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Recycle view adapter in android

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Recycle view adapter
            The RecyclerView widget is a more advanced and flexible version of ListView. This widget is a container for displaying large data sets that can be scrolled very efficiently by maintaining a limited number of views. Use the RecyclerViewwidget when you have data collections whose elements change at runtime based on user action or network events.
The RecyclerView class simplifies the display and handling of large data sets by providing:
·         Layout managers for positioning items
·         Default animations for common item operations, such as removal or addition of items
You also have the flexibility to define custom layout managers and animations for RecyclerView widgets.


RecyclerViewFragment.class
public class RecyclerViewFragment extends Fragment {
    private static final String TAG = "RecyclerViewFragment";
    private static final String KEY_LAYOUT_MANAGER = "layoutManager";
    private static final int SPAN_COUNT = 2;
    private static final int DATASET_COUNT = 60;
    private enum LayoutManagerType {
        GRID_LAYOUT_MANAGER,
        LINEAR_LAYOUT_MANAGER
    }
    protected LayoutManagerType mCurrentLayoutManagerType;
    protected RadioButton mLinearLayoutRadioButton;
    protected RadioButton mGridLayoutRadioButton;
    protected RecyclerView mRecyclerView;
    protected CustomAdapter mAdapter;
    protected RecyclerView.LayoutManager mLayoutManager;
    protected String[] mDataset;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Initialize dataset, this data would usually come from a local content provider or
        // remote server.
        initDataset();
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.recycler_view_frag, container, false);
        rootView.setTag(TAG);
        // BEGIN_INCLUDE(initializeRecyclerView)
        mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
        // LinearLayoutManager is used here, this will layout the elements in a similar fashion
        // to the way ListView would layout elements. The RecyclerView.LayoutManager defines how
        // elements are laid out.
        mLayoutManager = new LinearLayoutManager(getActivity());
        mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;
        if (savedInstanceState != null) {
            // Restore saved layout manager type.
            mCurrentLayoutManagerType = (LayoutManagerType) savedInstanceState
                    .getSerializable(KEY_LAYOUT_MANAGER);
        }
        setRecyclerViewLayoutManager(mCurrentLayoutManagerType);
        mAdapter = new CustomAdapter(mDataset);
        // Set CustomAdapter as the adapter for RecyclerView.
        mRecyclerView.setAdapter(mAdapter);
        // END_INCLUDE(initializeRecyclerView)
        mLinearLayoutRadioButton = (RadioButton) rootView.findViewById(R.id.linear_layout_rb);
        mLinearLayoutRadioButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                setRecyclerViewLayoutManager(LayoutManagerType.LINEAR_LAYOUT_MANAGER);
            }
        });
        mGridLayoutRadioButton = (RadioButton) rootView.findViewById(R.id.grid_layout_rb);
        mGridLayoutRadioButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                setRecyclerViewLayoutManager(LayoutManagerType.GRID_LAYOUT_MANAGER);
            }
        });
        return rootView;
    }
    /**
     * Set RecyclerView's LayoutManager to the one given.
     *
     * @param layoutManagerType Type of layout manager to switch to.
     */
    public void setRecyclerViewLayoutManager(LayoutManagerType layoutManagerType) {
        int scrollPosition = 0;

        // If a layout manager has already been set, get current scroll position.
        if (mRecyclerView.getLayoutManager() != null) {
            scrollPosition = ((LinearLayoutManager) mRecyclerView.getLayoutManager())
                    .findFirstCompletelyVisibleItemPosition();
        }

        switch (layoutManagerType) {
            case GRID_LAYOUT_MANAGER:
                mLayoutManager = new GridLayoutManager(getActivity(), SPAN_COUNT);
                mCurrentLayoutManagerType = LayoutManagerType.GRID_LAYOUT_MANAGER;
                break;
            case LINEAR_LAYOUT_MANAGER:
                mLayoutManager = new LinearLayoutManager(getActivity());
                mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;
                break;
            default:
                mLayoutManager = new LinearLayoutManager(getActivity());
                mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER;
        }

        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.scrollToPosition(scrollPosition);
    }

    @Override
    public void onSaveInstanceState(Bundle savedInstanceState) {
        // Save currently selected layout manager.
        savedInstanceState.putSerializable(KEY_LAYOUT_MANAGER, mCurrentLayoutManagerType);
        super.onSaveInstanceState(savedInstanceState);
    }

    /**
     * Generates Strings for RecyclerView's adapter. This data would usually come
     * from a local content provider or remote server.
     */
    private void initDataset() {

        mDataset = new String[DATASET_COUNT];

        for (int i = 0; i < DATASET_COUNT; i++) {
            mDataset[i] = "This is element #" + i;
        }

    }
}

CustomAdapter.java
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
    private static final String TAG = "CustomAdapter";

    private String[] mDataSet;

    // BEGIN_INCLUDE(recyclerViewSampleViewHolder)
    /**
     * Provide a reference to the type of views that you are using (custom ViewHolder)
     */
    public static class ViewHolder extends RecyclerView.ViewHolder {
        private final TextView textView;

        public ViewHolder(View v) {
            super(v);
            // Define click listener for the ViewHolder's View.
            v.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Log.d(TAG, "Element " + getPosition() + " clicked.");
                }
            });
            textView = (TextView) v.findViewById(R.id.textView);
        }

        public TextView getTextView() {
            return textView;
        }
    }
    // END_INCLUDE(recyclerViewSampleViewHolder)

