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2 | 2 | // https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html |
3 | 3 |
|
4 | 4 | classPeekingIteratorimplementsIterator<Integer> { |
5 | | -IntegernextElement; |
6 | | -Iterator<Integer>iterator; |
| 5 | +privateIterator<Integer>iterator; |
| 6 | +privateIntegertopElement; |
| 7 | + |
7 | 8 | publicPeekingIterator(Iterator<Integer>iterator) { |
8 | 9 | // initialize any member here. |
9 | 10 | this.iterator =iterator; |
10 | | -updateNext(); |
11 | | - } |
12 | | - |
13 | | -privatevoidupdateNext() { |
14 | | -nextElement =iterator.hasNext() ?iterator.next() :null; |
| 11 | +populateTopElement(); |
15 | 12 | } |
16 | | -
|
| 13 | + |
17 | 14 | // Returns the next element in the iteration without advancing the iterator. |
18 | 15 | publicIntegerpeek() { |
19 | | -returnnextElement; |
| 16 | +returnthis.topElement; |
| 17 | + } |
| 18 | + |
| 19 | +// hasNext() and next() should behave the same as in the Iterator interface. |
| 20 | +// Override them if needed. |
| 21 | +@Override |
| 22 | +publicIntegernext() { |
| 23 | +IntegernextValue =this.topElement; |
| 24 | +populateTopElement(); |
| 25 | +returnnextValue; |
| 26 | + } |
| 27 | + |
| 28 | +@Override |
| 29 | +publicbooleanhasNext() { |
| 30 | +returnthis.topElement !=null; |
| 31 | + } |
| 32 | + |
| 33 | +privatevoidpopulateTopElement() { |
| 34 | +this.topElement =this.iterator.hasNext() ?this.iterator.next() :null; |
20 | 35 | } |
21 | | - |
22 | | -// hasNext() and next() should behave the same as in the Iterator interface. |
23 | | -// Override them if needed. |
24 | | -@Override |
25 | | -publicIntegernext() { |
26 | | -IntegerreturnValue =nextElement; |
27 | | -updateNext(); |
28 | | -returnreturnValue; |
29 | | -} |
30 | | - |
31 | | -@Override |
32 | | -publicbooleanhasNext() { |
33 | | -returnnextElement !=null; |
34 | | -} |
35 | 36 | } |