Custom Expandable ListView - Android

Custom Expandable ListView – Android

Android has its own expandable listview ready-to-use but if you want to create your own expandable listview, follow this tutorial. All items will be read from a .txt file which contains a tree in form of Json.

Add .txt file to assets folder. If there is no assets folder in your project, you can add it by clicking File>New>Folder>Assets Folder.

The idea is that adding-removing lists to expand a list item. When you click on a list item:
*If item has at least one child and already expanded, then collapse it,
*If item has at least one child and collapsed, then expand it,
*Otherwise, do nothing.

Also, we have navigation buttons to move next item and previous item.

Let’s start with layout. We need a TextView to show current item label, a RecyclerView to list items and two buttons for navigation. Open activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<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:background="@color/colorLightGrey"
    tools:context="com.coffeebreakcodes.customexpandedlist.MainActivity">

    <TextView
        android:id="@+id/textViewLabel"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:background="@color/colorWhite"
        android:padding="16dp"
        android:textAlignment="center"
        android:textSize="18sp" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/layoutNavHolder"
        android:layout_below="@+id/textViewLabel"
        android:layout_marginBottom="2dp"
        android:scrollbars="vertical" />

    <RelativeLayout
        android:id="@+id/layoutNavHolder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="@color/colorGrey"
        android:padding="4dp">

        <ImageView
            android:id="@+id/imageViewLeft"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:src="@drawable/ic_keyboard_arrow_left_white_48dp" />

        <ImageView
            android:id="@+id/imageViewRight"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:src="@drawable/ic_keyboard_arrow_right_white_48dp" />

    </RelativeLayout>
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>

<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:background="@color/colorLightGrey"

tools:context="com.coffeebreakcodes.customexpandedlist.MainActivity">

<TextView

android:id="@+id/textViewLabel"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_alignParentTop="true"

android:background="@color/colorWhite"

android:padding="16dp"

android:textAlignment="center"

android:textSize="18sp" />

<android.support.v7.widget.RecyclerView

android:id="@+id/recyclerView"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:layout_above="@id/layoutNavHolder"

android:layout_below="@+id/textViewLabel"

android:layout_marginBottom="2dp"

android:scrollbars="vertical" />

<RelativeLayout

android:id="@+id/layoutNavHolder"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_alignParentBottom="true"

android:background="@color/colorGrey"

android:padding="4dp">

<ImageView

android:id="@+id/imageViewLeft"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentLeft="true"

android:src="@drawable/ic_keyboard_arrow_left_white_48dp" />

<ImageView

android:id="@+id/imageViewRight"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentRight="true"

android:src="@drawable/ic_keyboard_arrow_right_white_48dp" />

</RelativeLayout>

We also need a layout for list item which has a TextView for item label and an ImageView for “+,-” icons. Create an XML file named item_list.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layoutHolder"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorGrey"
    android:padding="4dp">

    <TextView
        android:id="@+id/textViewTitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="@color/colorWhite" />

    <ImageView
        android:id="@+id/imageViewIcon"
        android:layout_width="wrap_content"
        android:layout_height="16dp"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/layoutHolder"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:background="@color/colorGrey"

android:padding="4dp">

<TextView

android:id="@+id/textViewTitle"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:textColor="@color/colorWhite" />

<ImageView

android:id="@+id/imageViewIcon"

android:layout_width="wrap_content"

android:layout_height="16dp"

android:layout_alignParentEnd="true"

android:layout_alignParentRight="true" />

</RelativeLayout>

That’s all for layouts. You can define some colors. Before start coding, open app level gradle file and add these two libraries:

compile 'com.android.support:recyclerview-v7:26.+'
compile 'com.google.code.gson:gson:2.8.2'

1 2	compile 'com.android.support:recyclerview-v7:26.+' compile 'com.google.code.gson:gson:2.8.2'

We will use RecyclerView library for list and Gson library for parsing .txt file.

