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In the last lesson will you get it did it are specific to all kinds of collection objects.

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Non-Earth look at the list or Twitter which is specific to only less unindexed answer.

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It did it an interface on hands but with some additional functionality as well we'll see in this lesson

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if you recall we briefly mentioned about these new methods that list interface uploads.

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But we did not get into any details of this methods but these methods return an instance of Lister did

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it.

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Second one read and then listed the data starting from a particular index and the current list on what

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is the list the written interface it extends it to later on provides additional functionality.

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Little did it or we could only remove elements but using it later we can additionally add on Also replace

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elements.

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Moreover we can also iterate both forwards as well as backwards.

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That is it also supports bidirectional access.

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So we now have next our next.

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Just like in the case of regulator but in addition we also have Hosp. previous on previous previous

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would simply return the previous element.

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There are also the methods.

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Next and next and previous and next which give the index numbers of next on previous elements.

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Now here due to the bi directional axis remove motard would remove the element that was returned by

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the immediately preceding cone which has to be either next or previous.

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Otherwise an illegal state exception will be thrown in the case of a traitor.

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It was only the next invocation as there was no previous method any iterator.

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So the preceding call was an indication of next method then the element that was returned by that particular

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next invocation would be removed.

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But if the preceding call was an location of previous Medad then the element that was returned by that

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particular location or previous method would be more similar semantics would also apply for such a method

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.

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That is it updates the last element written by next our previous segment that would throw an illegal

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state exception if the immediate preceding call is not next or previous or better.

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So the immediately preceding call can be a segmented augmented simply adds an element an update updates

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the cursor position in the next slide.

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They will look at how the cursor works.

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So basically Mr. Twitter is a more Richard Ritter as it extends the reader interface and in terms of

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applications it may be useful for cross entries.

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Another application could be with installation software many times with such installation software.

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We go through multiple steps by clicking on the next button but then the software also provides back

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buttons where you can go back from the current screen in order to make any edits.

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So if a list or Twitter can be used with installation software in order to move forward it's as well

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as backwards.

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And here is something about the cursor position in this illustration.

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And elements from index 0 2 index and minus one.

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Now the red arrow indicates a up position so the cursor is in between two elements.

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It means that there is no concept of current element.

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Mr. Director that's the reason we have methods like next next next previous and next and previous.

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So there is no current index.

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So when we start that duration and we end up next index it would return zero.

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Similarly when we were previous indexed at the start of integration it would read an A minus one NAAFI

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next index when the cursor is at the end of the list.

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Then the size of the list would be returned.

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One thing to note here is let's say the cursor is in between.

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And this is zero on one NAAFI And what next method then element that in Expedition 1 would be written

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on the set would be in-between indices VH1 onto Nolfi in your previous method.

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Then once again the element that index position 1 would be written.

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So it's not going to return the element that index position zero.

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So to give the element index zero we need to invoke previous one more time.

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So that's a kind of behavior we get during the week Kosar works.

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Now let's head over to my eclipse to look at a shot them off list or did it or looking for wisdom or

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a new method card list.

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It did it for them or has been added to the list smokeless.

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So in just a month you're not going to write any new Coke in the interest of time.

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The matter has already been written so we're just going to look at the statements and we are going to

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execute this matter.

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So here we are creating another list and we are adding three elements.

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These are strengths.

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A B and C since it's an idealist all strings.

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So here we have a string here.

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So it's a list of strings and we are going to display the elements first.

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So here.

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So the element name and the Orderless name is list.

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So we're invoking the list.

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It didn't matter here under-treated and said list iterator off strings.

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OK and here we are using a furler in the previous DM or we used a y know what it did it in did it.

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But here in this case we are using the fuddle and we invoking the Hasek's method in order to do that

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.

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OK.

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So there is no increment operation so this expression is empty here and we are simply printing the next

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index as well as the next element.

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So let me run this as you can see it is printing the next numbers 0 1 2 and the corresponding elements

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.

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Now let's go ahead and run the rest of the code.

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Next we are actually demonstrative.

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I remove.

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I insert operations.

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So let's look at each of them separately.

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So let me just.

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OK so let me run it.

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So once again we are drifting through the list iterator.

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OK let's just the same for a for loop here.

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Let's look at the output.

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OK here we are.

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So here initially initially we are printing the next index.

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Here it is.

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So it is zero and we are also printing the element which is a.

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Then once we do that we are invoking the next and next one more time.

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OK.

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And that next index would be equal to 1.

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Right.

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Because the first time and it was in vogue because you don't know to be one on one it is what we want

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to do.

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A few operations here.

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One thing is we are printing the statement adding tested and next one here today.

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So we are going to add an element here.

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OK.

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So we are in the odd method on the iterator on the listed editor and it is adding this element called

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test.

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OK.

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Now this word I don't aliment under-covered Edwins the cursor.

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So when we invoke the next index here and the next statement it is actually ending the next two.

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So the element got.

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I did it in next one.

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It's just that the cursor got advanced and that's the reason when we invoke next index it is printing

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too.

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And here we are in working the next element.

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You did it or not.

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Next on that would actually return the element B which is which is now at position two.

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OK previous Newt was at position 1.

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So that's the odd operation.

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It's simply arch on advances the cursor position.

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Now let's look at the remote moment here.

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So we want to really muck best which was I did it in Expedition 1 but not the current position cursor

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position as B.

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Is it too.

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Sorry.

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Is it to iron when we invoke it did it or previous It would return that element B.

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Ok so here we are invoking the previous.

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But our goal is to remove the element test.

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So we need to invoke previous one more time here and when we do that then the element best would be

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returned.

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Now the goal is to remove the element test so we invoke the motard Rimmel.

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And so the previous since the previous call was lost previous which was returning the element test the

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remote work return that particular element.

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So we already discussed that the the preceding call would be more has to be either previous or it has

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to be next.

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Otherwise we get it we get an exception.

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So that's the remote amateur knowledge look at set operation for that operation here.

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Let me uncomment this sort of for the search operation.

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The preceding call has to be next or previous or set.

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So in this case the preceding cannulas the Rimmel.

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So in this case now if I run it it should give an illegal state exception as you can see it gives an

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legal state exception.

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So you cannot do that.

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So let me comment it out and then let me read on this.

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So now the element test has already been removed.

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So we are here on we are trending the next index.

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So the next and next will be one and the next element would be B.

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So now B is back at Expedition 1.

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Now we want to execute a set matter here and we want to set the element at index 1 as test.

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So we want to replace beb it best since here next has already been invoked in this system brought out

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statement.

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So we are free to use the set method.

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And so we are setting test now in the next statement.

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We want to set the aliment for them.

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We want to replace best met test the string test but just one.

153

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So we are setting one more time.

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So we are setting or just test one since set can be preceded by a set call.

155

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So it is perfectly fine on just would be replaced by Test 1.

156

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OK.

157

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So finally we are printing all the elements here.

158

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Once again we are using a fun loop.

159

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Now we now only have three elements in just one on seat.

160

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So that's the list iterator interface.

161

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And you can see that it supports previous next Raymo.

162

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And also segments.

163

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So it's a much more richer and richer.

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So that's about it.

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The code is available in the resource section.

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Thank you.

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Unhappy coding.