Question

I want to sort and reverse sorting in single button click but i able to did only one, how can i implement this sorting and reverse sorting in consecutive button clicks.

 btn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            Comparator<Book> bb=Collections.reverseOrder();
                bk=Arrays.asList(books);
               Collections.sort(bk,bb);
                //Collections.shuffle(bk);
             // Collections.sort(bk);
                bookListView.invalidateViews();

        }
    });

Answer 1

Use a Boolean field whose initial value is true. In click handler of button, compare the boolean field value, if it is true then do sort and set false to boolean field. If boolean value is false then do reverse and set true to boolean field.

boolean state=true;

btn.setOnClickListener(new OnClickListener() {
   @Override
   public void onClick(View v) {
    if(state) {
        //sort
        state=false;
     }
   else{
      //reverse
      state=true;
     }
    }
 });