Item class contains id, title, child list, isExpanded, isSelected and hierarchy fields.

public class Item {
    private String identifier;
    private String title;
    private List<Item> item = new ArrayList<>();
    private boolean isExpanded = false;             //Is this item expanded?
    private boolean isSelected = false;             //Is selected item?
    private int hierarchy = 0;                      //Used for deciding indent by rank of item

    public String getIdentifier() {
        return identifier;
    }

    public void setIdentifier(String identifier) {
        this.identifier = identifier;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public List<Item> getItemList() {
        return item;
    }

    public void setItemList(List<Item> itemList) {
        this.item = itemList;
    }

    public boolean isExpanded() {
        return isExpanded;
    }

    public void setExpanded(boolean expanded) {
        isExpanded = expanded;
    }

    public int getHierarchy() {
        return hierarchy;
    }

    public void setHierarchy(int hierarchy) {
        this.hierarchy = hierarchy;
    }

    public boolean isSelected() {
        return isSelected;
    }

    public void setSelected(boolean selected) {
        isSelected = selected;
    }
}

public class Item {

private String identifier;

private String title;

private List<Item> item = new ArrayList<>();

private boolean isExpanded = false; //Is this item expanded?

private boolean isSelected = false; //Is selected item?

private int hierarchy = 0; //Used for deciding indent by rank of item

public String getIdentifier() {

return identifier;

}

public void setIdentifier(String identifier) {

this.identifier = identifier;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

public List<Item> getItemList() {

return item;

}

public void setItemList(List<Item> itemList) {

this.item = itemList;

}

public boolean isExpanded() {

return isExpanded;

}

public void setExpanded(boolean expanded) {

isExpanded = expanded;

}

public int getHierarchy() {

return hierarchy;

}

public void setHierarchy(int hierarchy) {

this.hierarchy = hierarchy;

}

public boolean isSelected() {

return isSelected;

}

public void setSelected(boolean selected) {

isSelected = selected;

}

Creating a constant class may help you to get constant variables easily. We will define navigation constants and indent values in this class.

public class Const {

    public static final int NAV_BASIC = 0;        //Click list item
    public static final int NAV_LEFT = 1;         //Left navigation button
    public static final int NAV_RIGHT = 2;        //Right navigation button

    public static final int MARGIN_START = 16;
    public static final int MARGIN_INDENT = 48;
}

public class Const {

public static final int NAV_BASIC = 0; //Click list item

public static final int NAV_LEFT = 1; //Left navigation button

public static final int NAV_RIGHT = 2; //Right navigation button

public static final int MARGIN_START = 16;

public static final int MARGIN_INDENT = 48;

}

Now, just think about what we need for listing all items. Create a java class named ItemRWAdapter. We will handle changing of icon and background color.

public class ItemRWAdapter extends RecyclerView.Adapter<ItemRWAdapter.ViewHolder> {

    private MainActivity activity;
    private List<Item> itemList;


    public ItemRWAdapter(MainActivity activity, List<Item> itemList) {
        this.activity = activity;
        this.itemList = itemList;
    }

    @Override
    public ItemRWAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_list, parent, false);
        return new ItemRWAdapter.ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ItemRWAdapter.ViewHolder holder, final int position) {
        Item item = itemList.get(position);
        holder.textViewTitle.setText(item.getTitle());

        //Places and changes images of items with children
        if (item.getItemList().size() > 0) {
            if (item.isExpanded()) {
                holder.imageViewIcon.setImageResource(R.drawable.ic_remove_white_48dp);
            } else {
                holder.imageViewIcon.setImageResource(R.drawable.ic_add_white_48dp);
            }
        } else {
            holder.imageViewIcon.setVisibility(View.GONE);
        }

