دوستان لطفآ کمک

 @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK)
        {
            return true; 
        }
        return super.onKeyDown(keyCode, event);
    }

این کد هستش...

 img_share.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                Intent shareIntent = new Intent(Intent.ACTION_SEND);
                shareIntent.setType("text/plain");
                shareIntent.putExtra(Intent.EXTRA_TEXT,
                        emdad.getOnvan() + "\n" + emdad.getNevisande() + "\n"
                                + emdad.getMatn() + "\n منبع: ");
                shareIntent.putExtra(Intent.EXTRA_SUBJECT, emdad.getOnvan());
                G.currentActivity.startActivity(Intent.createChooser(shareIntent, "اشتراک گذاری..."));
                // code marbut be share ro vasatun tu site mizaram
            }
        });
    }

این دو متد نوشته شدن... ادامه این خط کد ها

  @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        db.updateContact(emdad);
        db.close();// vaghti be activity ghabl bargasht dade shod db ro mibandim
                   // ta etelaat az byn nare
    }


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK)
        {
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
}