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CSE143 Sample Program handout #6
Sample client code: Class IntListSample2.java
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// Stuart Reges
// 4/4/05
//
// Demonstrates some basic use of an IntListIterator
public class IntListSample2 {
public static void main(String[] args) {
IntList list = new IntList(25);
for (int i = 0; i < 25; i++)
list.add((int)(5* Math.random()));
System.out.println(list);
IntListIterator i = list.iterator();
while (i.hasNext())
if (i.next() == 3)
i.remove();
System.out.println(list);
}
}
Sample Execution of IntListSample2
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[1, 0, 0, 3, 0, 3, 3, 3, 4, 2, 1, 2, 1, 1, 2, 2, 4, 4, 1, 0, 2, 1, 2, 3, 1]
[1, 0, 0, 0, 4, 2, 1, 2, 1, 1, 2, 2, 4, 4, 1, 0, 2, 1, 2, 1]
New Method added to IntList.java
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// post: returns an iterator for this list
public IntListIterator iterator() {
return new IntListIterator(this);
}
Class IntListIterator.java
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// Stuart Reges
// 4/4/05
//
// The IntListIterator class provides a set of utilities for iterating over
// an IntList and possibly removing values from the list.
import java.util.*;
public class IntListIterator {
private IntList list; // list to iterate over
private int position; // current position within the list
private boolean removeOK; // whether it's okay to remove now
// pre : list != null
// post: constructs an iterator for the given list
public IntListIterator(IntList list) {
this.list = list;
this.position = 0;
this.removeOK = false;
}
// post: returns true if there are more elements left, false otherwise
public boolean hasNext() {
return this.position < this.list.size();
}
// pre : hasNext()
// post: returns the next element in the iteration
public int next() {
if (!this.hasNext())
throw new NoSuchElementException();
int result = this.list.get(position);
this.position++;
this.removeOK = true;
return result;
}
// pre : next() has been called without a call on remove (i.e., at most one
// call on remove per call on next)
// post: removes the last element returned by the iterator
public void remove() {
if (!this.removeOK)
throw new IllegalStateException();
this.list.remove(this.position - 1);
this.position--;
this.removeOK = false;
}
}
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