从Android应用程序打开Whatsapp联系人列表

我是 android新手并尝试执行以下任务： –
我想打开whatsapp联系人列表并获取选定的联系人数据.我能够完成一半的工作. whatsapp联系人列表打开,但一旦我按任何联系人我的应用程序崩溃.这是我的代码：

要打开whatsapp联系人列表：

btnChoose.setOnClickListener(new View.onClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(Intent.ACTION_PICK);
            intent.setPackage("com.whatsapp");
            try{
                Toast.makeText(AddscheduleActivity.this,"going out activity",Toast.LENGTH_SHORT).show();
                startActivityForResult(intent,1);
                Toast.makeText(AddscheduleActivity.this,"getTing In activity",Toast.LENGTH_SHORT).show();
            } catch (Exception E) {
                Toast.makeText(AddscheduleActivity.this,"whatsapp not found",Toast.LENGTH_SHORT).show();  //no activity found to handle this intent means whatsapp is not installed
            }
        }
    });

要获得选择： –

@Override
public void onActivityResult(int requestCode,int resultCode,Intent intent) {
    super.onActivityResult(requestCode,resultCode,intent);
    Toast.makeText(AddscheduleActivity.this,"Ok In",Toast.LENGTH_SHORT).show();

    switch (requestCodE) {
        case 1:
            if(resultCode == RESULT_OK){
                if(intent.hasExtra("contact")){

                    Toast.makeText(AddscheduleActivity.this,"Ok working",Toast.LENGTH_SHORT).show();
                    Uri uri = intent.getData();
                    //Query the content uri
                    cursor cursor = getContentResolver().query(uri,null,null);
                    cursor.moveToFirst();
                    // column index of the phone number
                    int  phoneIndex =cursor.getcolumnIndex(ContactsContract.CommonDataKinds.Phone.numbER);
                    // column index of the contact name
                    int  nameIndex =cursor.getcolumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_Name);
                    contactnumber = cursor.getString(phoneIndeX);
                    name = cursor.getString(nameIndeX);

                }
            }
            break;

        default:
            break;
    }
}

如果我没有选择任何联系并按回,那么在这种情况下他们不会崩溃

提前致谢.