59

I am implementing Expandable List view in android and i am getting the above titled error. Please help me.

Main activity is - 

package com.expand;

import android.app.Activity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.Toast;


public class MyExpandableListViewActivity extends Activity {
    /** Called when the activity is first created. */



    static final String groupElements[]= {
           "India",
           "Australia",
           "England",
           "South Africa"
         };

    static final String[][] childElements=
    {
           {
          "Sachin Tendulkar",
          "Raina",
          "Dhoni",
          "Yuvi"
           },
           {
          "Ponting",
          "Adam Gilchrist",
          "Michael Clarke"
           },
           {
          "Andrew Strauss",
          "kevin Peterson",
          "Nasser Hussain"
           },
           {
          "Graeme Smith",
          "AB de villiers",
          "Jacques Kallis"
           }
            };



    DisplayMetrics metrics;
    int width;
    ExpandableListView expandList;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        expandList = (ExpandableListView)findViewById(R.id.expandList1);
        metrics = new DisplayMetrics();

        getWindowManager().getDefaultDisplay().getMetrics(metrics);
        width = metrics.widthPixels;

        //ExpAdapter adapter = new ExpAdapter(MyExpandableListViewActivity.this, groupElements, childElements);

        expandList.setAdapter(new ExpAdapter(MyExpandableListViewActivity.this, groupElements, childElements));
        expandList.setIndicatorBounds(width - GetDipsFromPixel(50), width - GetDipsFromPixel(10));


        expandList.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            @Override
            public void onGroupExpand(int groupPosition) {
                // TODO Auto-generated method stub

                 Log.e("onGroupExpand", "OK");
            }
        });

        expandList.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {

            @Override
            public void onGroupCollapse(int groupPosition) {
                // TODO Auto-generated method stub

                Log.e("onGroupCollapse", "OK");

            }
        });

        expandList.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {



            @Override
            public boolean onChildClick(ExpandableListView parent, View v,
                    int groupPosition, int childPosition, long id) {

                //getting the item that is selected
                //String s = (String) expandList.getItemAtPosition((int) id);

                Toast.makeText(MyExpandableListViewActivity.this, "You have selected :"  , Toast.LENGTH_SHORT).show();

                return false;
            }
        });

    }



    public int GetDipsFromPixel(float pixels)
    {
        // Get the screen's density scale
        final float scale = getResources().getDisplayMetrics().density;
        // Convert the dps to pixels, based on density scale
        return (int) (pixels * scale + 0.5f);
    }


}

ExpAdapter class is - I have implemented the adapter in other class and have called it in mt main activity

package com.expand;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;



    public class ExpAdapter extends BaseExpandableListAdapter {

        public Context myContext;
        public String[][] childElements;
        TextView childValues;
        public String[] groupElements;


        public ExpAdapter(Context context, String[] group, String[][] childs)
        {

            this.myContext=context;
            this.groupElements = group;
            this.childElements = childs;

        }



        @Override
        public Object getChild(int groupPosition, int childPosition) {
            // TODO Auto-generated method stub
            return childElements[groupPosition][childPosition];
        }

        @Override
        public long getChildId(int groupPosition, int childPosition) {
            // TODO Auto-generated method stub

            return 0;
        }

        @Override
        public View getChildView(int groupPosition, int childPosition,
                boolean isLastChild, View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub

            if(convertView==null){

                LayoutInflater inflator = (LayoutInflater)myContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView  = inflator.inflate(R.layout.child_rows, parent);

            }
            childValues = (TextView)convertView.findViewById(R.id.rowValues);
            childValues.setText(childElements[groupPosition][childPosition]);

            return convertView;
        }

        @Override
        public int getChildrenCount(int groupPosition) {
            // TODO Auto-generated method stub
            return groupElements[groupPosition].length();
        }

        @Override
        public Object getGroup(int groupPosition) {
            // TODO Auto-generated method stub
            return groupElements[groupPosition];
        }

        @Override
        public int getGroupCount() {
            // TODO Auto-generated method stub
            return groupElements.length;
        }

