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How to get the id of a specific list item in android?

I use Listview and set multiple items, and each item has a "Like, share and comment" option. Actually I got the item id, as well as setText TextView , its successful. But it was not possible to get the item ID on the Like Like Click button for a specific item. How to get item id for all items in Listview on Button Click Event?

Demo for the MyAdapter class:

 public class Adapter1 extends BaseAdapter implements OnClickListener { public ArrayList<HashMap<String, String>> arr = null; Context context = null; LayoutInflater layoutInflater = null; HashMap<String, String> getData = new HashMap<String, String>(); String urlLike = null; TextView strId = null; public NewsFeedAdapter(Context context, ArrayList<HashMap<String, String>> arr) { this.context = context; this.arr= arr; layoutInflater = LayoutInflater.from(context); } @Override public int getCount() { return arr.size(); } @Override public Object getItem(int position) { return arr.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder = null; if (convertView == null) { convertView = layoutInflater.inflate( R.layout.my_list_item, null); /** initialize ViewHolder */ viewHolder = new ViewHolder(); /** Initialize Widgets */ /** Imageview */ viewHolder.imgLike = (ImageView) convertView .findViewById(R.id.imgLike); viewHolder.imgLike.setOnClickListener(this); viewHolder.imgComments = (ImageView) convertView .findViewById(R.id.imgComments); viewHolder.imgComments.setOnClickListener(this); viewHolder.imgShare = (ImageView) convertView .findViewById(R.id.imgShare); viewHolder.imgShare.setOnClickListener(this); /** TextView */ viewHolder.txtId = (TextView) convertView .findViewById(R.id.txtId); viewHolder.txtDescription = (TextView) convertView .findViewById(R.id.txtDescription); getData = arr.get(position); viewHolder.txtId.setText(getData .get(Fragment1.TAG_ID)); viewHolder.txtDescription.setText(getData .get(Fragment1.TAG_MESSAGE)); convertView.setTag(viewHolder); } else { viewHolder = (ViewHolder) convertView.getTag(); } convertView.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { } }); return convertView; } /** ViewHolder Class */ public class ViewHolder { ImageView imgLike = null, imgComments = null, imgShare = null; TextView txtId = null,txtDescription = null; } @Override public void onClick(View view) { switch (view.getId()) { case R.id.imgLike: strId = ((TextView) view .findViewById(R.id.txtId)); System.out.println("On Click=====" + strId.getText().toString()); urlLike = "http://www.example.com?id=" + strId.getText().toString() + "&user_id=" + myDetail.getUserId(); new sendLikeData().execute(); break; case R.id.imgComments: break; case R.id.imgShare: break; default: break; } } public class sendLikeData extends AsyncTask<Void, Void, Void> { protected void onPreExecute() { super.onPreExecute(); } @Override protected Void doInBackground(Void... arg0) { ServiceHandler sh = new ServiceHandler(); String jsonStr = sh.makeServiceCall(urlLike, ServiceHandler.GET); Log.d("Response : Like", ">" + jsonStr); return null; } protected void onPostExecute(Void result) { super.onPostExecute(result); }; } } OutPut is, NullPointer Exception in System.out.println("On Click=====" + strId.getText().toString());.

enter image description here

xml file

 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/masterLayout" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_margin="@dimen/five_dp" > <TextView android:id="@+id/txtDescription" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_marginLeft="@dimen/ten_dp" android:layout_marginRight="@dimen/ten_dp" android:layout_marginTop="@dimen/ten_dp" /> <ImageView android:id="@+id/imgImage" android:layout_width="fill_parent" android:layout_height="150dp" android:layout_below="@+id/txtDescription" android:layout_centerHorizontal="true" android:layout_marginBottom="@dimen/ten_dp" android:layout_marginLeft="@dimen/ten_dp" android:layout_marginRight="@dimen/ten_dp" android:layout_marginTop="@dimen/ten_dp" android:background="@null" android:contentDescription="@string/content_description" android:src="@drawable/ic_launcher" /> <LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/imgImage" android:background="@drawable/strip" android:baselineAligned="false" android:gravity="center_vertical" android:orientation="horizontal" > <RelativeLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="1" > <ImageView android:id="@+id/imgLike" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerInParent="true" android:contentDescription="@string/content_description" android:src="@drawable/like" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignTop="@+id/imgLike" android:layout_toRightOf="@+id/imgLike" android:background="@drawable/getbg" android:gravity="center" android:padding="@dimen/two_dp" android:textColor="@color/white" android:textSize="@dimen/ten_sp" /> </RelativeLayout> <RelativeLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="1" > <ImageView android:id="@+id/imgComments" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerInParent="true" android:contentDescription="@string/content_description" android:src="@drawable/comments" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_toRightOf="@+id/imgComments" android:background="@drawable/getbg" android:gravity="center" android:padding="@dimen/two_dp" android:text="+1" android:textColor="@android:color/white" android:textSize="@dimen/ten_sp" /> </RelativeLayout> <RelativeLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="1" > <ImageView android:id="@+id/imgShare" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerInParent="true" android:contentDescription="@string/content_description" android:src="@drawable/share" /> </RelativeLayout> </LinearLayout> <TextView android:id="@+id/txtId" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:layout_margin="@dimen/ten_dp" android:text="id" android:textSize="20dp" /> </RelativeLayout>