    /**
     * Initialize the dataset of the Adapter.
     *
     * @param dataSet String[] containing the data to populate views to be used by RecyclerView.
     */
    public CustomAdapter(String[] dataSet) {
        mDataSet = dataSet;
    }

    // BEGIN_INCLUDE(recyclerViewOnCreateViewHolder)
    // Create new views (invoked by the layout manager)
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        // Create a new view.
        View v = LayoutInflater.from(viewGroup.getContext())
                .inflate(R.layout.text_row_item, viewGroup, false);

        return new ViewHolder(v);
    }
    // END_INCLUDE(recyclerViewOnCreateViewHolder)

    // BEGIN_INCLUDE(recyclerViewOnBindViewHolder)
    // Replace the contents of a view (invoked by the layout manager)
    @Override
    public void onBindViewHolder(ViewHolder viewHolder, final int position) {
        Log.d(TAG, "Element " + position + " set.");

        // Get element from your dataset at this position and replace the contents of the view
        // with that element
        viewHolder.getTextView().setText(mDataSet[position]);
    }
    // END_INCLUDE(recyclerViewOnBindViewHolder)

    // Return the size of your dataset (invoked by the layout manager)
    @Override
    public int getItemCount() {
        return mDataSet.length;
    }
}

public class MainActivity extends SampleActivityBase {

    public static final String TAG = "MainActivity";

    // Whether the Log Fragment is currently shown
    private boolean mLogShown;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (savedInstanceState == null) {
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            RecyclerViewFragment fragment = new RecyclerViewFragment();
            transaction.replace(R.id.sample_content_fragment, fragment);
            transaction.commit();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        MenuItem logToggle = menu.findItem(R.id.menu_toggle_log);
        logToggle.setVisible(findViewById(R.id.sample_output) instanceof ViewAnimator);
        logToggle.setTitle(mLogShown ? R.string.sample_hide_log : R.string.sample_show_log);

        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch(item.getItemId()) {
            case R.id.menu_toggle_log:
                mLogShown = !mLogShown;
                ViewAnimator output = (ViewAnimator) findViewById(R.id.sample_output);
                if (mLogShown) {
                    output.setDisplayedChild(1);
                } else {
                    output.setDisplayedChild(0);
                }
                supportInvalidateOptionsMenu();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /** Create a chain of targets that will receive log data */
    @Override
    public void initializeLogging() {
        // Wraps Android's native log framework.
        LogWrapper logWrapper = new LogWrapper();
        // Using Log, front-end to the logging chain, emulates android.util.log method signatures.
        Log.setLogNode(logWrapper);
        // Filter strips out everything except the message text.
        MessageOnlyLogFilter msgFilter = new MessageOnlyLogFilter();
        logWrapper.setNext(msgFilter);
        // On screen logging via a fragment with a TextView.
        LogFragment logFragment = (LogFragment) getSupportFragmentManager()
                .findFragmentById(R.id.log_fragment);
        msgFilter.setNext(logFragment.getLogView());
        Log.i(TAG, "Ready");
    }
}

Activitymain.xml
<!--
  Copyright 2013 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->
<LinearLayout
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:id="@+id/sample_main_layout">

    <ViewAnimator
          android:id="@+id/sample_output"
          android:layout_width="match_parent"
          android:layout_height="0px"
          android:layout_weight="1">

        <ScrollView
              style="@style/Widget.SampleMessageTile"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

            <TextView
                  style="@style/Widget.SampleMessage"
                  android:layout_width="match_parent"
                  android:layout_height="wrap_content"
                  android:paddingLeft="@dimen/horizontal_page_margin"
                  android:paddingRight="@dimen/horizontal_page_margin"
                  android:paddingTop="@dimen/vertical_page_margin"
                  android:paddingBottom="@dimen/vertical_page_margin"
                  android:text="@string/intro_message" />
        </ScrollView>

        <fragment
              android:name="com.example.android.common.logger.LogFragment"
              android:id="@+id/log_fragment"
              android:layoout_width="match_parent"
              android:layout_height="match_parent" />

    </ViewAnimator>

    <View
          android:layout_width="match_parent"
          android:layout_height="1dp"
          android:backgrund="@android:color/darker_gray" />

    <FrameLayout
          android:id="@+id/sample_content_fragment"
          android:layout_weight="2"
          android:layout_width="match_parent"
          android:layout_height="0px" />

</LinearLayout>

Recycle_view_fragment.xml
<?xml version="1.0" encoding="UTF-8"?>
<!--
 Copyright 2014 The Android Open Source Project

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <RadioGroup
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:orientation="horizontal"
        android:checkedButton="@+id/linear_layout_rb">
        <RadioButton android:id="@+id/linear_layout_rb"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/linear_layout_manager"/>
        <RadioButton android:id="@+id/grid_layout_rb"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/grid_layout_manager"/>
    </RadioGroup>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

Text_row_item.xml
<?xml version="1.0" encoding="utf-8"?>
<!--
 Copyright 2014 The Android Open Source Project

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="@dimen/list_item_height"
    android:layout_marginLeft="@dimen/margin_medium"
    android:layout_marginRight="@dimen/margin_medium"
    android:gravity="center_vertical">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/element_text"/>
</FrameLayout>

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