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POOn Button Click how to increment counter and show in textview
 

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    <p>I am working on a shopping cart assignment for that I have created a custom ListView that contains the Picture, Price and Add to Cart button in each row. I also have a textview at the top which increments everytime the user presses the Add to cart. The Button in every row is perfectly working fine but I don't know how to increment the counter and set it to the textview as whenever I do this under onClick event I get runtime error. I am sharing with you the code. </p> <pre><code>package uet.cs08.bll; import java.util.ArrayList; import uet.cs08.android.R; import uet.cs08.android.mainActivity2; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.ImageView; import android.widget.TextView; public class itemBaseAdapter extends BaseAdapter { public int count = 5; private ArrayList&lt;ItemInfo&gt; itemList; private LayoutInflater mInflater; public itemBaseAdapter(Context context, ArrayList&lt;ItemInfo&gt; itemList){ this.itemList=itemList; mInflater= LayoutInflater.from(context); } @Override public int getCount() { return itemList.size(); } @Override public Object getItem(int idx) { return itemList.get(idx); } @Override public long getItemId(int idx) { // TODO Auto-generated method stub return idx; } @Override public View getView(int idx, View convertView, ViewGroup parent) { final ViewHolder holder; if(convertView==null){ convertView=mInflater.inflate(R.layout.item_list_row, null); holder = new ViewHolder(); holder.txtItemName=(TextView) convertView.findViewById(R.id.itemName); holder.txtPic=(ImageView) convertView.findViewById(R.id.pic); holder.txtPrice=(TextView) convertView.findViewById(R.id.price); holder.counter = (TextView) convertView.findViewById(R.id.tvCount); Button btn = (Button) convertView.findViewById(R.id.Cart); final TextView tv = (TextView)convertView.findViewById(R.id.tvCount); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { count = Integer.parseInt((String)tv.getText()); count++; tv.setText("" + count); } }); //tv.setText(""+count); convertView.setTag(holder); }else { holder = (ViewHolder) convertView.getTag(); } holder.txtItemName.setText(itemList.get(idx).itemName); holder.txtPic.setImageResource(itemList.get(idx).pic); holder.txtPrice.setText(""+itemList.get(idx).price); holder.counter.setText(itemList.get(idx).count); return convertView; } class ViewHolder { TextView txtItemName; ImageView txtPic; TextView txtPrice; TextView counter; } </code></pre> <p>} ` <strong>Here is the logCat.</strong> </p> <pre><code>03-20 16:16:38.853: D/AndroidRuntime(2759): Shutting down VM 03-20 16:16:38.853: W/dalvikvm(2759): threadid=1: thread exiting with uncaught exception (group=0x40015560) 03-20 16:16:38.883: E/AndroidRuntime(2759): FATAL EXCEPTION: main 03-20 16:16:38.883: E/AndroidRuntime(2759): java.lang.NullPointerException 03-20 16:16:38.883: E/AndroidRuntime(2759): at uet.cs08.bll.itemBaseAdapter$1.onClick(itemBaseAdapter.java:61) 03-20 16:16:38.883: E/AndroidRuntime(2759): at android.view.View.performClick(View.java:2485) 03-20 16:16:38.883: E/AndroidRuntime(2759): at android.view.View$PerformClick.run(View.java:9080) 03-20 16:16:38.883: E/AndroidRuntime(2759): at android.os.Handler.handleCallback(Handler.java:587) 03-20 16:16:38.883: E/AndroidRuntime(2759): at android.os.Handler.dispatchMessage(Handler.java:92) 03-20 16:16:38.883: E/AndroidRuntime(2759): at android.os.Looper.loop(Looper.java:123) 03-20 16:16:38.883: E/AndroidRuntime(2759): at android.app.ActivityThread.main(ActivityThread.java:3683) 03-20 16:16:38.883: E/AndroidRuntime(2759): at java.lang.reflect.Method.invokeNative(Native Method) 03-20 16:16:38.883: E/AndroidRuntime(2759): at java.lang.reflect.Method.invoke(Method.java:507) 03-20 16:16:38.883: E/AndroidRuntime(2759): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 03-20 16:16:38.883: E/AndroidRuntime(2759): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 03-20 16:16:38.883: E/AndroidRuntime(2759): at dalvik.system.NativeStart.main(Native Method) </code></pre>
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    1. COCheck if `tv` is null
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    2. COwhen you have error ,Always post full logcat here and dont forget in future
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    3. CODo you have single `TextView` to show counter at the top or in every row?
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      1. USAdil Soomro
 

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