And there is Logcat,

 11-24 18:54:20.354: E/AndroidRuntime(7120): java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to android.widget.TextView 11-24 18:54:20.354: E/AndroidRuntime(7120): Adapter.onClick(Fragment.java:342) 11-24 18:54:20.354: E/AndroidRuntime(7120): at android.view.View.performClick(View.java:4562) 11-24 18:54:20.354: E/AndroidRuntime(7120): at android.view.View$PerformClick.run(View.java:18918) 11-24 18:54:20.354: E/AndroidRuntime(7120): at android.os.Handler.handleCallback(Handler.java:808) 11-24 18:54:20.354: E/AndroidRuntime(7120): at android.os.Handler.dispatchMessage(Handler.java:103) 11-24 18:54:20.354: E/AndroidRuntime(7120): at android.os.Looper.loop(Looper.java:193) 11-24 18:54:20.354: E/AndroidRuntime(7120): at android.app.ActivityThread.main(ActivityThread.java:5388) 11-24 18:54:20.354: E/AndroidRuntime(7120): at java.lang.reflect.Method.invokeNative(Native Method) 11-24 18:54:20.354: E/AndroidRuntime(7120): at java.lang.reflect.Method.invoke(Method.java:515) 11-24 18:54:20.354: E/AndroidRuntime(7120): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 11-24 18:54:20.354: E/AndroidRuntime(7120): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:655) 11-24 18:54:20.354: E/AndroidRuntime(7120): at dalvik.system.NativeStart.main(Native Method)
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6 answers

Try using the code below:

 public class Adapter1 extends BaseAdapter implements OnClickListener { public ArrayList<HashMap<String, String>> arr = null; Context context = null; LayoutInflater layoutInflater = null; HashMap<String, String> getData = new HashMap<String, String>(); String urlLike = null; TextView strId = null; public NewsFeedAdapter(Context context, ArrayList<HashMap<String, String>> arr) { this.context = context; this.arr= arr; layoutInflater = LayoutInflater.from(context); } @Override public int getCount() { return arr.size(); } @Override public Object getItem(int position) { return arr.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder = null; if (convertView == null) { convertView = layoutInflater.inflate( R.layout.my_list_item, null); /** initialize ViewHolder */ viewHolder = new ViewHolder(); /** Initialize Widgets */ /** Imageview */ viewHolder.imgLike = (ImageView) convertView .findViewById(R.id.imgLike); viewHolder.imgComments = (ImageView) convertView .findViewById(R.id.imgComments); viewHolder.imgComments.setOnClickListener(this); viewHolder.imgShare = (ImageView) convertView .findViewById(R.id.imgShare); viewHolder.imgShare.setOnClickListener(this); /** TextView */ viewHolder.txtId = (TextView) convertView .findViewById(R.id.txtId); viewHolder.txtDescription = (TextView) convertView .findViewById(R.id.txtDescription); getData = arr.get(position); viewHolder.txtId.setText(getData .get(Fragment1.TAG_ID)); viewHolder.txtDescription.setText(getData .get(Fragment1.TAG_MESSAGE)); convertView.setTag(viewHolder); } else { viewHolder = (ViewHolder) convertView.getTag(); } convertView.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { } }); viewHolder.imgLike.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { strId=arr.get(position).getId();//or whatever you want to do do here. } }); return convertView; } /** ViewHolder Class */ public class ViewHolder { ImageView imgLike = null, imgComments = null, imgShare = null; TextView txtId = null,txtDescription = null; } }
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You need to initialize strId in getView ()

here, in the following code, it cannot be initialized based on the "view" object, so you get nullpointer.

 case R.id.imgLike: strId = ((TextView) view.findViewById(R.id.txtId));

mark as allowed if you find the answer helpful.

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Try the following:

 strId = (TextView) view.getParent().findViewById(R.id.txtId);

This will fix your failure, but you need to think about your design.

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What you need to do is install Diff onclick Listeners in diff views

 viewHolder.txtDescription.setTag(R.id.txtDescription,position); viewHolder.txtDescription.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { int position_clicked=(Integer)v.getTag(); } });

repeat it for each view you want to set by the listener

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try it,

 @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder = null; if (convertView == null) { convertView = layoutInflater.inflate( R.layout.my_list_item, null); /** initialize ViewHolder */ viewHolder = new ViewHolder(); /** Initialize Widgets */ /** Imageview */ viewHolder.imgLike = (ImageView) convertView .findViewById(R.id.imgLike); viewHolder.imgLike.setOnClickListener(this); viewHolder.imgLike.setTag(position); viewHolder.imgComments = (ImageView) convertView .findViewById(R.id.imgComments); viewHolder.imgComments.setOnClickListener(this); viewHolder.imgShare = (ImageView) convertView .findViewById(R.id.imgShare); viewHolder.imgShare.setOnClickListener(this); /** TextView */ viewHolder.txtId = (TextView) convertView .findViewById(R.id.txtId); viewHolder.txtDescription = (TextView) convertView .findViewById(R.id.txtDescription); getData = arr.get(position); viewHolder.txtId.setText(getData .get(Fragment1.TAG_ID)); viewHolder.txtDescription.setText(getData .get(Fragment1.TAG_MESSAGE)); convertView.setTag(viewHolder); } else { viewHolder = (ViewHolder) convertView.getTag(); } convertView.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { } }); return convertView; } @Override public void onClick(View view) { switch (view.getId()) { case R.id.imgLike: View view = listview.getAdapter().getView(((ImageView)v).getTag(), null, listview); txtId = (TextView) view.findViewById(R.id.txtId); System.out.println("On Click=====" + strId.getText().toString()); urlLike = "http://www.example.com?id=" + strId.getText().toString() + "&user_id=" + myDetail.getUserId(); new sendLikeData().execute(); break; case R.id.imgComments: break; case R.id.imgShare: break; default: break; } }
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You can also use onClickListener inside your adapter class.

Check out this sample code.

 viewHolder.imgLike = (ImageView) convertView.findViewById(R.id.imgLike); viewHolder.imgLike.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub String id = getData.get(Fragment1.TAG_ID); } });
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Source: https://habr.com/ru/post/1207577/

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