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POApplication throws null pointer exception when we try to capture selected checkbox ids on submit button in Android
 

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  1. POApplication throws null pointer exception when we try to capture selected checkbox ids on submit button in Android
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    <p>I have a grid layout with a EditText field on the top of the screen. I am implementing base adapter to fill in the value for grid layout. </p> <p>The code I am using is as follows. My main activity </p> <pre><code>public class MainActivityDynamic extends Activity{ GridView gridView; GridObject[] planets; ArrayList&lt;GridObject&gt; myObjects; Button Go; ImageAdapter adapter; int position; boolean[] itemChecked; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.gridlayout); Go = (Button)findViewById(R.id.bGO); gridView = (GridView) findViewById(R.id.gV); String[] primarycontext = {"first","second","third","fourth","fifth","sixth","seventh","eighth","ninth","tenth","leventh","twelth","thirteenth","fouteenth","fifteenth","sixteenth","seventeenth","eighteenth","nineteenth","twenteth","twentyfirst","twentysecond", "twentythird","twentythird","twentyfouth"}; gridView.setAdapter(new ImageAdapter(this, primarycontext)); gridView.setOnItemClickListener(new GridView.OnItemClickListener(){ public void onItemClick(AdapterView&lt;?&gt; arg0, View v, int position, long id) { // TODO Auto-generated method stub //myObjects.get(position).setState(1); //myAdapter.notifyDataSetChanged(); Toast.makeText(getBaseContext(), "clicked on "+position, Toast.LENGTH_SHORT).show(); } }); Go.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { // TODO Auto-generated method stub //adapter.notifyDataSetChanged(); int len = 10; int cnt = 0; String selectImages = ""; for (int i = 0;i&lt;len; i++){ if (adapter.itemChecked[i]){ cnt++; } } if(cnt == 0){ Toast.makeText(getBaseContext(), "please select atleast one", Toast.LENGTH_SHORT).show(); }else { Toast.makeText(getBaseContext(), "you have selected" + cnt + "boxes", Toast.LENGTH_SHORT).show(); } String item = (String) adapter.getItem(position); Toast.makeText(getBaseContext(), "selected fields"+item, Toast.LENGTH_SHORT).show(); } }); } } public class ImageAdapter extends BaseAdapter { Context mContext; public ImageAdapter(Context c,String[] primarycontext) { mContext = c; this.primarycontext = primarycontext; } @Override public int getCount() { // TODO Auto-generated method stub return providers.length; } public Object getItem(int position) { // TODO Auto-generated method stub return primarycontext[position]; } @Override public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub View v; if(convertView==null){ LayoutInflater li = (LayoutInflater) mContext .getSystemService(Context.LAYOUT_INFLATER_SERVICE); v = new View(mContext); v = li.inflate(R.layout.icon, null); } else { v = convertView; } ImageView iv = (ImageView)v.findViewById(R.id.grid_item_image); iv.setImageResource(R.drawable.folder_0); CheckBox CBx = (CheckBox)v.findViewById(R.id.cBIon); CBx.setText(primarycontext[position]); CBx.setChecked(isItemChecked(position)); return v; } private boolean isItemChecked(int position) { // TODO Auto-generated method stub System.out.println("the returning items="+itemChecked); return itemChecked; } } } </code></pre> <p>In the main layout I have a gridview occupied with a checkboxes with text and an Image. I have a Submit(Go) button which when clicked should capture all names of the checked boxes checked in main activity. How can I do that? When ever I run this code and click on Go, the application crashes and returns null pointer exception.</p> <p>Errors</p> <pre><code>11-25 05:43:50.390: E/AndroidRuntime(519): FATAL EXCEPTION: main 11-25 05:43:50.390: E/AndroidRuntime(519): java.lang.NullPointerException 11-25 05:43:50.390: E/AndroidRuntime(519): at com.example.kam1.MainActivityDynamic$2.onClick(MainActivityDynamic.java:73) 11-25 05:43:50.390: E/AndroidRuntime(519): at android.view.View.performClick(View.java:2408) 11-25 05:43:50.390: E/AndroidRuntime(519): at android.view.View$PerformClick.run(View.java:8816) 11-25 05:43:50.390: E/AndroidRuntime(519): at android.os.Handler.handleCallback(Handler.java:587) </code></pre>
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