java.lang.NullPointerException

Question

I developed a simple listview application which gets data from the MySQL database. It displayed listview but when I'm selecting a single listview it occurs following error.

this is my xml file for single list view,

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

<TextView android:id="@+id/product_label"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textSize="25dip"
        android:textStyle="bold"
        android:padding="10dip"
        android:textColor="#ffffff"/>   
</LinearLayout>

MainActivity.java file,

import java.util.List;

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.widget.Toast;
import android.content.Intent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;

import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends ListActivity implements FetchDataListener{
private ProgressDialog dialog;

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

    ListView lv = getListView();

    // listening to single list item on click
    lv.setOnItemClickListener(new OnItemClickListener() {
      public void onItemClick(AdapterView<?> parent, View view,
          int position, long id) {

          // selected item
          TextView txtview = ((TextView) view.findViewById(R.id.product_label));
          String product = txtview.getText().toString();

          // Launching new Activity on selecting single List Item
          Intent i = new Intent(getApplicationContext(), SingleListItem.class);
          // sending data to new activity
          i.putExtra("product", product);
          startActivity(i);

      }
    });

}

private void initView() {
    // show progress dialog
    dialog = ProgressDialog.show(this, "", "Loading...");

    String url = "http://pubbapp.comze.com/pubapp.php";
    FetchDataTask task = new FetchDataTask(this);
    task.execute(url);
}

@Override
public void onFetchComplete(List<Application> data) {
    // dismiss the progress dialog
    if(dialog != null)  dialog.dismiss();
    // create new adapter
    ApplicationAdapter adapter = new ApplicationAdapter(this, data);
    // set the adapter to list
    setListAdapter(adapter);        
}

@Override
public void onFetchFailure(String msg) {
    // dismiss the progress dialog
    if(dialog != null)  dialog.dismiss();
    // show failure message
    Toast.makeText(this, msg, Toast.LENGTH_LONG).show();        
}
}

this is the single list activity java file,

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

public class SingleListItem extends Activity{
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.setContentView(R.layout.single_list_item_view);

    TextView txtProduct = (TextView) findViewById(R.id.product_label);

    Intent i = getIntent();
    // getting attached intent data
    String product = i.getStringExtra("product");
    // displaying selected product name
    txtProduct.setText(product);

}
}

this is the error msg,

11-27 00:11:25.210: E/AndroidRuntime(9924): FATAL EXCEPTION: main
11-27 00:11:25.210: E/AndroidRuntime(9924): java.lang.NullPointerException
11-27 00:11:25.210: E/AndroidRuntime(9924):     at com.sj.jsondemo.MainActivity$1.onItemClick(MainActivity.java:35)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at android.widget.AdapterView.performItemClick(AdapterView.java:284)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at android.widget.ListView.performItemClick(ListView.java:3745)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:1980)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at android.os.Handler.handleCallback(Handler.java:587)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at android.os.Handler.dispatchMessage(Handler.java:92)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at android.os.Looper.loop(Looper.java:130)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at android.app.ActivityThread.main(ActivityThread.java:3691)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at java.lang.reflect.Method.invokeNative(Native Method)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at java.lang.reflect.Method.invoke(Method.java:507)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
11-27 00:11:25.210: E/AndroidRuntime(9924):     at dalvik.system.NativeStart.main(Native Method)
11-27 00:11:59.925: I/Process(9924): Sending signal. PID: 9924 SIG: 9

I tried to solve this problem, but I can't find any solution for this.please help me.

As @Manitoba said, getListView doesn't seem to exist. Btw, post your stack trace. — Joao Guilherme, Nov 26 '13 at 15:04
This Seems that each one is Unrelated to another. If you use ListActivity Where is your Listview in main.xml. If you use custom adapter, then where is your getview method? — Subramanian Ramsundaram, Nov 26 '13 at 15:05
`single_list_item_view` has a textview with id `product_label`. So post your adapter code and the xml that you inflate in getView — Raghunandan, Nov 26 '13 at 15:13
You are dereferencing a null pointer at `MainActivity.java` line 35. All this information is present in the stack trace. Duplicate. — user207421, Jun 18 '19 at 05:56

score 0 · Answer 1 · answered Nov 27 '13 at 01:54

0

Please support fully activity_main.xml
In you activity_main.xml which should contain ListView like below:

ListView android:id="@id/android:list"

answered Nov 27 '13 at 01:54

boiledwater

10,372
4
37
38

score 0 · Answer 2 · answered Nov 27 '13 at 02:30

0

It is because, when you click on the item, it pointing to a null value, there might be no value that can be fetched from database. Please keep a breakpoint at that null pointer location and see the value its retrieving.

answered Nov 27 '13 at 02:30

srikayala

446
6
21

in my listview there are ward num(int) and date time(string) but still occurs this error. – user2881604 Nov 27 '13 at 03:33
what are the values you are getting ?? not the data types check the values – srikayala Nov 27 '13 at 03:34
the values in my listview similar to this 1,2,.. and 2013-11-27 – user2881604 Nov 27 '13 at 04:04

java.lang.NullPointerException

2 Answers2