        //Arranges the indent of rows in order to hierarchy
        RelativeLayout.LayoutParams params =
                (RelativeLayout.LayoutParams) holder.textViewTitle.getLayoutParams();
        params.setMargins(Const.MARGIN_START +
                (item.getHierarchy() * Const.MARGIN_INDENT), 0, 0, 0);
        holder.textViewTitle.setLayoutParams(params);

        //Changes background color of rows by selection
        if (item.isSelected()) {
            holder.layoutHolder.setBackgroundColor(
                    activity.getResources().getColor(R.color.colorRed));
        } else {
            holder.layoutHolder.setBackgroundColor(
                    activity.getResources().getColor(R.color.colorGrey));
        }

        holder.layoutHolder.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                activity.selectItem(position, Const.NAV_BASIC);
            }
        });
    }

    @Override
    public int getItemCount() {
        return itemList.size();
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView textViewTitle;
        ImageView imageViewIcon;
        RelativeLayout layoutHolder;

        public ViewHolder(View view) {
            super(view);
            textViewTitle = (TextView) view.findViewById(R.id.textViewTitle);
            imageViewIcon = (ImageView) view.findViewById(R.id.imageViewIcon);
            layoutHolder = (RelativeLayout) view.findViewById(R.id.layoutHolder);
        }
    }
}

public class ItemRWAdapter extends RecyclerView.Adapter<ItemRWAdapter.ViewHolder> {

private MainActivity activity;

private List<Item> itemList;

public ItemRWAdapter(MainActivity activity, List<Item> itemList) {

this.activity = activity;

this.itemList = itemList;

}

@Override

public ItemRWAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

View view = LayoutInflater.from(parent.getContext())

.inflate(R.layout.item_list, parent, false);

return new ItemRWAdapter.ViewHolder(view);

}

@Override

public void onBindViewHolder(final ItemRWAdapter.ViewHolder holder, final int position) {

Item item = itemList.get(position);

holder.textViewTitle.setText(item.getTitle());

//Places and changes images of items with children

if (item.getItemList().size() > 0) {

if (item.isExpanded()) {

holder.imageViewIcon.setImageResource(R.drawable.ic_remove_white_48dp);

} else {

holder.imageViewIcon.setImageResource(R.drawable.ic_add_white_48dp);

}

} else {

holder.imageViewIcon.setVisibility(View.GONE);

}

//Arranges the indent of rows in order to hierarchy

RelativeLayout.LayoutParams params =

(RelativeLayout.LayoutParams) holder.textViewTitle.getLayoutParams();

params.setMargins(Const.MARGIN_START +

(item.getHierarchy() * Const.MARGIN_INDENT), 0, 0, 0);

holder.textViewTitle.setLayoutParams(params);

//Changes background color of rows by selection

if (item.isSelected()) {

holder.layoutHolder.setBackgroundColor(

activity.getResources().getColor(R.color.colorRed));

} else {

holder.layoutHolder.setBackgroundColor(

activity.getResources().getColor(R.color.colorGrey));

}

holder.layoutHolder.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

activity.selectItem(position, Const.NAV_BASIC);

}

});

}

@Override

public int getItemCount() {

return itemList.size();

}

static class ViewHolder extends RecyclerView.ViewHolder {

TextView textViewTitle;

ImageView imageViewIcon;

RelativeLayout layoutHolder;

public ViewHolder(View view) {

super(view);

textViewTitle = (TextView) view.findViewById(R.id.textViewTitle);

imageViewIcon = (ImageView) view.findViewById(R.id.imageViewIcon);

layoutHolder = (RelativeLayout) view.findViewById(R.id.layoutHolder);

}

Now open MainActivity.java and write the code below.

public class MainActivity extends AppCompatActivity {

    private List<Item> itemList;
    private Item selectedItem;
    private int lastSelectedPosition = 0;

    private boolean isRecentlyClosed = false;       //Flag for collapsed list item

    private RecyclerView recyclerView;
    private TextView textViewLabel;
    private ImageView imageViewLeft;
    private ImageView imageViewRight;