        @Override
        public long getGroupId(int groupPosition) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public View getGroupView(int groupPosition, boolean isExpanded,
                View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub

            if(convertView==null){
                LayoutInflater inflator = (LayoutInflater)myContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = inflator.inflate(R.layout.group_rows, null);
            }
            TextView group = (TextView)convertView.findViewById(R.id.groupId);
            group.setText(groupElements[groupPosition]);

            return convertView;
        }

        @Override
        public boolean hasStableIds() {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public boolean isChildSelectable(int groupPosition, int childPosition) {
            // TODO Auto-generated method stub
            return true;
        }




    }

main.xml-

this is the xnl that is displayed at the first by the main activity

  <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" >



        <ExpandableListView 
            android:id="@+id/expandList1"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            >


                 <TextView 
                android:id="@+id/android:empty"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                >
            </TextView>


        </ExpandableListView>


    </LinearLayout>

group_row.xml

this is the xml for the group elements

 <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/gropu_name"
        android:layout_width="fill_parent"
        android:layout_height="40dp"
        android:orientation="vertical" >


        <TextView 
            android:id="@+id/groupId"
            android:layout_height="40dp"
            android:layout_width="wrap_content"
            android:paddingLeft="30dp"
            android:gravity="center_vertical"
            android:textSize="16dp"
            android:textStyle="bold"
            />

    </LinearLayout>

child_row.xml this is the xml for the child elements

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="40dp"
    android:orientation="horizontal" >

    <TextView
        android:id="@+id/rowValues"
        android:layout_width="wrap_content"
        android:layout_height="30dp"
        android:gravity="center_vertical"
        android:paddingLeft="50dp"
        android:textSize="12dp" />


</LinearLayout>
Akram
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Gaurav Arora
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  • Error is appearing because **`you have added empty view at wrong place`**. You should **`not`** put `empty view` in between the starting and closing tags of `ExpandableListView`. Put it after closing tag of `ExpandableListView`. – Mehul Joisar Feb 16 '15 at 13:47

5 Answers5

128

Seems like Adapterview does not allow adding new view, I encountered same problem

Solve it by replacing following line

convertView  = inflator.inflate(R.layout.child_rows, parent);

to

convertView  = inflator.inflate(R.layout.child_rows, null);

UPDATE

Instead of not using a parent at all, you should simply tell the Inflater not to attach the inflated view to the parent with 

convertView = inflator.inflate(R.layout.child_rows, parent, false);

See also this answer.

The reason is that adapter takes care of attaching views to parent itself.

B-GangsteR
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Prashant Gami
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    Instead of not using a parent at all, you should simply tell the Inflater not to attach the inflated view to the parent with `convertView = inflator.inflate(R.layout.child_rows, parent, false);`. See also [this answer](http://stackoverflow.com/a/6419586/484293). – blubb May 28 '13 at 14:42
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    When is there a reason to set this to true? – user1007522 May 06 '14 at 11:14
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    Usually, the way inflator works is if you provide a parent reference, it will add that view to parent. In that case, return object you get will be parent object with child added to it not the child view object you added. Usually that is used when you just want to add views to viewgroup object like linearlayout. – Prashant Gami May 09 '14 at 00:40
11

Note that you can also get this error when your layout xml is invalid.

Justin
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2

As were noted above,

Instead of not using a parent at all, you should simply tell the Inflater not to attach the inflated view to the parent with 

 convertView = inflator.inflate(R.layout.child_rows, parent, false);

See also this answer.

The reason is that adapter takes care of attaching views to parent itself.

B-GangsteR
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0

According to Android Lint your child view should always provide a reference to its parent view when inflated. I had the exact same error in my code. Is was occurring because the TextView was placed inside the ExpandableListView. When I rearranged my xml layout the error stopped appearing.

sirFunkenstine
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0

This error can also be caused because of instant run feature. I was working on listview and because of this error app kept crashing. Uninstalling the app and running again resolved the error.

Illegal Argument
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