </LinearLayout>
   
   
   
   

    
9. Create a xml tag_layout.Java and update it-
   
   
   
   
   

   <?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="wrap_content">
   
       <android.support.v7.widget.RecyclerView
           android:id="@+id/rvTagList"
           android:layout_width="match_parent"
           android:layout_height="wrap_content" />
   </LinearLayout>
   
   
   
   

    
   
   
   

   
   
10. All the application development process with Base Activity has completed, Now run the app and look the screen. 
    
    

    

    
    
    
    
    
    
    

    

    

    
    

    
    
    

    
    

    
    

    
    

    
    
11. Good bye, Thanks to read this blog.
    
    

    
    

    
    

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