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

        init();
    }

    private void init() {
        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        textViewLabel = (TextView) findViewById(R.id.textViewLabel);
        imageViewLeft = (ImageView) findViewById(R.id.imageViewLeft);
        imageViewRight = (ImageView) findViewById(R.id.imageViewRight);

        final Item item = getItemListFromAsset();
        if (item != null) {
            itemList = new ArrayList<>(item.getItemList());

            //Initial positioning
            selectedItem = itemList.get(0);
            itemList.get(0).setSelected(true);
            textViewLabel.setText(selectedItem.getTitle());
            imageViewLeft.setVisibility(View.GONE);

            recyclerView.setLayoutManager(new LinearLayoutManager(this));
            //Divider for RecyclerView
            recyclerView.addItemDecoration(new DividerItemDecoration(recyclerView.getContext(),
                    DividerItemDecoration.VERTICAL));
            recyclerView.setAdapter(new ItemRWAdapter(this, itemList));

            imageViewLeft.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if (lastSelectedPosition > 0) {
                        selectItem(lastSelectedPosition - 1, Const.NAV_LEFT);
                    }
                }
            });

            imageViewRight.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if (lastSelectedPosition < itemList.size() - 1) {
                        selectItem(lastSelectedPosition + 1, Const.NAV_RIGHT);
                    }
                }
            });
        } else {
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            final AlertDialog alertDialog = builder.create();
            alertDialog.setTitle("Error!");
            alertDialog.setMessage("Code: 1108");
            alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "Try Again", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    alertDialog.dismiss();
                    init();
                }
            });
            alertDialog.show();
        }
    }

    /**
     * Controls the selected item and updates the interface
     *
     * @param position position of selected item (int)
     * @param navType  type of navigation source (int)
     */
    public void selectItem(int position, int navType) {
        //Checks whether the current selected item has children to expand/collapse
        if (navType == Const.NAV_RIGHT && itemList.get(position - 1).getItemList().size() > 0 &&
                !itemList.get(position - 1).isExpanded()) {
            position = position - 1;
        } else if (navType == Const.NAV_LEFT && itemList.get(position + 1).getItemList().size() > 0 &&
                itemList.get(position + 1).isExpanded()) {
            position = position + 1;
        }

        //Visibility of navigation buttons on top of screen
        imageViewLeft.setVisibility(position == 0 ? View.GONE : View.VISIBLE);
        imageViewRight.setVisibility(position == itemList.size() - 1 ? View.GONE : View.VISIBLE);

        isRecentlyClosed = false;

        selectedItem = itemList.get(position);
        textViewLabel.setText(selectedItem.getTitle());
        itemList.get(position).setSelected(true);

        if (position != lastSelectedPosition) {
            itemList.get(lastSelectedPosition).setSelected(false);
        }
        lastSelectedPosition = position;

        //Delete children of collapsed list item from list
        if (selectedItem.getItemList().size() > 0) {
            if (selectedItem.isExpanded() && navType != Const.NAV_RIGHT) {
                deleteItemChildren(selectedItem, position);
            }
        }

        List<Item> updatedList = new ArrayList<>();

        //Add selected item and items till the selected item
        for (int i = 0; i < position + 1; i++) {
            updatedList.add(itemList.get(i));
        }

        //Add items if selected item has children
        if (selectedItem.getItemList().size() > 0 && !selectedItem.isExpanded() &&
                !isRecentlyClosed && navType != Const.NAV_LEFT) {
            updatedList.get(updatedList.size() - 1).setExpanded(true);
            for (int i = 0; i < selectedItem.getItemList().size(); i++) {
                Item item = selectedItem.getItemList().get(i);
                item.setExpanded(false);
                item.setHierarchy(selectedItem.getHierarchy() + 1);
                updatedList.add(item);
            }
        }

