android setOnClickListener gives null pointer exception?

I have written code for onClick method for Custom Dialog top of the another view. It gives me nullpointer exception. I've also tried using Layout inflater. It gives me error on ok.setOnclickListener. What's wrong in my code?

 ImageButton search =(ImageButton) findViewById(R.id.search);
            search.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {

                    Dialog searchDialog = new Dialog(Page.this);

                    /*LayoutInflater inflater = (LayoutInflater) getApplicationContext()
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);


                     View layout = inflater.inflate(R.layout.search, null);
                     searchDialog.addContentView(layout, new LayoutParams(
                                LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
           开发者_JAVA技巧          searchDialog.setContentView(layout);*/

                    searchDialog.setContentView(R.layout.search);
                    searchDialog.setTitle("Search Dialog");
                    searchDialog.setCancelable(true);

                    Button ok = (Button)findViewById(R.id.OkButton);
                    ok.setOnClickListener(new OnClickListener() {

                        @Override
                        public void onClick(View v) {
                            String searchString = null;
                            EditText searchText = (EditText)findViewById(R.id.searchText);
                            if(searchText.getText()!=null){
                                searchString = searchText.getText().toString();
                            }
                            Log.i("TAG","Search word :"+searchString);

                        }
                    });

                    searchDialog.show();



                }


            });

You are looking for the button in the activity that creates the dialog instead of the dialog itself. The findViewById line should be:

Button ok = (Button)searchDialog.findViewById(R.id.OkButton);