        //Add items coming after selected item
        for (int i = position + 1; i < itemList.size(); i++) {
            updatedList.add(itemList.get(i));
        }

        itemList = updatedList;
        recyclerView.setAdapter(new ItemRWAdapter(this, updatedList));
        if (navType != Const.NAV_BASIC) {
            recyclerView.getLayoutManager().scrollToPosition(position);
        }
    }

    /**
     * Gets JSON data from .txt file and converts to Item object
     *
     * @return
     */
    private Item getItemListFromAsset() {
        String json = "";
        JSONObject objTable = null;

        try {
            InputStream inputStream = getAssets().open("tree.txt");
            int size = inputStream.available();
            byte[] buffer = new byte[size];
            inputStream.read(buffer);
            inputStream.close();
            json = new String(buffer, "UTF-8");

        } catch (IOException ex) {
            ex.printStackTrace();
            Toast.makeText(
                    this, "File Error!", Toast.LENGTH_SHORT).show();
            return null;
        }

        try {
            JSONObject obj = new JSONObject(json);
            objTable = obj.getJSONObject("tableofcontents");

        } catch (JSONException e) {
            e.printStackTrace();
            Toast.makeText(
                    this, "FileError!", Toast.LENGTH_SHORT).show();
            return null;
        }

        return new Gson().fromJson(objTable.toString(), Item.class);
    }

    /**
     * Deletes all related children of selected parent recursively
     * in n-leveled parent-child list
     *
     * @param parentItem selected item
     * @param position   position of selected item
     */
    private void deleteItemChildren(Item parentItem, int position) {
        for (int i = 0; i < parentItem.getItemList().size(); i++) {
            Item innerItem = itemList.get(position + 1);
            itemList.remove(position + 1);

            if (innerItem.isExpanded() && innerItem.getItemList().size() > 0) {
                deleteItemChildren(innerItem, position);
            }
        }
        itemList.get(position).setExpanded(false);
        isRecentlyClosed = true;
    }
}

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public class MainActivity extends AppCompatActivity {

private List<Item> itemList;

private Item selectedItem;

private int lastSelectedPosition = 0;

private boolean isRecentlyClosed = false; //Flag for collapsed list item

private RecyclerView recyclerView;

private TextView textViewLabel;

private ImageView imageViewLeft;

private ImageView imageViewRight;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

init();

}

private void init() {

recyclerView = (RecyclerView) findViewById(R.id.recyclerView);

textViewLabel = (TextView) findViewById(R.id.textViewLabel);

imageViewLeft = (ImageView) findViewById(R.id.imageViewLeft);

imageViewRight = (ImageView) findViewById(R.id.imageViewRight);

final Item item = getItemListFromAsset();

if (item != null) {

itemList = new ArrayList<>(item.getItemList());

//Initial positioning

selectedItem = itemList.get(0);

itemList.get(0).setSelected(true);

textViewLabel.setText(selectedItem.getTitle());

imageViewLeft.setVisibility(View.GONE);

recyclerView.setLayoutManager(new LinearLayoutManager(this));

//Divider for RecyclerView

recyclerView.addItemDecoration(new DividerItemDecoration(recyclerView.getContext(),

DividerItemDecoration.VERTICAL));

recyclerView.setAdapter(new ItemRWAdapter(this, itemList));

imageViewLeft.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

if (lastSelectedPosition > 0) {

selectItem(lastSelectedPosition - 1, Const.NAV_LEFT);

}

});

imageViewRight.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

if (lastSelectedPosition < itemList.size() - 1) {

selectItem(lastSelectedPosition + 1, Const.NAV_RIGHT);

}

});

} else {

AlertDialog.Builder builder = new AlertDialog.Builder(this);

final AlertDialog alertDialog = builder.create();

alertDialog.setTitle("Error!");

alertDialog.setMessage("Code: 1108");

alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "Try Again", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialogInterface, int i) {

alertDialog.dismiss();

init();

}

});

alertDialog.show();

}

/**

* Controls the selected item and updates the interface

* @param position position of selected item (int)

* @param navType type of navigation source (int)

public void selectItem(int position, int navType) {

//Checks whether the current selected item has children to expand/collapse

if (navType == Const.NAV_RIGHT && itemList.get(position - 1).getItemList().size() > 0 &&

!itemList.get(position - 1).isExpanded()) {

position = position - 1;

} else if (navType == Const.NAV_LEFT && itemList.get(position + 1).getItemList().size() > 0 &&

itemList.get(position + 1).isExpanded()) {

position = position + 1;

}

//Visibility of navigation buttons on top of screen

imageViewLeft.setVisibility(position == 0 ? View.GONE : View.VISIBLE);

imageViewRight.setVisibility(position == itemList.size() - 1 ? View.GONE : View.VISIBLE);

isRecentlyClosed = false;

selectedItem = itemList.get(position);

textViewLabel.setText(selectedItem.getTitle());

itemList.get(position).setSelected(true);

if (position != lastSelectedPosition) {

itemList.get(lastSelectedPosition).setSelected(false);

}

lastSelectedPosition = position;

//Delete children of collapsed list item from list

if (selectedItem.getItemList().size() > 0) {

if (selectedItem.isExpanded() && navType != Const.NAV_RIGHT) {

deleteItemChildren(selectedItem, position);

}

List<Item> updatedList = new ArrayList<>();

//Add selected item and items till the selected item

for (int i = 0; i < position + 1; i++) {

updatedList.add(itemList.get(i));

}

//Add items if selected item has children

if (selectedItem.getItemList().size() > 0 && !selectedItem.isExpanded() &&

!isRecentlyClosed && navType != Const.NAV_LEFT) {

updatedList.get(updatedList.size() - 1).setExpanded(true);

for (int i = 0; i < selectedItem.getItemList().size(); i++) {

Item item = selectedItem.getItemList().get(i);

item.setExpanded(false);

item.setHierarchy(selectedItem.getHierarchy() + 1);

updatedList.add(item);

}

//Add items coming after selected item

for (int i = position + 1; i < itemList.size(); i++) {

updatedList.add(itemList.get(i));

}

itemList = updatedList;

recyclerView.setAdapter(new ItemRWAdapter(this, updatedList));

if (navType != Const.NAV_BASIC) {

recyclerView.getLayoutManager().scrollToPosition(position);

}

/**

* Gets JSON data from .txt file and converts to Item object

* @return

private Item getItemListFromAsset() {

String json = "";

JSONObject objTable = null;

try {

InputStream inputStream = getAssets().open("tree.txt");

int size = inputStream.available();

byte[] buffer = new byte[size];

inputStream.read(buffer);

inputStream.close();

json = new String(buffer, "UTF-8");

} catch (IOException ex) {

ex.printStackTrace();

Toast.makeText(

this, "File Error!", Toast.LENGTH_SHORT).show();

return null;

}

try {

JSONObject obj = new JSONObject(json);

objTable = obj.getJSONObject("tableofcontents");

} catch (JSONException e) {

e.printStackTrace();

Toast.makeText(

this, "FileError!", Toast.LENGTH_SHORT).show();

return null;

}

return new Gson().fromJson(objTable.toString(), Item.class);

}

/**

* Deletes all related children of selected parent recursively

* in n-leveled parent-child list

* @param parentItem selected item

* @param position position of selected item

private void deleteItemChildren(Item parentItem, int position) {

for (int i = 0; i < parentItem.getItemList().size(); i++) {

Item innerItem = itemList.get(position + 1);

itemList.remove(position + 1);

if (innerItem.isExpanded() && innerItem.getItemList().size() > 0) {

deleteItemChildren(innerItem, position);

}

itemList.get(position).setExpanded(false);

isRecentlyClosed = true;

}

You can find this project files on Github. Ask your questions as comment this page.

iOS – Android – KMM

iOS – Android – KMM

Custom Expandable ListView – Android